Biodegradation of butachlor in rice intensified by a regulator of OsGT1

The constant utilization of herbicide butachlor to prevent weeds in agronomic management is leading to its growing accumulation in environment and adverse impact on crop production and food security. Some technologies proposed for butachlor degradation in waters and farmland soils are available, but the catabolic mechanism in crops polluted with butachlor remains unknown. How plants cope with the ecotoxicity of butachlor is not only a fundamental scientific question but is also of critical importance for safe crop production and human health. This study developed a genetically improved rice genotype by overexpressing a novel glycosyltransferase gene named OsGT1 to accelerate removal of butachlor residues in rice crop and its growth environment. Both transcriptional expression and protein activates of OsGT1 are considerably induced under butachlor stress. The growth of the OsGT1 overexpression rice (OsOE) was significantly improved and butachlor-induced cellular damage was greatly attenuated compared to its wild-type (WT). The butachlor concentrations in shoots and roots of the hydroponically grown OsOE plants were reduced by 14.1-30.7 % and 37.8-47.7 %. In particular, the concentrations in the grain of OsOE lines were reduced to 54.6-85.6 % of those in wild-type. Using LC-Q-TOF-HRMS/MS, twenty-three butachlor derivatives including 16 metabolites and 7 conjugations with metabolic pathways were characterized, and it turns out that the OsOE lines accumulated more degradative products than wild-type, implying that more butachlor molecules were intensively catabolized. Taken together, the reduced residues of parent butachlor in rice and its growth media point out that OsGT1 plays a critical role in detoxifying and catabolizing the poisoning chemical in plants and its environment.