Effect of herbicide safeners on glutathione concentrations in rice

• Cassidy Elton, Chemistry, Univeristy of Pittsburgh at Bradford

• Matt Limmer, Plant and Soil Chemistry, University of Delaware

The uptake of arsenic, a non-threshold carcinogen, in rice plants can negatively impact consumers worldwide. Increasing the crop’s glutathione levels can decrease the uptake of arsenic into the edible grain. Herbicide safeners can increase the plant’s glutathione production, which is the primary mechanism by which rice detoxifies arsenic. Arsenic complexed with glutathione in the roots is prevented from further translocation to the grain, thereby decreasing potential exposure. We determined how safeners affected glutathione levels in pure line rice plants using a hydroponic study. Rice was grown for 49 days in the greenhouse and exposed to 4 different safeners (fenclorim, dimepiperate, dichlormid, and isoxadifen-ethyl) at 40 µM for one week. Plants were flash frozen and analyzed for total glutathione and reduced glutathione colorimetrically. Safeners tended to increase overall glutathione levels and had contrasting effects on reduced glutathione levels in the shoots. The effect of the safeners on glutathione levels in the roots was safener-dependent. Further research is needed to identify optimal application method, timing, and concentration, as well as exploring different herbicide safeners in the effort to decrease rice grain accumulation of arsenic.