New genetically engineered American chestnut will help restore the decimated, iconic tree

American chestnut trees were once among the most majestic hardwood trees in the eastern deciduous forests, many reaching 80 to 120 feet in height and eight feet or more in diameter. The species has a sad story to tell. Of the estimated four billion American chestnut trees that once grew from Maine to Georgia, only a remnant survive today.

The species was nearly wiped out by chestnut blight, a devastating disease caused by the exotic fungal pathogen Cryphonectria parasitica

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To restore this beloved tree, we will need every tool available. It’s taken 26 years of research involving a team of more than 100 university scientists and students here at the not-for-profit American Chestnut Research and Restoration Project, but we’ve finally developed a nonpatented, blight-resistant American chestnut tree.
One genetic tweak

My research partner, Dr. Chuck Maynard, and I work with a team at the SUNY College of Environmental Science and Forestry (ESF) that includes high school students, undergraduate and graduate students, postdoctoral fellows, colleagues from other institutions and volunteers. Our efforts focus on direct genetic modification, or genetic engineering, as a way to bring back the American chestnut.

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There is another logical question: what about unintended consequences? Of course undefined questions are impossible to answer, but logically the method producing the smallest changes to the plant should have the fewest unintended consequences. We have not observed nontarget transgene effects – that is, changes that we didn’t intend – on our trees or on other organisms that interact with our trees, for example with beneficial fungi.

And at any rate, unintended consequences aren’t constrained to the genetics lab. Chestnut growers have seen unintended consequences resulting from their hybrid breeding of chestnuts. One example is the internal kernel breakdown (IKB) seen in chestnut hybridization, caused by crossing a male sterile European/Japanese hybrid (“Colossal”) with Chinese chestnut. By mixing tens of thousands of genes with unknown interactions through traditional breeding, occasionally you get incompatible combinations or induced mutations that can lead to unintended outcomes like IKB or male sterility.

One of the key advantages of genetic engineering is that it’s far less disruptive to the original chestnut genome – and thus to its ecologically important characteristics. The trees remain more true to form with less chance of unforeseen and unwanted side effects. Once these genes are inserted, they become a normal part of the tree’s genome and are inherited just like any other gene. They have no more chance of moving to other species than do any of the approximately 40,000 genes already in chestnut.

More at: https://theconversation.com/new-genetically-engineered-american-chestnut-will-help-restore-the-decimated-iconic-tree-52191