Modern Tomatoes Are Very Different From Their Wild Ancestors – and We Found Missing Links in Their Evolution
By Hamid Razifard and Ana Caicedo
The Big Idea: The tomato's path from wild plant to household staple is much more complex than researchers have long thought.
For many years, scientists believed that humans domesticated the tomato in two major phases. First, native people in South America cultivated blueberry-sized wild tomatoes about 7,000 years ago to breed a plant with a cherry-sized fruit. Later, people in Mesoamerica bred this intermediate group further to form the large cultivated tomatoes that we eat today.
But in a recent study, we show that the cherry-sized tomato likely originated in Ecuador around 80,000 years ago. No human groups were domesticating plants that long ago, so this implies that it started as a wild species, although people in Peru and Ecuador probably cultivated it later.
We also found that two subgroups from this intermediate group spread northward to Central America and Mexico, possibly as weedy companions to other crops. As this happened, their fruit traits changed radically. They came to look more like wild plants, with smaller fruits than their South American counterparts and higher levels of citric acid and beta carotene.
We were surprised to find that modern cultivated tomatoes seem most closely related to this wild-like tomato group, which is still found in Mexico, although farmers don't deliberately cultivate it.
Average fruit size in the cultivated tomato in comparison with its semi-domesticated and fully wild relatives. Hamid Razifard, CC BY-ND
Why it matters: This research has direct implications for crop improvement. For example, some intermediate tomato groups have high levels of glucose, which makes the fruit sweeter. Breeders could use those plants to make cultivated tomatoes more attractive to consumers.
We also saw signals that some varieties in this intermediate group had traits that promoted disease resistance and drought tolerance. Those plants could be used to breed hardier tomatoes.
What still isn't known: We don't know how the intermediate group of tomatoes spread from South America to Central America and Mexico. Birds may have eaten the fruits and excreted the seeds elsewhere, or humans may have cultivated or traded them.
Another question is why this intermediate group "regressed" and lost so many domestication traits once it spread north. Natural selection in new northern habitats may have actively favored tomatoes with more wild-like traits. It also could be that humans weren't breeding these plants and selecting for domestication traits, such as large fruits, which may require plants to use more energy than they would put into fruiting naturally.
How we do our work: We reconstruct tomato history by sequencing the genomes of wild, intermediate and domesticated tomato varieties. We also carry out population genomic analyses, in which we use models and statistics to deduce the changes that have occurred to tomatoes over time.
This work involves writing a lot of computer codes to analyze large amounts of data and look at patterns of variation in DNA sequences. We also work with other scientists to grow tomato samples and record data on many traits, such as fruit size, sugar content, acid content and flavor compounds.
What else is happening in the field: Feeding a growing human population will require improving crop yields and quality. To do this, scientists need to know more about plant genes that are involved in phenomena such as fruit development and flavor and disease resistance.
For example, research led by Zachary Lippman at the Cold Spring Harbor Laboratory in New York is using genome editing to manipulate traits that can help improve tomato yield. By tweaking genes native to two popular varieties of tomato plants, they have devised a rapid method to make the plants flower and produce ripe fruit more quickly. This means more plantings per growing season, which increases yield. It also means that the plant can be grown in latitudes more northerly than currently possible – an important attribute as the earth's climate warms.
What's next for you: Our research provides an atlas of candidates for future tomato gene function studies. We now can identify which genes were important at each stage of domestication history, and discover what they do. We also can search for beneficial alleles, or variants of specific genes, that may have been lost or diminished as the tomato was domesticated. We want to find out whether some of those lost variants could be used to improve growth and desirable traits in cultivated tomatoes.
Hamid Razifard is a postdoctoral researcher in biology at the University of Massachusetts Amherst.
Ana Caicedo is an associate professor of biology at the University of Massachusetts Amherst.
Disclosure statement: Hamid Razifard receives funding from National Science Foundation of USA. Ana Caicedo receives funding from the National Science Foundation (NSF) of the USA and the National Institute of Food and Agriculture (NIFA) of the USA.
Reposted with permission from The Conversation.
Many people shop online for everything from clothes to appliances. If they do not like the product, they simply return it. But there's an environmental cost to returns.
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EcoWatch Daily Newsletter
By Dolf Gielen and Morgan Bazilian
John Kerry helped bring the world into the Paris climate agreement and expanded America's reputation as a climate leader. That reputation is now in tatters, and President-elect Joe Biden is asking Kerry to rebuild it again – this time as U.S. climate envoy.
Energy Is at the Center of the Climate Challenge<p>The <a href="https://science2017.globalchange.gov/chapter/1/" target="_blank">effects of climate change</a> are already evident across the globe, from <a href="https://theconversation.com/100-degrees-in-siberia-5-ways-the-extreme-arctic-heat-wave-follows-a-disturbing-pattern-141442" target="_blank">extreme heat waves</a> to <a href="https://science2017.globalchange.gov/chapter/12/" target="_blank">sea level rise</a>. But while the challenge is daunting, there is hope. Solar and wind power have become the <a href="https://www.irena.org/publications/2020/Jun/Renewable-Power-Costs-in-2019" target="_blank">cheapest forms of power generation globally</a>, and technology progress and innovation continue apace to support a transition to clean energy.</p><p>In the U.S. under a Biden administration, long-term national climate legislation will depend on who controls the Senate, and that won't be clear until after two run-off elections in Georgia in January.</p><p>But there is no shortage of <a href="https://www.bloomberg.com/features/2020-biden-climate-change-advice/" target="_blank">ideas for ways Biden</a> could still take action even if his proposals are blocked in Congress. For example, he could use executive orders and direct government agencies to tighten regulations on greenhouse gas emissions; increase research and development in clean energy technologies; and empower states to exceed national standards, <a href="https://www.reuters.com/article/us-autos-emissions-california/defying-trump-california-locks-in-vehicle-emission-deals-with-major-automakers-idUSKCN25D2CH" target="_blank" rel="noopener noreferrer">as California did in the past with auto emission standards</a>. A focus on a just and equitable transition for communities and people affected by the decline of fossil fuels will also be key to creating a sustainable transition.</p><p>The U.S. position as the world's largest oil and gas producer and consumer creates political challenges for any administration. U.S. forays into European energy security are often treated with suspicion. Recently, France blocked <a href="https://www.wsj.com/articles/frances-engie-backs-out-of-u-s-lng-deal-11604435609" target="_blank">a multi-billion dollar contract</a> to buy U.S. liquefied natural gas because of concerns about limited emissions regulations in Texas.</p><p>Strengthening cooperation and partnerships with like-minded countries will be critical to bring about a transition to cleaner energy as well as sustainability in agriculture, forestry, water and other sectors of the global economy.</p>
Creating a Global Sustainable Transition<p>How the world recovers from COVID-19's economic damage could help drive a lasting shift in the global energy mix.</p><p>Nearly one-third of Europe's US$2 trillion economic relief package <a href="https://www.bloomberg.com/news/articles/2020-07-21/eu-approves-biggest-green-stimulus-in-history-with-572-billion-plan" target="_blank" rel="noopener noreferrer">involves investments that are also good for the climate</a>. The European Union is also strengthening its 2030 climate targets, though each country's energy and climate plans will be critical for successfully implementing them. The <a href="https://joebiden.com/clean-energy/" target="_blank" rel="noopener noreferrer">Biden plan</a> – including a $2 trillion commitment to developing sustainable energy and infrastructure – is aligned with a global energy transition, but its implementation is also uncertain.</p><p>Once Biden takes office, Kerry will be joining ongoing <a href="https://www.un.org/en/conferences/energy2021/about#:%7E:text=The%20overarching%20goal%20of%20the,2030%20Agenda%20for%20Sustainable%20Development.&text=Accelerate%20delivery%20of%20United%20Nations,related%20issues%20at%20all%20levels." target="_blank" rel="noopener noreferrer">high-level discussions on the energy transition</a> at the U.N. General Assembly and other gatherings of international leaders. With the U.S. no longer obstructing work on climate issues, the G-7 and G-20 have more potential for progress on energy and climate.</p><p>Lots of technical details still need to be worked out, including international trade frameworks and standards that can help countries lower greenhouse gas emissions enough to keep global warming in check. <a href="https://www.carbonpricingleadership.org/what" target="_blank" rel="noopener noreferrer">Carbon pricing</a> and <a href="https://www.csis.org/analysis/how-can-europe-get-carbon-border-adjustment-right" target="_blank" rel="noopener noreferrer">carbon border adjustment taxes</a>, which create incentive for companies to reduce emissions, may be part of it. A consistent and comprehensive set of national energy transition plans will also be needed.</p><p>The global shift to <a href="https://www.irena.org/publications/2019/Jan/A-New-World-The-Geopolitics-of-the-Energy-Transformation" target="_blank">clean energy will also have geopolitical implications for countries and regions</a>, and this will have a profound impact on wider international relations. Kerry, with his experience as secretary of state in the Obama administration, and Biden's plan to make the climate envoy position part of the National Security Council, may help mend these relations. In doing so, the U.S. may again join the wider community of countries willing to lead.</p>
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By Maria Caffrey
As we approach the holidays I, like most people, have been reflecting on everything 2020 has given us (or taken away) while starting to look ahead to 2021.
We Need More Than Listening<p>By now we have all become sadly accustomed to the current administration sidelining scientists, most prominently Dr. Anthony Fauci, because the facts they provide do not fit with the political rhetoric of the moment.</p><p>I have <a href="https://www.csldf.org/2019/08/22/csldf-helps-climate-scientist-maria-caffrey-fight-for-scientific-integrity/" target="_blank">my own history</a> of filing a scientific integrity complaint with the National Park Service (which falls under the Department of the Interior) after senior ranking employees attempted to censor one of my scientific reports. I know all too well the damage and pain that these actions cause, not just for the individual scientist, but also because these <a href="https://www.ucsusa.org/resources/attacks-on-science" target="_blank" rel="noopener noreferrer">attacks on science</a> over the last few years have undermined sound, evidence-based decision making.</p><p>President-elect Biden has repeatedly said that he will <a href="https://thehill.com/homenews/521638-trump-biden-will-listen-to-the-scientists-if-elected" target="_blank" rel="noopener noreferrer">listen to the scientists</a>. While this is certainly a welcome change, listening can only take us so far. This past week Lauren Kurtz from the <a href="https://www.csldf.org/" target="_blank" rel="noopener noreferrer">Climate Science Legal Defense Fund</a> and my colleague <a href="https://www.ucsusa.org/about/people/gretchen-goldman" target="_blank" rel="noopener noreferrer">Gretchen Goldman</a> published <a href="https://www.scientificamerican.com/article/ten-steps-that-can-restore-scientific-integrity-in-government/" target="_blank" rel="noopener noreferrer">an article</a> listing 10 actions the new administration should implement to show their commitment to strengthening government science:</p><ol><li>Clearly prohibit political interference and censorship.</li><li>Protect scientists' communication rights.</li><li>Acknowledge that attempts to violate scientific integrity, even if ultimately not fruitful, are still violations.</li><li>Protect federal scientists' right to provide information to Congress and other lawmakers.</li><li>Commit to incorporating the best science as part of agency decisions.</li><li>Elevate agency scientific integrity policies to have the full force of law.</li><li>Publicly release anonymized information about scientific integrity complaints and their resolutions at every agency.</li><li>Institute an intra-agency workforce, potentially under the White House <a href="https://www.ucsusa.org/sites/default/files/2020-09/strengthening-science-and-si-at-ostp.pdf" target="_blank" rel="noopener noreferrer">Office of Science and Technology Policy</a>, to coordinate scientific integrity efforts across agencies, foster discussion of policy improvements, and standardize criteria for policies across agencies.</li><li>Strengthen whistleblower protections.</li><li>Ensure that policies cover all actors who will be dealing with science.</li></ol>
Time for Action<p>I have spoken to many scientists, particularly federal scientists, who are eager to turn the page so they can hurry back to the work they had been doing before this administration, but I urge caution in assuming that things can be "normal" again.</p><p>Before Trump, I naively thought the scientific integrity policies established during the <a href="https://obamawhitehouse.archives.gov/blog/2016/12/19/scientific-integrity-policies-update" target="_blank">Obama administration</a> would be sufficient. I never imagined that any administration could so willfully ignore and attack expert advice and evidence that is intended to protect us and our public lands.</p><p>I have personally witnessed how hard our federal scientists work. They put in long hours with minimal pay (far less that what they could get if they worked in private industry) to pursue one simple goal: to make things better for the nation.</p><p>We need stronger scientific integrity policies to protect these people and their work. But more than that, we need stronger scientific integrity laws because they also benefit society.</p>
By Andrea Germanos
Environmental campaigners stressed the need for the incoming Biden White House to put in place permanent protections for Alaska's Bristol Bay after the Trump administration on Wednesday denied a permit for the proposed Pebble Mine that threatened "lasting harm to this phenomenally productive ecosystem" and death to the area's Indigenous culture.
<div id="da98c" class="rm-shortcode" data-rm-shortcode-id="478a197b7c59c92787c92bec92f1ac39"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1331662923710693376" data-partner="rebelmouse"><div style="margin:1em 0">Bristol Bay forever, Pebble mine never. #NoPebbleMine #SaveBristolBay https://t.co/CBQ9zuy8A5</div> — Save Bristol Bay (@Save Bristol Bay)<a href="https://twitter.com/SaveBristolBay/statuses/1331662923710693376">1606328156.0</a></blockquote></div>
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OlgaMiltsova / iStock / Getty Images Plus
By Gwen Ranniger
In the midst of a pandemic, sales of cleaning products have skyrocketed, and many feel a need to clean more often. Knowing what to look for when purchasing cleaning supplies can help prevent unwanted and dangerous toxics from entering your home.