A Rice P450 CYP709B2 Confers Dual Herbicide Resistance by Metabolic Detoxification

Excessive residues of herbicides isoproturon (IPU) and atrazine (ATZ) pose environmental and health risks. This study identifies the rice cytochrome P450 enzyme CYP709B2 as crucial for their detoxification and catabolism. CYP709B2 expression is specifically induced by IPU or ATZ exposure. Transgenic rice overexpressing CYP709B2 demonstrated significantly enhanced resistance to both herbicides, as evidenced by improved growth and reduced accumulation of IPU/ATZ in various tissues, including grains. In contrast, CRISPR/Cas9-generated CYP709B2 knockout mutants exhibited increased sensitivity and higher herbicide accumulation. Metabolomic profiling revealed decreased levels of IPU/ATZ in the OE lines, along with elevated levels of their metabolites and conjugates, indicating accelerated herbicide catabolism. Conversely, Cas9 lines exhibited an opposing metabolite profile. These findings identify CYP709B2 as a key enzyme driving the metabolic detoxification and degradation of IPU and ATZ in rice, presenting a potential genetic target for developing herbicide-resistant crops, thus addressing associated environmental and food safety risks.