A BAHD acyltransferase STBR1 confers both saline-alkali tolerance and blast resistance by stabilizing the non-canonical catalase CATA to promote H2O2 scavenging in rice

Soil salinization and blast resistance are major constraints to global rice production. While plants maintain oxidative homeostasis to cope with such stresses, the key genetic components that integrate abiotic and biotic stress responses by modulating reactive oxygen species scavenging remain poorly understood. Here, we identify STBR1, a gene encoding a BAHD acyltransferase, as a critical regulator conferring dual tolerance to saline-alkali stress and blast resistance. Through association analysis and transgenic validation, we found that STBR1 overexpression enhances stress tolerance and grain yield. Mechanistically, we demonstrated via yeast two-hybrid, co-immunoprecipitation, and biochemical assays that the STBR1 protein physically interacts with and stabilizes the non-canonical catalase CATA, thereby promoting H₂O₂ scavenging and protecting cells from oxidative damage. Furthermore, we identified a natural elite haplotype, STBR1-T, which harbors a promoter mutation that attenuates binding by the transcriptional repressor NAC2 (verified by EMSA and ChIP-qPCR), leading to elevated STBR1 expression and superior stress resilience in rice. Our study elucidates the NAC2-STBR1-CATA module as a central hub coordinating oxidative homeostasis under combined abiotic and biotic stresses. The elite allele STBR1-T provides a direct and valuable genetic resource for breeding high-yielding rice cultivars with robust and broad-spectrum stress resistance.