tag:theconversation.com,2011:/fr/topics/selective-breeding-11089/articlesSelective breeding – The Conversation2021-11-02T19:07:04Ztag:theconversation.com,2011:article/1702712021-11-02T19:07:04Z2021-11-02T19:07:04ZCan selective breeding of ‘super kelp’ save our cold water reefs from hotter seas?<figure><img src="https://images.theconversation.com/files/429459/original/file-20211031-37789-svytub.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4288%2C2848&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Institute for Marine and Antarctic Studies</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Australia’s vital kelp forests are disappearing in many areas as our waters warm and our climate changes. </p>
<p>While we wait for rapid action to slash carbon emissions – including the United Nations climate talks now underway in Glasgow – we urgently need to buy time for these vital ecosystems. </p>
<p>How? By ‘future-proofing’ our kelp forests to be more resilient and adaptable to changing ocean conditions. Our recent trials have shown selectively bred kelp with higher heat tolerance can be successfully replanted and used in restoration.</p>
<p>This matters because these large seaweed species are the foundation of Australia’s <a href="https://theconversation.com/australias-other-reef-is-worth-more-than-10-billion-a-year-but-have-you-heard-of-it-45600">Great Southern Reef</a>, a vast but little-known <a href="https://www.abc.net.au/news/2020-05-19/great-southern-reef-needs-more-attention-scientists-say/12227998">temperate reef system</a> and a global hotspot of biodiversity.</p>
<p>The reef’s kelp forests run along 8000 km of Australia’s southern coastline, from Geraldton in Western Australia to the Queensland border with New South Wales. These underwater forests support coastal food-webs and fisheries. Think of the famous mass-spawning of Australian Giant Cuttlefish off Whyalla, the rock lobster and abalone fisheries, or our iconic weedy and leafy seadragons.</p>
<p>Unfortunately, these seas are hotspots in the literal sense, with the nation’s southeast and southwest waters <a href="https://link.springer.com/article/10.1007/s11160-013-9326-6">warming several times faster than the global average </a>and suffering from some of the <a href="https://theconversation.com/how-much-do-marine-heatwaves-cost-the-economic-losses-amount-to-billions-and-billions-of-dollars-170008">worst marine heatwaves recorded</a>. </p>
<p>These increasing temperatures and other climate change impacts are devastating our kelp, including shrinking forests and permanent losses of golden kelp (<em>Ecklonia radiata</em>) on the <a href="https://www.abc.net.au/news/2021-08-22/tropical-fish-sea-urchins/100396162">east</a> and <a href="https://theconversation.com/a-marine-heatwave-has-wiped-out-a-swathe-of-was-undersea-kelp-forest-62042">west coasts</a>, and <a href="https://www.imas.utas.edu.au/news/news-items/satellite-images-track-decline-of-tasmanias-giant-kelp-forests">staggering declines</a> of the now-endangered giant kelp (<em>Macrocystis pyrifera</em>) forests in Tasmania. </p>
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<a href="https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Golden kelp forest" src="https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429669/original/file-20211102-27-9dqafn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Golden kelp forests support a wealth of life.</span>
<span class="attribution"><span class="source">Andrew Green</span>, <span class="license">Author provided</span></span>
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Read more:
<a href="https://theconversation.com/australias-other-reef-is-worth-more-than-10-billion-a-year-but-have-you-heard-of-it-45600">Australia's 'other' reef is worth more than $10 billion a year - but have you heard of it?</a>
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<h2>We need novel measures to buy time for climate action</h2>
<p>Australian researchers are leading the way to try to find ways of future-proofing our critical ocean ecosystems, such as kelp forests and <a href="https://theconversation.com/meet-the-super-corals-that-can-handle-acid-heat-and-suffocation-122637">coral reefs</a>. In part, that’s because climate change is hitting our ecosystems early and hard. </p>
<p>Climate change is moving much faster than kelp species can adapt. In turn, that threatens all the species that rely on these forests, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3810891/">including us</a>.</p>
<p>If climate change wasn’t happening, we could try to halt or reverse the losses of kelp forests by using traditional restoration methods.
But in a world getting hotter and hotter, that is futile in many cases. Even if we slash carbon emissions soon, decades more warming are <a href="https://www.nytimes.com/2021/08/09/climate/climate-change-report-ipcc-un.html">already locked in</a>.</p>
<p>If we want to keep these forests of the sea alive, we must now consider cutting-edge methods to help kelp survive current and future ocean conditions while governments pursue the urgent goal of reducing emissions. </p>
<h2>How to future proof an underwater forest</h2>
<p>Together and separately, we’ve been exploring techniques to speed up the natural rate of evolution to boost kelp resilience. Along with other researchers, we’ve put several techniques to the test in the real world, with promising results. Others remain hypothetical. </p>
<p>At present, there are <a href="https://www.frontiersin.org/articles/10.3389/fmars.2020.00237/full">several broad approaches</a> to future-proofing restoration work. These include:</p>
<ul>
<li><p><strong>Genetic rescue</strong> focuses on enhancing the genetic diversity of genetically compromised populations to boost their potential to adapt to future conditions. This involves planting and restoring a mix of kelp from <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.13707">disconnected populations</a> of the same species. Improved genetic diversity can boost the ability of these forests to respond to change. We expect this approach to be especially useful in areas where climate change poses a limited threat at present. </p></li>
<li><p><strong>Assisted gene flow</strong> strategies introduce naturally adapted or tolerant kelp individuals into threatened populations to increase their ability to survive specific threats, like hotter seas. This could help kelp forests in areas affected by climate change now or in the near future. In these situations, the genetic rescue technique could be counterproductive if the new genetic diversity introduced isn’t able to cope with the heat. </p></li>
<li><p><strong>Selective breeding</strong> is a well-known agricultural technique, and can be used to identify the best kelp to use in these cases. In short, we try to identify kelp with naturally higher tolerance, and then use these as the basis for restoration efforts. These can be transplanted into ailing kelp forests. <a href="https://www.abc.net.au/news/2021-10-13/kelp-forests-off-tasmania-regrowing-a-year-since-project-began/100532756">Trials are presently underway</a> in Tasmania using giant kelp. Early results are exciting, with the largest ‘super kelp’ growing over 12 metres high a year after being planted.</p></li>
</ul>
<p>In the future, we may have to explore more cutting-edge strategies to deal with the changing conditions. These include:</p>
<ul>
<li><p><strong>Genetic manipulation.</strong> This technique extends what is possible with selective breeding by directly manipulating genes to enhance the traits or characteristics that might further boost kelp’s ability to thrive in hotter waters. </p></li>
<li><p><strong>Assisted expansion</strong> is when species with little chance of survival are relocated to better but novel locations, assuming these exist. This technique could also see new species of kelp being planted to replace existing species, guided by the need to protect the forest ecosystem as a whole, rather than save specific species. </p></li>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/underwater-health-check-shows-kelp-forests-are-declining-around-the-world-68569">Underwater health check shows kelp forests are declining around the world</a>
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<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist experimenting on kelp" src="https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429674/original/file-20211102-13-1o4uuod.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Co-author Adjunct Professor Melinda Coleman working on kelp genomics as part of her selective breeding research.</span>
<span class="attribution"><span class="source">Photo by Alejandro Tagliafico</span>, <span class="license">Author provided</span></span>
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<h2>Are these approaches ethical?</h2>
<p>Each of these techniques – tested or untested – pose challenging ethical questions. That’s because we are not undertaking traditional conservation, where we work to restore a historic kelp ecosystem. Instead, we are modifying these ecosystems in the hope they can better cope with conditions at the extremes of their current survival limits.</p>
<p>That means we must move carefully, weighing potential downsides like genetic pollution and maladaptation (accidental poor adaptation to other stressors) against the probability of further kelp forest destruction from doing nothing. </p>
<p>Such future-proofing interventions could be well suited to areas already hit hard by severe kelp forest losses, those that will be threatened in the near future, or where kelp losses would be particularly damaging environmentally, socially, or economically. </p>
<p>What is certain is that communities that live and rely on our southern coasts must now talk about what they value from kelp forests, and how they want them to look and function into the future. </p>
<p>Our view is that traditional approaches focused on recreating previous ecosystems are likely to be increasingly challenging, given the rate and scale of ongoing disruption in our oceans. </p>
<p>It is crucial that we do not restore nostalgically for ocean conditions which are quickly changing, but instead, work to ensure the long-term survival of these spectacular underwater forests while we wait for rapid action to reduce carbon emissions.</p><img src="https://counter.theconversation.com/content/170271/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cayne Layton receives funding from the University of Tasmania, The Nature Conservancy, and the Australian Government's National Environmental Science Program. </span></em></p><p class="fine-print"><em><span>Melinda Coleman receives funding from The Australian Research Council. She works for NSW Department of Primary Industries.
</span></em></p>Can we breed kelp and other keystone species to survive warming and marine heatwaves? These techniques have promise – but they’re not a silver bullet.Cayne Layton, Postdoctoral fellow and lecturer, University of TasmaniaMelinda Coleman, Adjunct Professor, Southern Cross University and Associate Professor, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1148002019-04-09T11:07:09Z2019-04-09T11:07:09ZMysterious museum shows how humans have modified nature for themselves – with important consequences<figure><img src="https://images.theconversation.com/files/268340/original/file-20190409-2898-njp1m4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1003%2C782&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Genetically modified mice express a green fluorescent protein which causes them to glow in the dark.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:GFP_Mice_01.jpg">Moen et al. (2012)/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Humans have shaped aspects of the living world to suit themselves throughout their history. We’ve domesticated plants and animals for food, security and companionship for tens of <a href="https://www.britannica.com/science/domestication">thousand of years</a>, ensuring <a href="https://www.nature.com/articles/nature01019">early civilisations could survive</a>, develop, and eventually <a href="https://www.nationalgeographic.org/encyclopedia/domestication/">trade</a> with each other.</p>
<p>Throughout history, our relationship with other species has been tied to meeting human needs. Species have been <a href="https://www.yourgenome.org/facts/what-is-selective-breeding">selectively bred</a> so that their offspring over-express particular genetic traits, such as obedient behaviour in dogs or larger size and power in horses. </p>
<p>Over time humans have become more ambitious about <a href="http://science.sciencemag.org/content/316/5833/1866">choosing behavioural and physical traits</a> to embed in other life forms. In recent decades, humans have also become increasingly capable of <a href="https://www.yourgenome.org/facts/what-is-genetic-engineering">genetically engineering</a> species – manipulating their DNA by splicing or inserting genetic material from other species into their genome.</p>
<p>A museum which opened in Pittsburgh, USA in 2012 has sought to chart the human influence in the biology of other species. The <a href="https://postnatural.org/">Center for PostNatural History</a> invites visitors to explore how humans have shaped the living world, <a href="https://postnatural.org/About">defining “postnatural history”</a> as: </p>
<blockquote>
<p>the study of the origins, habitats, and evolution of organisms that have been intentionally and heritably altered by humans.</p>
</blockquote>
<p>The Center’s director and founder, <a href="https://www.cmu.edu/cas/people/pell_richard.html">Richard Pell</a>, went further in <a href="https://theinfluencers.org/en/center-for-postnatural-history/video/1">explaining the postnatural</a>.</p>
<blockquote>
<p>It’s not just giving a dog a weird haircut, it’s breeding a dog that has weird hair. And its offspring will have weird hair forever. It’s sculpting the evolutionary process. […] It’s that moment at which culture intervenes in nature, and the organism has not just a story to tell about evolution or habitat, but has a story to tell about us.</p>
</blockquote>
<h2>The postnatural planet</h2>
<p>The Center claims to be the world’s only museum that is exclusively focused on postnatural lifeforms, exhibiting species often <a href="https://vimeo.com/56855772">omitted from typical natural history museums</a>. There’s a <a href="https://theinfluencers.org/en/center-for-postnatural-history/video/2">hairless, obese rat</a>, fish which <a href="https://postnatural.org/Press-1/Nature-Interview">glow in the dark</a>, and <a href="https://postnatural.org/Exhibits/Transgenic-Mosquito-of-Southern-California">transgenic mosquitoes</a> which have been bred so they can’t carry dengue fever. There’s also a mix of familiar species – different breeds of dogs and chickens – and species often less associated with human interference, such as <a href="http://science.sciencemag.org/content/143/3606/538">corn</a>, <a href="https://www.sciencedirect.com/science/article/pii/S2405985416300295">bananas</a> and <a href="https://books.google.co.uk/books?hl=en&lr=&id=G95hgSRYy9kC&oi=fnd&pg=PA1&dq=domestication+%2522chestnut+tree%2522&ots=pcIuLzmX3n&sig=midn-DHfvCaYdWdzVfHGQCE2tNA#v=onepage&q=domestication%2520%2522chestnut%2520tree%2522&f=false">chestnut trees</a>. </p>
<p>All these species, and many others, have different genetic traits over-expressed to accentuate desirable features. Dogs, for example, have been domesticated and selectively bred out from a common wolf ancestor to more than <a href="http://www.fci.be/en/Nomenclature/">350 breeds</a>, according to strict guidelines in keeping with particular cultural desires around behavioural traits and visual qualities.</p>
<p>Often these human whims to breed dogs with flattened faces, aggressive behaviour or short legs have had <a href="https://books.google.co.uk/books?hl=en&lr=&id=ZOoRn4KgIawC&oi=fnd&pg=PR15&dq=dog+breeds+cause+health+disease+problems&ots=DvEXITZ9XH&sig=ijj7VYNsAAMFPLSY7JfN-hzyER4#v=onepage&q=dog%2520breeds%2520cause%2520health%2520disease%2520problems&f=false">little or no regard</a> for the species’ <a href="https://www.sciencedirect.com/science/article/pii/S1558787809001348">long-term welfare</a>.</p>
<p>These standards reflect the values and desires of those who bred them and are particularly evident in three exhibits at the museum. The Silkie chicken originated in China and has fluffy plumage - bred to satisfy visual desires rather than Western appetites for <a href="https://www.aspca.org/sites/default/files/chix_white_paper_nov2015_lores.pdf">enormous breasted</a> factory-farmed chickens, which are bred for <a href="https://theinfluencers.org/en/center-for-postnatural-history/video/1">uniform size</a> to fit in processing machines. </p>
<p>The Center also has a stuffed mount of an “alcoholic” rat, bred to choose alcohol over water when given the choice, as part of a laboratory experiment by researchers in Finland to <a href="https://www.nature.com/articles/ncb437">help find a cure for alcoholism</a>. Then there’s “Freckles” – a stuffed goat bred by the company Nexia to produce spider silk in her milk as a potential <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1748-5967.2007.00121.x">replacement for Kevlar in military uniforms</a>.</p>
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<p>These three exhibits demonstrate how non-humans have been moulded to reflect human <a href="https://www.jstor.org/stable/622652?seq=1#metadata_info_tab_contents">expectations and desires</a>. The cultural systems which govern human life also increasingly apply to non-humans. It’s also no coincidence that the species discussed here have been bred in pursuit of profit, directly or indirectly. This suggests the pervasive influence of <a href="https://link.springer.com/article/10.1023/A:1006419715108">consumer capitalism</a> in human behaviour.</p>
<p>The most profitable organisms – such as cattle – have received the most investment and attention. The Belgian Blue cow, for example, has been bred for enormous, succulent and tasty shoulder and thigh muscles. But these mean <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1439-0531.2006.00825.x">Caesarean sections</a> are needed to avoid <a href="https://www.rspca.org.uk/adviceandwelfare/farm/beef/keyissues">birth canal blockages</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/267639/original/file-20190404-123405-tngn42.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Belgian Blue’s muscular build reflects consumer demand for succulent thigh and shoulder meat but causes severe health problems for the animal.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Spitzenbulle.JPG">Mastiff/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Profitable crop species are usually <a href="https://www.theguardian.com/environment/2017/oct/18/warning-of-ecological-armageddon-after-dramatic-plunge-in-insect-numbers">treated with pesticides to kill insects</a>, or <a>habitats are destroyed</a> to farm profitable species on. We leave little room for the species we haven’t exploited – <a href="https://www.ecowatch.com/biomass-humans-animals-2571413930.html">humans and livestock account for 96% of mammal biomass</a>.</p>
<p>This has created <a href="https://www.theguardian.com/environment/2014/sep/29/earth-lost-50-wildlife-in-40-years-wwf">dangerous imbalances in ecosystems</a>, while many of the species we exploit are being <a href="https://www.theguardian.com/news/2018/mar/12/what-is-biodiversity-and-why-does-it-matter-to-us">consumed faster than they can reproduce</a>. Humans have <a href="https://www.ufaw.org.uk/dogs/english-bulldog-dystocia">inserted themselves into the life cycles</a> of much of the living world, and these changes are heritable – their genetic trajectory is irreversibly set.</p>
<p>The Center for PostNatural History therefore shows us our collective power to shape the living world in our image. This power must be used responsibly.</p><img src="https://counter.theconversation.com/content/114800/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dominic Walker does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Human changes to the living world have benefited us, but the ecological consequences are mounting.Dominic Walker, Researcher in Cultural Geography, Royal Holloway University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/985952018-07-20T10:45:46Z2018-07-20T10:45:46ZPathogens attack plants like hackers, so my lab thinks about crop protection like cybersecurity<figure><img src="https://images.theconversation.com/files/228509/original/file-20180719-142417-14wj3wh.jpg?ixlib=rb-1.1.0&rect=541%2C44%2C2076%2C1633&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Plant hackers at work: microscopic oomycete spores infiltrating a plant root.</span> <span class="attribution"><span class="source">John Herlihy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Plants feed us. Without them we’re goners. Through thousands of years of genetic modification by selective breeding, humans have developed the crops that keep us alive. We have large kernels of grains, plump fruits and nutritious, toxin-free vegetables. These forms would never be found in nature, but were bred by people to keep us healthy and happy. </p>
<p>Unfortunately, microbes find our wonderfully productive food plants just as delicious as we do. These plant pathogens cause diseases that have changed world history and still affect us today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228470/original/file-20180719-142420-gduelt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">On the left, corn and its wild ancestor teosinte. Selective breeding has genetically modified crops to suit human needs. On the right, plant pathogen ergot on corn. We aren’t the only ones to subsist on our crops.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:On_Corn._Ergot_-_Flickr_-_gailhampshire.jpg">Left: Nicolle Rager Fuller, National Science Foundation, Right: gailhampshire</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These pathogens are plant hackers. Just like computer hackers, they’re specialized infiltrators, adept in stealth and disruption. The methods are the same, too: shut down defenses and access the target’s resources. Once they’re in, plant pathogens eat all they can and reproduce wildly. Computer hackers desire wealth or information, but the plant hackers are after our food. Up to <a href="https://doi.org/10.1094/PHI-I-2001-0425-01">25 percent of crops</a> globally are lost to diseases before they reach market. </p>
<h2>Oomycetes on the attack</h2>
<p>The most infamous and cunning plant hackers are the <a href="https://www.apsnet.org/edcenter/intropp/PathogenGroups/Pages/IntroOomycetes.aspx">oomycetes</a>. The <a href="http://www.bbc.co.uk/history/british/victorians/famine_01.shtml">Irish Potato Famine</a> in the 1840s was caused by the oomycete <a href="https://en.wikipedia.org/wiki/Great_Famine_(Ireland)#Blight_in_Ireland"><em>Phytophthora</em></a>, Greek for “plant destroyer.” This biological disaster led to the emigration of millions of people to the United States, and <a href="http://www1.assumption.edu/ahc/irish/overview.html">changed both countries</a> forever. Even today, oomycetes and the rest of the plant pathogens remain a barrier to <a href="http://www.fao.org/3/a-i6583e.pdf">global food security</a>, contribute to <a href="https://doi.org/10.3390/agriculture2030182">malnutrition</a> and <a href="https://doi.org/10.1016/j.fgb.2014.10.012">cost billions of dollars in losses annually</a>. </p>
<p>The oomycetes are a strange product of evolution. They look and behave like fungi; hence their Greek name “egg-fungus.” It wasn’t until the advent of gene sequencing that researchers correctly identified the oomycetes as a relative of algae, <a href="https://www.apsnet.org/edcenter/intropp/PathogenGroups/Pages/Oomycetes.aspx">not fungi</a>. Oomycetes start as single microscopic spores that infiltrate plant leaves or roots undetected. Once inside, they establish a perverse connection with the host plant’s cells. The hackers gain access and can mess around with anything they want – from switching off the plant’s security systems to breaking into stores of plant nutrients.</p>
<p>Evolution has given the oomycetes a repertoire of toxins and proteins that <a href="https://doi.org/10.1126/science.1203659">converge on hubs of the plant immune system</a> to disable it. Plants can fight back against these attacks if they recognize oomycete-specific chemicals or the hackers’ toxins. But detection is difficult and fleeting. The oomycetes hackers have genomes built for evolution. Core genes for metabolism and growth mutate and change at a normal pace. However, genes for toxins, and those that control infection are positioned to rearrange, combine or be turned off after a single generation. These new forms evolve so quickly that they baffle the slow-to-change plant immune system. This “<a href="https://dx.doi.org/10.1016/j.gde.2015.09.001">two-speed genome</a>” means the oomycetes always have a leg up on plant immune detection. When farmers use genetically identical crops year-to-year, oomycetes <a href="https://doi.org/10.1016/j.meegid.2013.10.017">don’t take long to evolve</a> around plants’ defenses.</p>
<p>So how do researchers and growers stop the plant hackers and help crops? Despite the cost and <a href="https://extension.psu.edu/potential-health-effects-of-pesticides">drawbacks</a>, <a href="https://doi.org/10.2478/v10102-009-0001-7">pesticide</a> has been an <a href="https://ipm.tamu.edu/about/pesticides/">important tool</a>
to control plant disease.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228473/original/file-20180719-142432-1wmv2d1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cucurbit downy mildew on watermelon.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Downy_mildew_on_watermelon_2.jpg">David B. Langston, University of Georgia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Farmers try to use minimum effective amounts of fungicide, which helps lower the chance oomycetes will develop resistance. For instance, the <a href="http://cdm.ipmpipe.org/">Cucurbit Downy Mildew Forecast Service</a> in Georgia combines reports of disease with weather forecasts to predict the likely path of disease spread. This allows growers to minimize sprays by sticking to high risk periods.</p>
<p>But it would be nice to have other weapons in the arsenal to fight off these plant hackers.</p>
<h2>Getting rid of exploitable loopholes</h2>
<p>In the <a href="https://fralin.vt.edu/Faculty/JohnMcDowell.html">McDowell lab</a> where I research here at Virginia Tech, we look for new ways to combat oomycete diseases.</p>
<p>Computer hackers rely on exploiting flaws in code to access systems and take what they want. Oomycetes work the same way, using their host to achieve their ends. For instance, <a href="https://doi.org/10.1126/science.1213351">plant diseases activate natural plant pumps</a> to supply sugar for their own growth. Some oomycetes have <a href="https://doi.org/10.1126/science.1195203">lost the capacity</a> to produce critical nutrients, meaning they rely on their plant host to do it for them. Without the plant host susceptibilities, the pathogen would starve before the plant got sick.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225800/original/file-20180702-116120-v888ys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Blue-stained omycete pathogen infecting transparent plant root cells.</span>
<span class="attribution"><span class="source">John Herlihy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>My colleagues and I study oomycete disease in the model plant <em>Arabidopsis</em>, more commonly called <a href="https://www.arabidopsis.org/portals/education/aboutarabidopsis.jsp">thale cress</a>. This weed is only grown in laboratories, but, like lab mice for humans, provides a tool to understand what goes on in our fields, orchards and gardens.</p>
<p>We focus on the relationships between plants and pathogens, looking for other ways oomycetes exploit their hosts. If we can identify the mechanisms of plant cell machinery that a pathogen requires to cause disease, we can breed or engineer plants to change, turn off or get rid of those vulnerabilities.</p>
<p>We test plants that have been genetically manipulated to turn off individual genes related to nutrient uptake, transport, storage and regulation. We infect these modified plants and look for any that are more resistant than their normal relatives. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228502/original/file-20180719-142428-1pofq5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Arabidopsis</em> seedlings before and after oomycetes infection. The white hairs on the infected plant on the right are spore-producing reproductive structures. The pillowy appearance gave the pathogen its name, downy mildew.</span>
<span class="attribution"><span class="source">John Herlihy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Often the removal of a gene is detrimental to the plant and the disease suffers as well. But occasionally we find a test plant that, despite its inactive gene, does just fine – and is less susceptible to the disease. Potentially, those plants lack a key component the pathogen requires to survive and grow. Finding those susceptibility genes and closing those exploitable holes in plant defense is my goal. </p>
<p>Looking forward, there is hope that research can diminish the impact of plant diseases. Like a computer, no plant defense system is perfect. However, if loopholes can be closed, hackers will have a much tougher time accessing what they’re after. Both breeding and genetic engineering provide paths to close those loopholes that may also exist in the vegetable crops that are most affected by plant hacking.</p>
<p>Even if everyone on Earth had enough to eat, a <a href="http://www.fao.org/3/a-i6583e.pdf">growing population</a>, increased <a href="https://foodsource.org.uk/book/export/html/41">demand for meat</a>, and a need for more <a href="https://avrdc.org/new-strategy-new-logo/">fresh produce</a> necessitates growing more food. This can either come from more farmland or more efficient farms. Strategies that employ <a href="https://insteading.com/blog/why-pesticides-are-actually-important-for-agricultural-sustainability/">limited pesticide</a> use along with plants that are more resilient to the pathogen hackers could make the farms we have more productive.</p><img src="https://counter.theconversation.com/content/98595/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Herlihy receives funding from the National Science Foundation. </span></em></p>Oomycete spores hack into plants to get what they need, causing agricultural disease. Can researchers figure out how to close plants’ security loopholes and create more resilient crops?John Herlihy, Ph.D. Student in the School of Plant and Environmental Science, Virginia TechLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/770452017-05-08T12:00:18Z2017-05-08T12:00:18ZScientists have mapped the DNA of tea – and it could stave off a pending crisis<figure><img src="https://images.theconversation.com/files/168356/original/file-20170508-20732-jvnxuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/@ravipinisetti?photo=ySQXoZLAsmc">Ravi Pinisetti/Unsplash</a></span></figcaption></figure><p>The world’s <a href="http://www.fao.org/economic/est/est-commodities/tea/en/">most popular drink</a> (after water) is under threat. We already know much about the threat of climate change to staple crops such as wheat, maize and rice, but the impact on tea is just coming into focus. Early research indicates that tea grown in some parts of Asia could see <a href="https://www.scientificamerican.com/article/global-warming-changes-the-future-for-tea-leaves/">yields decline</a> by up to 55% thanks to drought or excessive heat, and the quality of the tea is also falling.</p>
<p>The intensive use of pesticides and chemical fertilisers in tea plantations has also led to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2984095/">soil degradation</a> at an average annual rate of 2.8%. This also causes chemical runoff into waterways, which can lead to serious problems for human health and the environment.</p>
<p>However, hope may be on the horizon now that scientists at the Kunming Institute of Botany at the Chinese Academy of Sciences have <a href="http://bit.ly/2q7zvyi">sequenced the entire tea genome</a>. Mapping the exact sequence of DNA in this way provides the foundation for extracting all the genetic information needed to help breed and speed up development of new varieties of the tea plant. And it could even help improve the drink’s flavour and nutritional value.</p>
<p>In particular, the whole tea tree genome reveals the genetic basis for tea’s tolerance to environmental stresses, pest and disease resistance, flavour, productivity and quality. So breeders could more precisely produce better tea varieties that produce higher crop yields and use water and nutrients more efficiently. And they could do this while widening the genetic diversity of tea plants, improving the overall health of the tea plant population.</p>
<p>This is also an important milestone for scientists because it provides a deeper understanding of the complex evolution and the functions of key genes associated with stress tolerance, tea flavour and adaptation. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168363/original/file-20170508-20738-eu82um.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mmm, you can really taste the flavonoids.</span>
<span class="attribution"><a class="source" href="https://stocksnap.io/photo/B6CJ1F4MSR">Matthew Henry/Stocksnap</a></span>
</figcaption>
</figure>
<p>The new tea genome is very large, with nearly 37,000 genes – more than four times the size of the coffee plant genome. The process of evolution by natural selection has already helped the tea plant develop hundreds of genes related to resisting environmental stress from drought and disease.</p>
<p>These genes are like molecular markers that scientists can identify when selecting plants for use in breeding. This will allow them to be more certain that the next generation of plants they produce will have the genes and so the traits they want, speeding up <a href="https://link.springer.com/article/10.1007/s10681-010-0169-0">the breeding process</a>. Sequencing the genome also raises the possibility of using <a href="https://theconversation.com/how-gm-crops-can-help-us-to-feed-a-fast-growing-world-71112">genetic modification</a> (GM) technologies to turn on or enhance desirable genes (or turn off undesirable ones). </p>
<p>The same principles could also be used to enhance the nutritional or medicinal value of certain tea varieties. The genome sequence includes genes associated with biosynthesis. This is the production of the proteins and enzymes involved in creating the compounds that make tea so drinkable, such as <a href="http://www.ccsenet.org/journal/index.php/jfr/article/viewFile/45729/24980">flavonoids, terpenes and caffeine</a>. These are closely related to the aroma, flavour and quality of tea and so using genetic breeding techniques could help improve the taste of tea and make it more flavourful or nutritional.</p>
<p>For example, we could also remove the caffeine biosynthetic genes from the tea plant to help breeding of low or non-caffeine varieties. By boosting certain compounds at the same time, we could make tea healthier and develop entirely new flavours to make caffeine tea more appealing.</p>
<p>An estimated 5.56m tons of tea is commercially grown on more than 3.8m hectares of land (<a href="http://www.top-news.top/news-12896789.html">as of 2014</a>). And its huge cultural importance, as well as its economic value, mean securing a sustainable future for tea is vitally important for millions of people. So the first successful sequencing of the tea genome is a crucial step to making tea plants more robust, productive and drinkable in the face of massive environmental challenges.</p><img src="https://counter.theconversation.com/content/77045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chungui Lu does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sequencing the tea plant’s genome could help scientists breed new varieties that thrive in the degrading soil of tea farms.Chungui Lu, Professor of Sustainable Agriculture., Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/577892016-04-29T10:04:45Z2016-04-29T10:04:45ZTo fight Zika, let’s genetically modify mosquitoes – the old-fashioned way<p>The near <a href="http://www.who.int/emergencies/zika-virus/en/">panic caused by the rapid spread</a> of the <a href="http://www.who.int/mediacentre/factsheets/zika/en/">Zika virus</a> has brought new urgency to the question of how best to control mosquitoes that transmit human diseases. <em>Aedes aegypti</em> mosquitoes bite people across the globe, spreading three viral diseases: <a href="http://www.cdc.gov/dengue/">dengue</a>, <a href="http://www.cdc.gov/chikungunya/">chikungunya</a> and <a href="http://www.cdc.gov/zika/">Zika</a>. There are no proven effective vaccines or specific medications to treat patients after contracting these viruses.</p>
<p><a href="http://www.nytimes.com/aponline/2016/04/19/world/americas/ap-lt-zika-war-on-mosquito.html">Mosquito control</a> is the only way, at present, to limit them. But that’s no easy task. Classical methods of control such as insecticides are <a href="http://doi.org/10.3390/insects7010002">falling out of favor</a> – they can have adverse environmental effects as well as <a href="http://doi.org/10.1371/journal.ppat.1001000">increase insecticide resistance</a> in remaining mosquito populations. New <a href="http://www.thelancet.com/journals/langlo/article/PIIS2214-109X(16)00048-6/abstract">mosquito control methods are needed</a> – now.</p>
<p>The time is ripe, therefore, to explore a long-held dream of <a href="https://www.sciencedaily.com/terms/vector_(biology).htm">vector biologists</a>, including me: to use genetics to stop or limit the spread of mosquito-borne diseases. While gene editing technologies have advanced dramatically in the last few decades, it is my belief that we’ve overlooked older, tried and true methods that could work just as well on these insects. We can accomplish the goal of producing mosquitoes incapable of transmitting human pathogens using the same kinds of selective breeding techniques people have been using for centuries on other animals and plants.</p>
<h2>Techniques on the table</h2>
<p>One classic strategy for reducing insect populations has been to <a href="http://doi.org/10.1007/1-4020-4051-2">flood populations with sterile males</a> – usually produced using irradiation. When females in the target population mate with these males, they produce no viable offspring – hopefully crashing population numbers.</p>
<p>The modern twist on this method has been to generate transgenic males that carry a dominant lethal gene that essentially makes them sterile; offspring sired by these males die late in the larval stage, eliminating future generations. This method has been promulgated by the <a href="http://www.oxitec.com/ridl-science/">biotech company Oxitec</a> and is currently <a href="http://dx.doi.org/10.1371/journal.pntd.0003864">used in Brazil</a>.</p>
<p>Rather than just killing mosquitoes, a more effective and lasting strategy would be to genetically change them so they can no longer transmit a disease-causing microbe.</p>
<p>The powerful new CRISPR gene editing technique could be used to make transgenes (genetic material from another species) take over a wild population. This method <a href="http://dx.doi.org/10.1016/j.celrep.2015.03.009">works well in mosquitoes</a> and is potentially a way to <a href="http://doi.org/10.1534/genetics.115.177592">“drive” transgenes into populations</a>. CRISPR could help quickly spread a gene that confers resistance to transmission of a virus – what scientists call refractoriness.</p>
<p>But CRISPR has been controversial, especially as applied to human beings, because the transgenes it inserts into an individual can be passed on to its offspring. No doubt using CRISPR to create and release genetically modified mosquitoes into nature would stir up controversy. The U.S. Director of National Intelligence, James Clapper, has gone so far as to <a href="https://www.technologyreview.com/s/600774/top-us-intelligence-official-calls-gene-editing-a-wmd-threat/">dub CRISPR a potential weapon of mass destruction</a>.</p>
<p>But are transgenic technologies necessary to genetically modify mosquito populations?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Examples of successful artificial selection of various traits through the years. In the center is a cartoon of the ‘block’ scientists would like to select for in mosquitoes so they can’t pass on the virus.</span>
<span class="attribution"><span class="source">Jeff Powell</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Selective breeding the old-fashioned way</h2>
<p>Genetic modification of populations has been going on for centuries with great success. This has occurred for almost all commercially useful plants and animals that people use for food or other products, including cotton and wool. Selective breeding can produce immense changes in populations based on naturally occurring variation within the species.</p>
<p>Artificial selection using this natural variation has proven effective over and over again, especially in the agricultural world. By choosing parents with desirable traits (chickens with increased egg production, sheep with softer wool) for several consecutive generations, a “true breeding” strain can be produced that will always have the desired traits. These may look very different from the ancestor – think of all the breeds of dogs derived from an ancestor wolf.</p>
<p>To date, only limited work of this sort has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/3834805">done on mosquitoes</a>. But it does show that it’s possible to select for mosquitoes with reduced ability to transmit human pathogens. So rather than introducing transgenes from other species, why not use the genetic variation naturally present in mosquito populations?</p>
<p>Deriving strains of mosquitoes through artificial selection has several advantages over transgenic approaches.</p>
<ul>
<li>All the controversy and potential risks surrounding transgenic organisms (GMOs) are avoided. We’re only talking about increasing the prevalence in the population of the naturally occurring mosquito genes we like.</li>
<li>Selected mosquitoes derived directly from the target population would likely be more competitive when released back to their corner of the wild. Because the new refractory strain that can’t transmit the virus carries only genes from the target population, it would be specifically adapted to the local environment. Laboratory manipulations to produce transgenic mosquitoes are known to <a href="http://doi.org/10.1073/pnas.0305511101">lower their fitness</a>.</li>
<li>By starting with the local mosquito population, scientists could select specifically for refractoriness to the virus strain infecting people at the moment in that locality. For example, there are four different “varieties” of the dengue virus called serotypes. To control the disease, the selected mosquitoes would need to be refractory to the serotype active in that place at that time.</li>
<li>It may be possible to select for strains of mosquitoes that are unable to transmit multiple viruses. Because the same <em>Aedes aegypti</em> mosquito species transmits dengue, chikungunya and Zika, people living in places that have this mosquito are simultaneously at risk for all three diseases. While it has not yet been demonstrated, there is no reason to think that careful, well-designed selective breeding couldn’t develop mosquitoes unable to spread all medically relevant viruses.</li>
</ul>
<p>Fortunately, <em>Ae. aegypti</em> is the easiest mosquito to rear in captivity and has a generation time of about 2.5 weeks. So unlike classical plant and animal breeders dealing with organisms with generations in years, 10 generations of selection of this mosquito would take only months.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers are working out mass rearing techniques for Aedes mosquitoes – their generation time is only 2.5 weeks.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/iaea_imagebank/25015286483">IAEA Imagebank</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>This is not to imply there may not be obstacles in using this approach. Perhaps the most important is that the genes that make it hard for these insects to transmit disease may also make individual insects weaker or less healthy than the target natural population. Eventually the lab-bred mosquitoes and their offspring could be out-competed and fade from the wild population. We might need to continuously release refractory mosquitoes – that is, the ones that aren’t good at transmitting the disease in question – to overcome selection against the desirable refractory genes.</p>
<p>And mosquito-borne pathogens themselves evolve. Viruses may mutate to evade any genetically modified mosquito’s block. Any plan to genetically modify mosquito populations needs to have contingency plans in place for when viruses or other pathogens evolve. New strains of mosquitoes can be quickly selected to combat the new version of the virus – no costly transgenic techniques necessary.</p>
<p>Today, plant and animal breeders are increasingly using new gene manipulation techniques to further improve economically important species. But this is only after traditional artificial selection has been taken about as far as it can to improve breeds. Many mosquito biologists are proposing to go directly to the newest fancy transgenic methodologies that have never been shown to actually work in natural populations of mosquitoes. They are skipping over a proven, cheaper and less controversial approach that should at least be given a shot.</p><img src="https://counter.theconversation.com/content/57789/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Powell receives funding from the US National Institutes of Health </span></em></p>Look beyond transgenic techniques that add new genes to a species. People have used selective breeding techniques to change plants and animals for millennia – why not try them on mosquitoes?Jeffrey Powell, Professor, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/561132016-03-11T15:02:36Z2016-03-11T15:02:36ZWhy dog breeds aren’t considered separate species<figure><img src="https://images.theconversation.com/files/114740/original/image-20160310-26248-1dlu2cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Susan Schmitz / shutterstock</span></span></figcaption></figure><p>Dog owners might disagree, but as far as evolutionary biologists are concerned, all dogs are just dogs. It may seem odd that <em>Canis (lupus) familiaris</em> extends from rabbit-sized Chihuahuas to Great Danes which can be almost the size of a small pony, whereas seemingly much smaller differences place many animals into separate species or sub-species. One has to dig a bit into evolutionary theory for this to make sense.</p>
<p>The dog is <a href="http://www.pbs.org/wgbh/evolution/library/01/5/l_015_02.html">a direct descendant</a> of the grey wolf (<em>Canis lupus</em>), with evidence that lots of different wolves fed into the dog gene pool over the years. In the course of dog domestication, their behaviour, morphology and physique has changed, and differences among dog breeds are indeed astonishing. Imagine if future palaeontologists were to find Chihuahua remains in the fossil record: this animal would appear to have little in common with wolves. </p>
<p>But these differences among dog breeds – and between dogs and wolves – aren’t enough to warrant recognition as distinct species. Dogs are simply too young, from an evolutionary perspective.</p>
<p>It usually takes hundreds of thousands of years or more for mammals to evolve into distinct new species, requiring the slow accumulation of mutations that cause inheritable changes to its physical characteristics – or “phenotype”. Archaeological data and analysis of DNA from today’s dogs and wolves, as well as ancient remains, suggest that domestication started about <a href="http://dx.doi.org/10.1016/j.cub.2015.04.019">16,000-40,000 years ago</a>, with most current dog breeds originating in the past 200 years.</p>
<h2>We’ve sped up dog evolution – but not enough</h2>
<p>Charles Darwin pointed out that humans have accelerated the process of selection by choosing particular individuals for breeding, based on certain desired characteristics – what we call <a href="http://evolution.berkeley.edu/evolibrary/article/evo_30">artificial selection</a>. Natural selection generally requires much more time, because it acts on novel variants introduced into the gene pool through the slow process of chance DNA mutation. Nevertheless, the power of artificial selection in generating extreme phenotypes does not change the fundamental fact that dog breeds have been separated for only a short evolutionary time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=504&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=504&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=504&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=633&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=633&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114774/original/image-20160311-11288-mfueq9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=633&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Great Dane, meet Chihuahua. You have lots in common.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Big_and_little_dog_1.jpg">Ellen Levy Finch</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This means that dog breeds differ drastically in their appearance and other characteristics, while most of their genomes are still very much alike. Comparing different breeds, most of their genomes indeed show only little differentiation. In other words, Chihuahuas and Great Danes are overall very similar to one another. The vast physical differences are largely driven by relatively few loci (regions) in the genome. These loci have a large phenotypic effect, leading to strong differentiation among breeds. </p>
<p>This is particularly interesting for evolutionary biologists, and pinpointing such regions in the genome has for example recovered the genetic basis of <a href="http://www.nature.com/news/2006/061009/full/news061009-12.html">size variation among dog breeds</a>. We now also have an understanding of the mutations that control traits such as <a href="http://science.sciencemag.org/content/326/5949/150">coat characteristics</a> and <a href="http://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-015-1702-2">ear floppiness</a>.</p>
<h2>Dog breeds are artificial and potentially temporary</h2>
<p>So if breeds are that similar to one another in their genomes, how are the vast differences maintained? The obvious answer is the mating pattern we impose on our dogs – we keep breeds separate by preventing interbreeding between them. </p>
<p>The fact humans keep them apart is crucial here. Species are <a href="http://darwiniana.org/mayrspecies.htm">commonly defined</a> as “groups of interbreeding natural populations that are reproductively isolated from other such groups”. This requires hybrids between distinct species to either be non-viable (such as the proposed “humanzee”), or for their offspring to be infertile like most mules, or the more exotic “ligers”. In both these cases there would be complete reproductive isolation between the two groups, whether they be humans and chimps, lions and tigers, or Labradors and poodles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114838/original/image-20160311-11274-1troby6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Labrador (right) + poodle = the fluffy and fertile labradoodle (left).</span>
<span class="attribution"><span class="source">Bildagentur Zoonar GmbH / shutterstock</span></span>
</figcaption>
</figure>
<p>Yet two entirely different dogs will produce perfectly fertile offspring, and many modern breeds in fact originated in this way. Of course in some cases other factors might make mating very tricky. A female Chihuahua would have trouble naturally delivering a male Great Dane’s offspring, for instance. But though some breeds would never mate with each other without human intervention, middle-sized breeds could provide the link between extremely large and small dogs. </p>
<p>Street dogs are a vivid illustration of this point – they show how the distinct gene pools of dog breeds can rapidly mix once the restrictions of artificial breeding are removed. Moscow’s <a href="https://theconversation.com/how-did-moscows-stray-dogs-learn-to-navigate-the-metro-54790">famous feral dogs</a> have existed separate from purebred pets for at least 150 years now. In this time they have largely lost features like the spotty colouration that distinguish one breed from another, or the wagging tails and friendly behaviour towards humans that distinguish dogs from wolves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=430&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=430&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114777/original/image-20160311-11302-b7aky3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=430&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left to their own devices, street dogs soon stop looking like distinct breeds.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/akras/2299311609/in/album-72157604174353563/">Andrey</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>So genetic exchange would still be common among dog breeds, were they allowed to reproduce freely. In that sense, dog breeds would not be classified as separate species under most definitions. If those Chihuahuas and Great Danes don’t look like the same species right now, it’s only because humans are constantly maintaining a barrier between them.</p><img src="https://counter.theconversation.com/content/56113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frank Hailer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’ve bred them into all shapes and sizes, but dogs haven’t been around for long enough to have evolved beyond Canis familiaris.Frank Hailer, Lecturer in Evolutionary Biology, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/478202015-12-02T11:05:25Z2015-12-02T11:05:25ZWhat clues does your dog’s drool hold for human mental health?<figure><img src="https://images.theconversation.com/files/103945/original/image-20151201-26568-1ld7n8o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There goes some precious DNA....</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/graemebird/2478467142">Graeme Bird</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Dogs were the <a href="https://theconversation.com/new-dna-analysis-says-your-poochs-ancestors-were-central-asian-wolves-49271">first animals people domesticated</a>, long before the earliest human civilizations appeared. Today, tens of thousands of years later, dogs have an unusually close relationship with us. They share our homes and steal our hearts – and have even evolved <a href="http://barkpost.com/dogs-love-us-like-family/">to love us back</a>. Sadly, they also suffer from many of the same difficult-to-treat psychiatric and neurological diseases we do.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=733&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=733&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=733&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=921&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=921&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103939/original/image-20151201-26582-1tcleck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=921&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Beskow, in fine spirits.</span>
<span class="attribution"><span class="source">Elinor Karlsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>I learned this firsthand about six years ago, when my sister Adria adopted Beskow, a beautiful, boisterous, black and white mutt. Beskow became my constant companion on my morning runs along the Charles River. Her joy in running was obvious to everyone we passed, and she kept me going mile after mile. </p>
<p>When not running, though, Beskow suffered from constant anxiety that left her stressed and unhappy – on edge around other dogs and prone to aggressive behavior. Beskow had trouble even playing outdoors, since she was compelled to attend to every sound and movement. Working one-on-one with skilled behaviorists and trainers helped immensely, but poor Beskow still never seemed able to relax. Eventually, Adria combined the intensive training with medication, which finally seemed to give Beskow some relief. </p>
<p>Beskow’s personality – her intelligence, her focus and her anxiety – was shaped not only by her own life experiences, but by thousands of years of evolution. Have you ever known a dog who would retrieve the same ball over and over again, for hours on end? Or just wouldn’t stay out of the water? Or wasn’t interested in balls, or water, but just wanted to follow her nose? These dogs are the result of hundreds of generations of artificial selection by human beings. By favoring useful behaviors when breeding dogs, we made the genetic changes responsible more common in their gene pool.</p>
<p>When a particular genetic change rapidly rises in prevalence in a population, it leaves a “signature of selection” that we can detect by sequencing the DNA of <a href="http://genomesunzipped.org/2010/09/detecting-positive-natural-selection-from-genetic-data.php">many individuals from the population</a>. Essentially, around a selected gene, we find a region of the genome where one particular pattern of DNA – the variant linked to the favored version of the gene – is far more common than any of the alternative patterns. The stronger the selection, the bigger this region, and the easier it is to detect this signature of selection. </p>
<p>In dogs, genes shaping behaviors purposely bred by humans are marked with large signatures of selection. It’s a bit like evolution is shining a spotlight on parts of the dog genome and saying, “Look here for interesting stuff!” To figure out exactly how a particular gene influences a dog’s behavior or health, though, we need lots more information. </p>
<p>To try to unravel these connections, my colleagues and I are launching a new citizen science research project we’re calling <a href="http://darwinsdogs.org/">Darwin’s Dogs</a>. <a href="http://iaabc.org/">Together with animal behavior experts</a>, we’ve put together a series of short surveys about everything from diet (does your dog eat grass?) to behavior (is your dog a foot sitter?) to personality (is your dog aloof or friendly?). </p>
<p>Any dog can participate in <a href="http://darwinsdogs.org/">Darwin’s Dogs</a>, including purebred dogs, mixed breed dogs, and mutts of no particular breed – our study’s participants will be very genetically diverse. We’re combining <a href="http://doi.org/10.1016/j.cell.2013.09.006">new DNA sequencing technology</a>, which can give us much more genetic information from each dog, with powerful new <a href="http://doi.org/10.1038/nrg3382">analysis methods that can control for diverse ancestry</a>. By including all dogs, we hope to be able to do much larger studies, and home in quickly on the important genes and genetic variants. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103941/original/image-20151201-26574-6ny0rs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A beagle considers making the saliva donation.</span>
<span class="attribution"><span class="source">Stephen Schaffner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Once an owner has filled out the survey, there’s a second, crucial step. We send an easy-to-use kit to collect a small dog saliva sample we can use for DNA analysis. There’s no cost, and we’ll share any information we find.</p>
<p>Our plan is to combine the genetic data from many dogs and look for changes in DNA that correlate with particular behaviors. It won’t be easy to match up DNA with an obsession with tennis balls, for instance. Behavior is a complex trait that relies on many genes. Simple <a href="http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593">Mendelian traits</a>, like Beskow’s black and white coat, are controlled by a single gene which determines the observable characteristic. This kind of inherited trait is comparatively easy to map. Complex traits, on the other hand, may be shaped by tens or even hundreds of different genetic changes, each of which on its own only slightly alters the individual carrying it. </p>
<p>Adding to the complexity, environment often plays a big role. For example, Beskow may not have been as anxious if she’d lived with Adria from puppyhood, even though her genetics would be unchanged. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=648&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=648&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=648&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=814&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=814&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103946/original/image-20151201-26546-hlyirx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=814&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Darwin’s Dogs team member Jesse McClure extracts DNA from a sample.</span>
<span class="attribution"><span class="source">Elinor Karlsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To succeed, we need a lot of dogs to sign up. Initially, we’re aiming to enroll 5,000 dogs. If successful, we’ll keep growing. With bigger sample sizes, we’ll be able to tackle even more complex biological puzzles. </p>
<p>This is a huge effort, but could offer huge rewards. By figuring out how a genetic change leads to a change in behavior, we can decipher neural pathways involved in psychiatric and neurological diseases <a href="http://doi.org/10.1016/S0278-5846(00)00104-4">shared between people and dogs</a>. We already know these include not just anxiety, but also <a href="http://www.nytimes.com/2011/12/02/us/more-military-dogs-show-signs-of-combat-stress.html">PTSD</a>, <a href="http://doi.org/10.1186/gb-2014-15-3-r25">OCD</a>, <a href="http://doi.org/10.1038/tp.2014.106">autism spectrum disorders</a>, <a href="http://doi.org/10.2460/javma.2001.219.467">phobias</a>, <a href="http://doi.org/10.1016/S0092-8674(00)81965-0">narcolepsia</a>, <a href="http://doi.org/10.1111/epi.12138">epilepsy</a>, <a href="http://doi.org/10.1016/0197-4580(95)02060-8">dementia and Alzheimer’s disease</a>.</p>
<p>Understanding the biology underlying a disease is the first step in developing more effective treatments – of both the canine and human variety. For example, <a href="http://doi.org/10.1016/S0092-8674(00)81965-0">genetic studies of narcolepsy in Doberman pinschers</a> found the gene mutation causing the disease – but only in this one dog population. Researching the gene’s function, though, led to critical new insights into the molecular biology of sleep, and, eventually, to <a href="http://dx.doi.org/10.2147/NSS.S56077">new treatment options for people</a> suffering from this debilitating disease. </p>
<p><a href="http://darwinsdogs.org">Darwin’s Dogs</a> is investigating normal canine behaviors as well as diseases. We hypothesize that finding the small genetic changes that led to complex behaviors, like retrieving, or even personality characteristics, like playfulness, will help us figure out how brains work. We need this mechanistic understanding to design new, safe and more effective therapies for psychiatric diseases. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103943/original/image-20151201-26582-7fy2k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Beskow with one of her loving family members.</span>
<span class="attribution"><span class="source">Adria Karlsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>And Beskow? Six years later, she is as wonderful as ever. While still anxious some of the time, the medication and training have paid off, and she enjoys her daily walks, training and playtime. She still gets very nervous around other dogs, but is a gentle, playful companion for my sister’s three young children.</p>
<p>We are now sequencing her genome. In the next few months, we should have our first glimpse into Beskow’s ancestry. We know she is a natural herder, so we’re curious to find out how much her genome matches up to herding breeds, and which genes are in that part of the genome.</p>
<p>Of course, we can’t figure out much from just one dog – if you are a dog owner, please <a href="http://darwinsdogs.org">enroll your dog today</a>!</p><img src="https://counter.theconversation.com/content/47820/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elinor Karlsson receives funding from the NIH and the Worcester Foundation.</span></em></p>Researchers want your canine’s DNA to help unravel the connections between genes and behavior – for dogs and human beings.Elinor Karlsson, Assistant Professor of Bioinformatics and Integrative Biology, UMass Chan Medical SchoolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/395322015-04-10T09:47:51Z2015-04-10T09:47:51ZNot all GMO plants are created equally: it’s the trait, not the method, that’s important<figure><img src="https://images.theconversation.com/files/77560/original/image-20150409-15231-13zm7ko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cornfield, GMO or not?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/katieharbath/4809776181">Katie Harbath</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Many people have strong opinions about genetically modified plants, also known as genetically modified organisms or GMOs. But sometimes there’s confusion around what it means to be a GMO. It also may be much more sensible to judge a plant by its specific traits rather than the way it was produced – GMO or not. </p>
<p>This article is not about judging whether GMOs are good or bad, but rather an explanation of how plants with modified genomes are made. (There are non-plant GMOs, but in this article we will only refer to plant GMOs.) First of all, it’s necessary to define what we mean by a GMO. For the purposes of this discussion, I’m defining GMOs as plants whose genetic information (found in their genomes) has been modified by human activity.</p>
<h2>Humans have changed the genomes of virtually all the plants in the grocery store</h2>
<p>If we think of GMOs as plants that have genomes modified by humans, then quite a lot of the plants sold in any grocery store fit that description. But many of these modifications didn’t occur in the lab. Farmers select plants with superior, desirable traits to cultivate in a process known as <a href="http://dx.doi.org/10.1104/pp.126.1.8">agricultural evolution</a>. Thousands of years of traditional agricultural breeding has changed plant genomes from those of their original wild ancestors. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77381/original/image-20150408-18057-56zb3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wild cabbage doesn’t look much like its domesticated version, broccoli.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nturland/7291619104">Nicholas Turland</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Broccoli, for example, is not a naturally occurring plant. It’s been bred from <a href="http://dx.doi.org/10.1007/BF02862698">undomesticated <em>Brassica oleracea</em></a> or ‘wild cabbage’; domesticated varieties of <em>B. oleracea</em> include both broccoli and cauliflower. Broccoli, along with any seedless variety of fruit (<a href="http://www.popsci.com/scitech/article/2008-06/can-fruit-be-saved">including what you think of as bananas</a>), and most of the crops grown on farms today would not exist without human intervention. </p>
<p>However, these aren’t the plants that people typically think of when they think of GMOs. It’s easy to understand how farmers can breed better plants on farms (by choosing to plant seeds from the biggest or best-yielding plants, for example, imposing <a href="http://learn.genetics.utah.edu/content/selection/artificial/">artificial selection</a> on the crop species) so even though this activity changes plant genomes in ways nature wouldn’t have, most people don’t consider these plants GMOs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77383/original/image-20150408-18086-ja40u2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scientists training in marker-assisted backcrossing selection technique.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/icrisat/7595881154">ICRISAT/CT. Hash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Creating “lab” GMOs</h2>
<p>Once plant genes had been studied enough, researchers could turn to <a href="http://dx.doi.org/10.1104/pp.108.118232">backcrossing</a>. This technique involves breeding the offspring back with the parents to try to get a desired, stable combination of parental traits. Genes previously linked to desirable plant traits, such as higher yield or pest-resistance, could be identified and screened for using molecular biology techniques and linkage maps. These maps lay out the relative position of genes along a chromosome, based on how often they are passed along together to offspring. Closer genes tend to travel together. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1132&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1132&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77563/original/image-20150409-15219-t69s2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1132&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tiny experimental trees grown from lab-cultured cells in which researchers inserted new genes.</span>
<span class="attribution"><a class="source" href="http://www.ars.usda.gov/is/graphics/photos/k5011-19.htm">Scott Bauer</a></span>
</figcaption>
</figure>
<p>Researchers used molecular markers – specific, known gene sequences, present in the linkage maps – to select individual plants that contained both the new marker gene and the greatest proportion of other favorable genes from the parents. The combinations of genes passed to offspring are always due to random recombination of the parents’ genes. Researchers weren’t able to drive particular combinations themselves, they had to work with what arose naturally; so in this <a href="http://dx.doi.org/10.1098/rstb.2007.2170">marker-assisted selection</a> approach, there’s a lot of effort and time spent trying to find plants with the best combinations of genes.</p>
<p>In this system, a laboratory needs to screen the genomes, using molecular biology methods to look for particular gene sequences for desirable traits in the bred offspring. Sometimes a lab even breeds the plants in cases using <a href="http://www.elsevier.com/books/plant-tissue-culture-theory-and-practice/bhojwani/978-0-444-81623-8">tissue culture</a> – a way to propagate many plants simultaneously while minimizing the resources needed to grow them. </p>
<h2>Inserting non-plant genes into GMOs</h2>
<p>In the early 1980s, the plant biotechnology era began with <em>Agrobacterium tumifaciens</em>. This bacterium naturally infects plants and, in the wild, creates tumors by transferring DNA between itself and the plant it has infected. Scientists use this natural property to <a href="http://dx.doi.org/10.2225/vol1-issue3-fulltext-1">transfer genes</a> to plant cells from an <em>A. tumifaciens</em> bacterium modified to contain a gene of interest.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=760&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=760&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=760&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=956&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=956&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77384/original/image-20150408-18075-1gialxm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=956&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Agrobacterium tumefaciens</em> as they begin to infect a carrot cell.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Agrobacterium-tumefaciens.png">A G Matthysse, K V Holmes, R H G Gurlitz</a></span>
</figcaption>
</figure>
<p>For the first time, it was possible to insert specific genes into a plant genome, even genes that do not come from that species – or even from a plant. <em>A. tumifaciens</em> does not affect all plants, however, so researchers went on to develop DNA-transferring methods inspired by this system which would work without it. They include microinjection and “gene guns,” where the desired DNA was <a href="http://dx.doi.org/10.1038/325274a0">physically injected</a> into the plant, or covered tiny particles that were literally <a href="http://dx.doi.org/10.1016/0167-7799(88)90023-6">shot into the nuclei of plant cells</a>.</p>
<p>A recent review <a href="http://dx.doi.org/10.1111/tpj.12413">summarizes eight new methods for altering genes in plants</a>. These are molecular biology techniques that use different enzymes or nucleic acid molecules (DNA and RNA) to make changes to a plant’s genes. One route is to alter the sequence of a plant’s DNA. Another is to leave the sequence alone but make other <a href="http://dx.doi.org/10.1016/j.pbi.2010.12.002">epigenetic modifications</a> to the structure of a plant’s DNA. For instance, scientists could add arrangements of atoms called methyl groups to some of the nucleotide building blocks of DNA. These epigenetic modifications, while not altering the order of the DNA or of genes, <a href="http://www.nature.com/scitable/topicpage/the-role-of-methylation-in-gene-expression-1070">change how genes can be expressed</a> and thus the observable traits a plant has. </p>
<h2>GMO doesn’t mean glyphosate-resistant</h2>
<p>Calling a plant a genetically modified organism means only that – its genome has been modified by the activity of humans. But lots of people conflate the idea of a GMO plant with one that’s been created to be resistant to the herbicide glyphosate, also known by the brand name Roundup. It’s true that the most well-known GMO crops currently grown contain a gene that makes them resistant to glyphosate, which allows farmers to spray the chemical to kill weeds while allowing their crop to grow. But that’s just one example of a gene inserted into a plant. </p>
<p>It’s sensible to evaluate GMOs not on how they are made, but rather on <a href="http://dx.doi.org/10.1111/tpj.12413">what new traits the modified plants have</a>. For instance, while it can be argued that glyphosate resistance in plants is not good for the environment because of <a href="http://dx.doi.org/10.1186/2190-4715-24-24">increased use of the pesticide</a>, other GMOs are unlikely to cause this problem. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77380/original/image-20150408-18089-zab3i7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Golden rice (on the right) compared to white rice.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Golden_Rice.jpg">International Rice Research Institute</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>For example, it’s difficult see how the controversial <a href="http://dx.doi.org/10.1104/pp.125.3.1157">golden rice</a>, which has been engineered to produce vitamin A in the rice grains to be more nutritious, is worse for the environment than ordinary rice. GMOs have been developed to express a pesticide permitted in organic farming: <a href="http://www2.ca.uky.edu/entomology/entfacts/ef130.asp">Bt toxin</a>, an insecticide naturally produced by the bacterium <em>Bacillus thuringiensis</em>. While this may reduce pesticide use, it may also lead to the <a href="http://dx.doi.org/10.1186/2190-4715-24-24">evolution of Bt-resistant insects</a>. And there are GMOs which have improved storage characteristics or nutritional content, like <a href="http://dx.doi.org/10.3733/ca.v054n04p6">“Flavr Savr” tomatoes</a>, or <a href="http://m.apnews.com/ap/db_289563/contentdetail.htm?contentguid=YOuzt2GL">pineapples that contain lycopene, and tomatoes that contain anthocyanins</a>. These compounds are ordinarily found in other fruits and are thought to have <a href="http://dx.doi.org/10.1016/S0002-8223(00)00420-X">health benefits</a>. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77565/original/image-20150409-15244-12bc0db.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">GMOs that include different species’ genes make some people uncomfortable.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/elizaio/5608032236">elizaIO</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The so-called <a href="https://e-class.teilar.gr/modules/document/file.php/FP103/3.pdf">“fish tomato”</a> contains an antifreeze protein (gene name <em>afa3</em>), found naturally in winter flounder, that increases frost tolerance in the tomato plant. The tomato doesn’t actually contain fish tissue, or even necessarily DNA taken from fish tissue – just DNA of the same sequence present in the fish genome. The Afa3 protein is produced from the <em>afa3</em> gene in the tomato cells using the same machinery as other tomato proteins. </p>
<p>Is there any fish in the tomato plant? Whether DNA taken from one organism and put into another can change the species of the recipient organism is an interesting philosophical debate. If a single gene from a fish can make a “fish tomato” a non-plant, <a href="http://www.iflscience.com/plants-and-animals/almost-150-our-genes-may-have-come-microbes">are we human beings, who naturally contain over a hundred non-human genes,</a> truly human?</p><img src="https://counter.theconversation.com/content/39532/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Bent receives funding from the Ontario Ministry of Agriculture and Food, and the Natural Sciences and Engineering Research Council of Canada. She consults to her own company, Renaissance Biological Solutions, Inc. She is a molecular biologist and microbiologist, and does not work with or research genetically modified plants, or have relationships with any company or organization promoting the use of genetically modified plants. </span></em></p>People have been changing plant genomes ever since agriculture got started thousands of years ago. Here are the high-tech ways researchers insert new genes into plants now.Elizabeth Bent, Research Associate, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/332972014-10-28T19:07:54Z2014-10-28T19:07:54ZHow to hit the genetic jackpot and breed a Melbourne Cup winner<p>The win of Japanese stayer <a href="http://www.theage.com.au/sport/horseracing/caulfield-cup-2014-admire-rakti-storms-home-to-win-3m-cup-20141018-11862s.html">Admire Rakti</a> in the Caulfield Cup, followed by Irish bred colt <a href="http://www.abc.net.au/news/2014-10-25/adelaide-wins-the-cox-plate/5841668">Adelaide</a>’s win in the Cox Plate last Saturday, has brought into question the stamina (staying) credentials of Australian bred racehorses.</p>
<p>It seems <a href="http://www.abc.net.au/news/2014-10-28/horse-breeding-distance-28-10-14/5847056">less and less likely</a> that an Australian bred horse will win another Melbourne Cup, and most people involved in horseracing will tell you that Australian horses are not bred to win over long distances. </p>
<p>So, what are they bred to do? And how does someone go about breeding a Melbourne Cup winner?</p>
<p>The major factors usually taken into consideration by breeders when planning matings are racing performance, pedigree and the conformation (size and shape) of the horse. The horses that have won the best races clearly had the right genetics to do so, and it is assumed they will pass these genes on to the next generation. </p>
<h2>The body beautiful</h2>
<p>“Breed the best to the best and hope for the best” is an old Thoroughbred breeding adage which is still often referred to today. </p>
<p>A horse’s pedigree is traditionally considered to be of utmost importance. By assessing the performance of close relatives, breeders can get an idea of the likely genetic merit of their horse. This is particularly important when a horse does not race due to an accident or illness. </p>
<p>Pedigree analysis is also a strategy used to plan matings. There are many breeding theories (such as <a href="http://www.chef-de-race.com/dosage/review.htm">Dosage</a>, the <a href="http://www.pedigreepost.net/archives/XFactorDWDavidge.html">X-factor</a> and <a href="http://www.thoroughbredreview.com/nicking.htm">Nicks</a>) that identify matings that are most likely to produce a foal with the right combination of complimentary genes from their parents. </p>
<p>Good conformation is also significant. In Australia, much emphasis is placed on the horse being a reasonable size, with strong straight legs, clean joints and a good amount of muscle. </p>
<p>This build is indicative of a higher proportion of fast twitch muscle fibres, which are responsible for power and speed, particularly over shorter distances. Stayers, such as Melbourne Cup winners, tend to be the opposite build, and are often tall, long and lean. You can liken these to the differences in the build of the muscular sprinter Usain Bolt versus the exceptionally lean marathon runner Steve Moneghetti. </p>
<h2>Impact of pedigree</h2>
<p>But to what degree are any of these traits heritable? Does pedigree actually relate to racing ability? </p>
<p>Well, genetics only accounts for around 30% of <a href="http://www.ncbi.nlm.nih.gov/pubmed/24467785">racing performance</a>, with the rest influenced by environmental factors such as nutrition, trainer, track surface and, of course, luck. </p>
<p>We have recently assessed the relative contribution of genetics to certain performance traits in Australian Thoroughbreds. We found that winning times tend not to be influenced by pedigree, while earnings are moderately influenced. The trait most influenced by pedigree is called “best race distance”. </p>
<p>Best race distance is the distance at which a horse won its best (highest grade) race. In Australia, flat races are generally between 1,000m and 3,200m long. The world’s richest race for two-year-olds, the Golden Slipper, is 1,200m, while the Melbourne Cup is 3,200m. </p>
<p>Australia’s racing and breeding industry is generally aimed at producing elite sprinters that are at their best over the 1,200m of the Golden Slipper. Black Caviar won 18 of her 25 races at 1,200m. </p>
<h2>Testing times</h2>
<p>These days, you don’t even have to wait until your horse has started its racing career to find out what its best race distance is likely to be. </p>
<p>Before the foal is even weaned, you can just pull out some mane hairs and send them to one of the Thoroughbred DNA testing laboratories for analysis. They can tell you whether your horse is likely to be a stayer or a sprinter, what height it will be and if it is likely to be an elite performer. </p>
<p>These companies have analysed the DNA of elite racehorses and identified sections of DNA that are associated with performance traits. Emmeline Hill’s <a href="http://www.equinome.com/News">Equinome</a> was the first to relate the myostatin gene with best race distance. She showed that a “marker” in this gene was related not only to sprinting performance, but also to the amount of muscle a horse carried, resulting in a heavier, more powerful type of horse. </p>
<p>This marker is found at high frequency in the Australian racehorse population, indicating that Australian breeders have been unknowingly selectively breeding for this marker for many years by preferring strong powerful sprinting types of horse over lean staying types. </p>
<p>So is this the future of racehorse breeding? DNA testing is just one of many tools that breeders can apply in pursuit of that dream of producing an elite racehorse. Intangible skills such as evaluating a horse by eye will never be completely replaced by science. </p>
<p>Rags-to-riches tales such as the stories of <a href="http://www.dailytelegraph.com.au/sport/superracing/cabbie-joe-janiak-never-envisaged-he-would-travel-the-world-when-he-paid-1375-for-takeover-target/story-fni2gg7e-1226663469388?nk=cf698d0cb42a08fc83d538af0b18f93f">Joe Janiak and Takeover Target</a>, or <a href="http://www.heraldsun.com.au/sport/superracing/cox-plate-2014-mick-burles-warhorse-the-cleaner-holds-his-own-against-the-equine-elite/story-fnibcgg5-1227102239149">Mick Burles and The Cleaner</a>, will always be a part of Australian racing folklore, and there is no doubt our racing traditions are richer for them.</p><img src="https://counter.theconversation.com/content/33297/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natasha Hamilton is affiliated with RacingNSW on a casual basis.</span></em></p>The win of Japanese stayer Admire Rakti in the Caulfield Cup, followed by Irish bred colt Adelaide’s win in the Cox Plate last Saturday, has brought into question the stamina (staying) credentials of Australian…Natasha Hamilton, Lecturer in Veterinary Physiology, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/257532014-06-22T20:28:25Z2014-06-22T20:28:25ZGM techniques: from the field to the laboratory (and back again)<figure><img src="https://images.theconversation.com/files/51258/original/xjfm6mvm-1402969650.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Laboratory-based genetic modification is relatively new when you consider the centuries of selective breeding that precedes it.</span> <span class="attribution"><a class="source" href="http://www.flickr.com/photos/ricephotos/8364141562">IRRI Photos/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><em>Welcome to <a href="https://theconversation.com/topics/gm-in-australia">GM in Australia</a>, a series looking at the facts, ethics, regulations and research into genetically modified crops. In this first instalment, Peter Langridge describes two GM techniques: selective breeding and genetic engineering.</em></p>
<hr>
<p>Genetic modification (GM) sounds very laboratory-based – people in white coats inserting and deleting <a href="https://theconversation.com/explainer-what-is-a-gene-12951">genes</a> – but the vast majority of GM work was completed in the field through selective breeding.</p>
<p>Early Middle Eastern farmers collected grain from natural grasslands, but they needed to time their harvest very carefully. If they were too early the grain wouldn’t store well, and if they were too late the grain would spread over the ground making collection difficult.</p>
<p>At some stage, one of these early farmers must have noticed that some heads remained fixed on their stems even after the grain was fully dry. He obviously didn’t understand this at the time, but these were plants with a mutation in the genes controlling seed dispersal.</p>
<p>Farmers began preferentially choosing plants with this useful mutation and planting them, perhaps the first case of breeding and selecting for a novel trait.</p>
<h2>Exploiting genetic variation</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=759&fit=crop&dpr=1 600w, https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=759&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=759&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=954&fit=crop&dpr=1 754w, https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=954&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/51287/original/jdf5x58b-1402979267.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=954&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gregor Mendel.</span>
<span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Systematic breeding really began in the early 1900s when scientists rediscovered Silesian monk Gregor Mendel’s <a href="http://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593">groundbreaking work</a> on genetic inheritance in peas.</p>
<p>Breeding involves utilising genetic variation to produce new combinations of genes and gene variants. A breeder will cross two different lines and then select offspring that have improved performance.</p>
<p>Breeders are always looking for new sources of variation, normally from within the elite germplasm pool – that is, within established varieties. Many important traits, such as disease resistance, are controlled by single genes and can be crossed into elite lines, with only the resistant offspring selected.</p>
<p>But for many crops the level of diversity available within the elite germplasm pool is very narrow and breeders must look further afield for novel variation. This search led breeders to explore land races (varieties grown by traditional farmers) and even wild relatives (undomesticated progenitors of our modern crops). </p>
<p>In many cases crosses between the wild relatives and modern lines will not produce normal seeds, but the embryos can often be isolated from the developing seed and grown in sterile tissue culture to produce viable, fertile plants.</p>
<p>This technique, called <a href="http://naldc.nal.usda.gov/download/42085/PDF">embryo rescue</a>, has been widely used and many modern cultivars contain genes from wild relatives.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/51304/original/g3dq6f26-1402982029.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="http://www.flickr.com/photos/mr-morshee/4117842213">danbruell/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>The normal number of genes present in a crop plant is around 30,000 to 40,000 – the same as for humans. In making the crosses all 30,000 genes from the wild relative are introduced but the breeder may only want one gene.</p>
<p>The genes are linked along chromosomes with each chromosome carrying several thousand genes. The breeders need to break up the chromosomes from the wild relative into small fragments so that only the desired region is transferred – a process called chromosome engineering.</p>
<p>This can take several decades of work, making the use of wide crosses technically difficult and slow. Breeders want other methods of generating useful variation.</p>
<h2>Engineering mutations</h2>
<p>In the 1950s the idea of inducing mutations became an important technique for creating new variation. This involved using ionising radiation, such as X or gamma rays, or chemical mutagens.</p>
<p>These techniques produce random damage to the genetic information in the plant by changing the DNA directly or knocking out segments of the genome (the genetic make-up). Most mutations are deleterious, and the mutagenesis usually generates many thousands of unwanted changes, so the clean-up can be slow. </p>
<p>After exposing the plants to the mutagen, the breeders need to select for the beneficial mutations and remove the deleterious mutations.</p>
<p>Scientifically the ideal solution would be to be able to take a gene from any source and introduce it into your crop plant to change the plant’s characteristics. This would allow breeders to use variation from diverse sources and make changes just one gene at a time without the extensive collateral damage done by mutagenesis or wide crosses. This is what genetic engineering offers.</p>
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<h2>Enter the lab coats …</h2>
<p>The first genetically engineered crops <a href="http://www.pnas.org/content/80/15/4803.short">were produced in the 1980s</a> and, as in all areas of science, the technology continues to advance. The most widely used method today takes advantage of a natural DNA transfer mechanism.</p>
<p>Several groups of soil bacteria are able to engineer plants for their own benefit. These bacteria transfer a segment of their genome into the plant’s genome so that the transformed plant cells will proliferate and produce compounds that only the bacteria can use. In this way the bacteria control the plant development to produce nutrients for the bacteria.</p>
<p>The mechanisms for this type of natural genetic engineering are now well understood, allowing scientists to change the DNA segment transferred so that the genes causing altered plant growth are removed and new genes inserted.</p>
<p>How does this work practically? In a laboratory the scientist will design and build a DNA sequence containing specific sequences that delineate the region of DNA to be transferred (the left and right borders). They then insert the gene of interest and usually a selectable marker, such as resistance to a herbicide. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=760&fit=crop&dpr=1 600w, https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=760&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=760&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=956&fit=crop&dpr=1 754w, https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=956&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/51308/original/dnf5zbwj-1402982216.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=956&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Agrobacterium tumefaciens</em> attaching to a plant cell.</span>
<span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>This construct is then introduced into a bacteria called <a href="http://www.nepadbiosafety.net/subjects/biotechnology/plant-transformation-agro"><em>Agrobacterium tumefaciens</em></a>, which readily takes up DNA. The bacteria are then applied to growing plant tissues in sterile culture.</p>
<p>After a period the bacteria are removed and the plant tissues placed onto media containing the herbicide. Only the plant cells that have been transformed (those that took up the construct from the bacterium) are able to grow and divide.</p>
<p>These cells are allowed to multiply and divide until they produce plants, which are taken out of sterile culture to a glasshouse where they can grow to maturity. The genes that have been transferred will now be included in the genetic make-up of the plant.</p>
<p>Different species and even varieties will differ in their ability to take up DNA from the bacterium and to regenerate normal plants. Where in the genome the new DNA inserts is usually random but will preferentially occur in regions containing active genes.</p>
<p>Extensive growth trials and evaluation are needed to ensure that the transgenic or genetically engineered plant behaves as expected.</p>
<h2>… and back to the field</h2>
<p>In Australia all aspects of genetic engineering research are closely regulated. The researcher, organisation and facilities used must all be licensed and meet tight standards.</p>
<p>Before a field trial can be grown, the Office of the Gene Technology Regulator (<a href="http://www.ogtr.gov.au/">OGTR</a>) conducts a detailed risk assessment of the genes used, the reasons for the trial, and the design and management of the trial site. </p>
<p>The OGTR have issued 103 licenses for field trials covering 14 different crops. In Australia 37 genetically engineered crops have been approved for commercial cultivation for seven different species, but only GM cotton (eight different events) and canola (three events) are grown to any great extent.</p>
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<a href="https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/51311/original/ps88t452-1402982616.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><a class="source" href="http://www.flickr.com/photos/basf/4837267013/in/photolist-gBsi5y-gBsMcB-gBthYi-gBtgT2-gBsifd-gBshWN-gBsLfY-gBsHL9-gBsHKB-gBtiaa-gBsLaX-gBsKDN-gBsK3N-gBsKpt-gBsbZC-gBseD5-gBteLr-gBsfQ3-gBsCeC-8nsfXp-gBsJUa-gBsdvU-gBsfkq-gBsESd-gBsbfS-gBtdDM-gBtdfa-gBtdo6-gBsDXB-gBsGBA-gBtdQt-gBsEr3-gBsdPQ-gBsC9B-gBt9L6-gBs8VG-gBsars-gBtbki-gBtam4-gBsCPL-gBsD6h-8Ze8pK-8Zhbbh-8ZhaYd-dQJkWp-5x5GGa-9sWJ3f-nxyYDp-9RPXGo-a86UDZ">BASF - The Chemical Company/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>The resistance to GM crops in many parts of the world has encouraged scientists to look for alternative techniques for making targeted changes to the genetic make-up of crops and other organisms. </p>
<p>For example, a new technique called “<a href="https://theconversation.com/explainer-what-is-genomic-editing-25072">genome editing</a>” allows us to make specific changes to native genes within the plant that are essentially identical to the changes induced by mutagenesis but at only one site rather than all over the genome. Mutagenesis is widely used and is not subject to regulation – will the same apply to genome editing?</p>
<p>There are other developments that are also challenging the community’s views on new technologies. How will people feel about GM crops where a native gene has been isolated, changed and re-inserted (a process known as <a href="http://www.ncbi.nlm.nih.gov/pubmed/24396278">cisgenics</a>)?</p>
<p>What about using GM rootstocks engineered for resistance to root diseases, but grafted with non-GM scion so that they produce non-GM apples or avocados?</p>
<p>These questions are now challenging the regulators since the first examples are starting to become available.</p>
<hr>
<p><em><strong>Further reading: <br>
<a href="https://theconversation.com/setting-the-standards-who-regulates-australian-gm-food-25533">Setting the standards: who regulates Australian GM food?</a><br>
<a href="https://theconversation.com/safety-first-assessing-the-health-risks-of-gm-foods-26099">Safety first – assessing the health risks of GM foods</a><br>
<a href="https://theconversation.com/because-we-can-does-it-mean-we-should-the-ethics-of-gm-foods-28141">Because we can, does it mean we should? The ethics of GM foods</a></strong></em></p><img src="https://counter.theconversation.com/content/25753/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Langridge receives research funding from Pioneer/Dupont, the Australian Research Council, the Grains Research and Development Corporation, the South Australian Government, Australia/India Strategic Research Fund and the US AID program . He provides advice to several public sector research organisation in Europe, North America and to international agricultural aid programs.</span></em></p>Welcome to GM in Australia, a series looking at the facts, ethics, regulations and research into genetically modified crops. In this first instalment, Peter Langridge describes two GM techniques: selective…Peter Langridge, CEO, Australian Centre for Plant Functional GenomicsLicensed as Creative Commons – attribution, no derivatives.