Addition of a wheat gene increases the blight resistance of American chestnut trees 23 December 2014, by Chris Samoray

Environmental Sciences Directorate. The level of gamma-tocopherol was the same as in non- transgenic Chinese chestnuts, which are commonly eaten around the world.

Chestnut blight, caused by Cryphonectria parasitica, a fungus accidently introduced from Asia in the late 1800s, has caused American chestnut populations to crash from stands making up around a quarter of forests in the eastern United States to a handful of large trees and patches of saplings scattered throughout the region.

"The resistance of American chestnut to the blight is extremely low," Tschaplinski said. "Virtually any adult tree will succumb to the fungus very quickly, and in as little as three days the fungus can girdle the stem of a test seedling."

Researchers at the Department of Energy's Oak Part of the reason the fungus is so virulent is Ridge National Laboratory, working collaboratively because it produces oxalate, which causes with scientists funded by The American Chestnut chestnut tissues to rot. The wheat gene (oxalate Foundation, have helped confirm that addition of a oxidase) that was introduced into American wheat gene increases the blight resistance of chestnut by the research team associated with New American chestnut trees. York chapter of The American Chestnut Foundation, breaks down oxalate, helping to limit The ORNL team, in collaboration with foundation the deadly effects caused by the fungus. researchers led by Dr. William Powell of the State University of New York, used gas chromatography- "If you can stop the microbe from accumulating mass spectrometry to analyze chestnuts from oxalate, you can definitely slow the disease transgenic American chestnut trees—trees that progression," Tschaplinski said. were transformed with a wheat gene to increase resistance to blight. Results also showed that the In addition to their forest dominance, American transgenic chestnuts had similar metabolite chestnuts were an important food source for forest concentrations to a panel of non-transgenic nuts, animals. Before planting any transgenic American suggesting that they are edible. chestnut trees in the wild, regulatory approval by the FDA and USDA Animal and Plant Health "We found that the wheat gene kept oxalic acid Inspection Service will likely require verification that (oxalate) concentration—a key fungal necrotic the seeds are safe to eat. agent—from accumulating, and the only substantial difference from non-resistant trees was a slightly ORNL's role was to validate the concentration of lower level of gamma-tocopherol, a form of vitamin oxalate in the plant tissues, and assess for the E," said Tim Tschaplinski of ORNL's Energy and production of any unexpected or unusual metabolites in the seeds relative to that observed in

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a panel of wild-type (nontransgenic) seeds.

"The ORNL analyses help provide evidence of improved disease resistance, as well as minimal impact of transgenesis on nut quality," Tschaplinski said, adding, "A lot of American chestnut lines, including both transgenic and nontransgenic lines, are being developed for improved resistance.

"We're helping identify which lines have, or which are likely to have, improved resistance, and the underlying biochemical mechanisms."

While chestnut hungry diners won't yet be standing knee deep in chestnut piles described in tales of old, the study is another step in reviving the forest's mighty giant.

Provided by Oak Ridge National Laboratory APA citation: Addition of a wheat gene increases the blight resistance of American chestnut trees (2014, December 23) retrieved 26 September 2021 from https://phys.org/news/2014-12-addition-wheat-gene- blight-resistance.html

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