Mechanism Analysis of OsbHLH34-OsERF34 Mediated Regulation of Rice Resistance to Sheath Blight

Transcription factors are pivotal molecules involved in transcriptional and post-transcriptional regulation in plants, playing a crucial role in combating biological stress. Here, we have characterized a regulatory factor, OsbHLH34, which governs the response of rice to infection by Rhizoctonia solani AG1-IA. The expression of OsbHLH34 significantly impacts the susceptibility of rice to Rhizoctonia solani infection. Through the generation of OsbHLH34 knockout and overexpressing rice plants, we observed that OsbHLH34 acts as a positive regulator of rice resistance against rice sheath blight. The average lesion area of overexpression plants was 14.3%, the average lesion area of wildtype plants was 36%, and the average lesion area of mutant plants was 67.6%. Transcriptome and qRT-PCR analysis showed that OsbHLH34 regulates OsERF34, which is a key transcription factor for ethylene biosynthesis and resistance to sheath blight. By employing yeast one-hybrid and dual luciferase assays, we demonstrated that OsbHLH34 directly interacts with the promoter of OsERF34, thereby activating its transcription. Both in vitro and in vivo experiments confirmed OsERF34 as a direct target of OsbHLH34. These findings not only enhance our understanding of the molecular mechanisms underpinning rice disease resistance but also offer novel targets for the improvement of rice disease resistance through breeding strategies.