Accumulating pesticide (and herbicide) residues in soils have become a serious environmental problem. This study focused on identifying the removal of two widely used pesticides, isoproturon (IPU) and acetochlor (ACT), by a genetically developed paddy (or rice) plant overexpressing an uncharacterized glycosyltransferase (IRGT1). IRGT1 conferred plant resistance to isoproturon–acetochlor, which was manifested by attenuated cellular injury and alleviated toxicity of rice under isoproturon–acetochlor stress. A short-term study showed that IRGT1-transformed lines removed 33.3–48.3% of isoproturon and 39.8–53.5% of acetochlor from the growth medium, with only 59.5–72.1 and 58.9–70.4% of the isoproturon and acetochlor remaining in the plants compared with the levels in untransformed rice. This phenotype was confirmed by IRGT1-expression in yeast (Pichia pastoris) which grew better and contained less isoproturon–acetochlor than the control cells. A long-term study showed that isoproturon–acetochlor concentrations at all developmental stages were significantly lower in the transformed rice, which contain only 59.3–69.2% (isoproturon) and 51.7–57.4% (acetochlor) of the levels in wild type. In contrast, UPLC-Q-TOF-MS/MS analysis revealed that more isoproturon–acetochlor metabolites were detected in the transformed rice. Sixteen metabolites of isoproturon and 19 metabolites of acetochlor were characterized in rice for Phase I reactions, and 9 isoproturon and 13 acetochlor conjugates were characterized for Phase II reactions in rice; of these, 7 isoproturon and 6 acetochlor metabolites and conjugates were reported in plants for the first time.

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Agricultural chemical residues in farmland and crops is one of the serious public issues that constantly threatens crop production, food security, and human health. Understanding their decay mechanism in crops for accelerating their degradative metabolism is important. In this study, a rice uncharacterized cytochrome P450 gene encoding CYP76C6 was functionally identified in rice exposed to isoproturon (IPU). To verify the role of CYP76C6 in rice resistance to IPU toxicity, CYP76C6 overexpression (OEs) and knockout mutant rice by CRISPR/Cas9 were generated through genetic transformation and gene-editing technologies. Assessment of growth and physiological responses revealed that the growth of OE lines was improved, the IPU-induced cellular damage was attenuated, and IPU accumulation was significantly repressed, whereas the Cas9 lines displayed a contrasting phenotype compared to the wild-type. Both relative contents of IPU metabolites and conjugates in OE lines were reduced and those in Cas9 line were increased, suggesting that CYP76C6 plays a critical role in IPU degradation. Our study unveils a new regulator, together with its mechanism for IPU decay in rice crops, which will be used in reality to reduce environmental risks in food safety and human health.