OsCYP71D10 Positively Regulates Rice Sheath Blight Resistance and is Associated with Altered Ascorbate-Related Metabolism and Redox Homeostasis

Abstract

Rice sheath blight, caused by the necrotrophic fungus Rhizoctonia solani , poses a major threat to global rice production. Breeding resistant varieties represents the most sustainable management strategy. Cytochrome P450 monooxygenases play diverse roles in plant defense metabolism, including phytoalexin biosynthesis and hormone metabolism. However, their potential involvement in ascorbate-associated resistance pathways remains largely unexplored, and no P450 enzyme has been reported to directly participate in ascorbate biosynthesis in plants. We functionally characterized the rice cytochrome P450 gene OsCYP71D10 through transgenic approaches. Overexpression of OsCYP71D10 in the susceptible variety Lemont significantly enhanced resistance to sheath blight, while RNA interference in the resistant variety Teqing compromised resistance. Integrated transcriptomic and metabolomic profiling of transgenic versus wild-type plants inoculated with R. solani AG1-IA revealed 2252 differentially expressed genes and 25 differentially accumulated metabolites. The “Ascorbate and aldarate metabolism” pathway was the only pathway significantly enriched at both transcriptional and metabolite levels. Notably, L-gulonic-γ-lactone (GulL), an intermediate in ascorbate biosynthesis, showed dramatic accumulation in overexpression lines, accompanied by increased ascorbic acid content and altered expression of redox-related genes ( OsGME1 , OsAPX , OsDHAR ). Exogenous application of GulL and ascorbic acid primed rice immunity against R. solani without direct fungicidal activity, inducing defense-related genes in jasmonic acid and salicylic acid signaling pathways.Our findings establish OsCYP71D10 as a positive regulator of rice sheath blight resistance. Integrated transcriptomic and metabolomic analyses suggest that OsCYP71D10 overexpression is associated with altered ascorbate-related metabolism, redox homeostasis, and defense hormone signaling. However, the direct biochemical function of OsCYP71D10 and its enzymatic substrate remain to be determined. This study provides a novel genetic resource for breeding sheath blight-resistant rice varieties and identifies a previously unrecognized connection between P450-mediated metabolism and ascorbate-related defense responses.