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Palmer amaranth is a nightmare of a weed, causing yield losses up to 80 percent in severely infested soybean fields. It scoffs at farmers' attempts at control, having evolved resistance to six classes of herbicides since its discovery in the United States 100 years ago. And now, scientists have discovered it has two new tricks up its sleeve.
About a year ago, a group of researchers discovered Palmer is resistant to the herbicide class known as PPO-inhibitors, due to a mutation—known as the glycine 210 deletion—on the PPX2 gene.
Test - Waterhemp - PPO-resistance - Mutation - Lot
"We were using a quick test that we originally developed for waterhemp to determine PPO-resistance based on that mutation. A lot of times, the test worked. But people were bringing in samples that they were fairly confident were resistant, and the mutation wasn't showing up. We started to suspect there was another mechanism out there," says University of Illinois molecular weed scientist Patrick Tranel.
Tranel and his colleagues decided to sequence the PPX2 gene in plants from Tennessee and Arkansas to see if they could find additional mutations. Sure enough, they found not one, but two, located on the R98 region of the gene.
Plants - Glycine - Deletion - R98 - Mutations
"Almost all of the PPO-resistant plants we tested had either the glycine 210 deletion or one of the two new R98 mutations. None of the mutations were found in the sensitive plants we tested," Tranel says.
Furthermore, some of the...
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