The bHLH transcription factor OsbHLH148 negatively regulates rice tiller number and grain yield through an integrated...

BACKGROUND: Rice is a staple food crop worldwide, and the number of tillers per plant is an important agronomic trait influencing grain yield. Consequently, investigating the molecular mechanisms regulating rice tillering is of great significance. RESULTS: This study systematically elucidated the biological function of the rice transcription factor OsbHLH148 in regulating tillering and yield formation. Through the generation of OsbHLH148-overexpressing transgenic lines, we observed a dwarf plant phenotype accompanied by a significant reduction in tiller number and a decrease of approximately 72% in grain yield per plant. OsbHLH148 protein was localized to both the cytoplasm and nucleus and exhibited a transcriptional activation activity. Integrated multi-omics analyses-including RNA sequencing (RNA-Seq), weighted gene co-expression network analysis (WGCNA), and DNA affinity purification sequencing (DAP-Seq), revealed that OsbHLH148 modulates a gene network associated with protein phosphorylation, Mitogen-activated protein kinase (MAPK) signaling, and secondary metabolite biosynthesis, thereby influencing tiller development. Furthermore, we identified and validated its direct target genes, such as MYB110, OsDREB1A, RLCK174, OsCIPK23, and MRLK26. CONCLUSIONS: These findings suggest that OsbHLH148 may inhibit rice tillering by regulating potential target genes involved in hormone signaling pathways (such as auxin and gibberellin), calcium signaling, and carbon and nitrogen metabolism. This study offers potential applications of these genes for improving rice yield and provides valuable genetic resources as well as a theoretical basis for molecular design breeding aimed at modifying plant architecture and enhancing productivity.