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WASHINGTON — <\/span>Billions of American chestnut trees<\/a> once covered the eastern United States. They soared in height, producing so many nuts that sellers moved them by train car. Every Christmas, they’re called to mind by the holiday lyric \u201cchestnuts roasting on an open fire.\u201d<\/p>\n But by the 1950s, this venerable tree went functionally extinct, culled by a deadly airborne fungal blight and lethal root rot. A new study out Thursday in the journal Science provides hope for its revitalization, finding that the genetic testing of individual trees can reveal which are most likely to resist disease and grow tall, thus shortening how long it takes to plant the next, more robust, generation.<\/p>\n A smaller gap between generations means a faster path to lots of disease-resistant trees that will once again be able to compete for space in Eastern forests. The authors hope that can occur in the coming decades.<\/p>\n \u201cWhat\u2019s new here is the engine that we\u2019re creating for restoration,\u201d said Jared Westbrook, lead author and director of science at The American Chestnut Foundation, which wants to return the tree to its native range that once stretched from Maine to Mississippi.<\/p>\n The American chestnut, sometimes called the \u201credwood of the East,\u201d can grow quickly and reach more than 100 feet (30 meters), produce prodigious amounts of nutritious chestnuts and supply lumber favored for its straight grain and durability.<\/p>\n But it had little defense against foreign-introduced blight and root rot. Another type of chestnut, however, had evolved alongside those diseases. The Chinese chestnut had been introduced for its valuable nuts and it could resist diseases. But it isn\u2019t as tall or competitive in U.S. forests, nor has it served the same critical role supporting other species.<\/p>\n So, the authors want a tree with the characteristics of the American chestnut and the disease resistance of the Chinese chestnut.<\/p>\n That goal is not new \u2014 scientists have been reaching for it for decades and made some progress.<\/p>\n But it has been difficult because the American chestnut’s desirable traits are scattered across multiple spots along its genome, the DNA string that tells the tree how to develop and function.<\/p>\n \u201cIt\u2019s a very complex trait, and in that case, you can\u2019t just select on one thing because you\u2019ll select on linked things that are negative,\u201d said John Lovell, senior author and researcher at the HudsonAlpha Genome Sequencing Center.<\/p>\n Breed for disease resistance alone and the trees get shorter, less competitive.<\/p>\n To deal with this, the authors sequenced the genome of multiple types of chestnuts and found the many places that correlated with the desired traits. They can then use that information to breed trees that are more likely to have desirable traits while maintaining high amounts of American chestnut DNA \u2014 roughly 70% to 85%.<\/p>\n And genetic testing allows the process to move faster, revealing the best offspring years before their traits would be demonstrated by natural growth and encountering disease. The closer the gap between generations, the faster gains accumulate.<\/p>\n Steven Strauss, a professor of forest biotechnology at Oregon State University who wasn’t involved in the study, said the paper identified some promising genes. He wants scientists to be able to edit the genes<\/a> themselves, a possibly faster, more precise path to a better tree. In an accompanying commentary piece in Science, he says regulations can bog down these ideas for years.<\/p>\n \u201cPeople just won\u2019t consider biotech because it is on the other side of this social, legal barrier” and that’s shortsighted, he said.<\/p>\n For people who have closely studied the American chestnut, the work begs an almost existential question: How much can the American chestnut be changed and still be an American chestnut?<\/p>\n \u201cThe American chestnut has a unique evolutionary history, it has a specific place in the North American ecosystem,\u201d said Donald Edward Davis, author of the American chestnut, an environmental history. \u201cHaving that tree and no other trees would be sort of the gold standard.\u201d<\/p>\n He said the tree was a keystone species, useful to humans and vital to bigger populations of squirrels, chipmunks and black bears \u2014 hybrids might not be as majestic or effective. He was pleased that the authors included some surviving American chestnuts in their proposal, but favored an approach that relied on them more heavily.<\/p>\n \u201cNot that the hybrid approach is itself bad, it is just that why not try to get the wild American trees back in the forest, back in the ecosystem, and exhaust all possibilities from doing that before we move on to some of these other methods?\u201d he said.<\/p>\n Lovells said resurrecting the species requires introducing genetic diversity from outside the traditional pool of American chestnut trees. The study authors\u2019 goal is tall, resilient trees and they are optimistic. <\/p>\n \u201cI think if we only select American chestnut (tree genes), period, there\u2019s going to be too small of a pool and we\u2019re going to end up with a genetic bottleneck that will lead to extinction in the future,\u201d said Lovell.<\/p>\n ___<\/p>\n The Associated Press receives support from the Walton Family Foundation for coverage of water and environmental policy. The AP is solely responsible for all content. For all of AP\u2019s environmental coverage, visit https:\/\/apnews.com\/hub\/climate-and-environment<\/a><\/p>\n<\/div>\n