Shoot branching modulation by jasmonic acid through the QfMYC2/QfMYB111-QfBRC2 regulatory mechanism in Quercus fabri

Shoot branching plays a significant role in the phenotypic diversity and plasticity of plants, particularly in timber trees such as oaks. Jasmonic acid (JA) is recognized as essential for this process, however, the regulatory mechanisms of JA in the branching development of Quercus fabri remain unclear. In this study, we conducted a dynamic transcriptomic analysis on axillary bud development and identified two key regulatory genes, QfBRC2 and QfMYC2 , using weighted gene co-expression network analysis (WGCNA) and transcriptional regulation prediction analysis. Exogenous MeJA spraying experiments upregulated the expression levels of QfMYC2 and QfBRC2 while suppressing axillary bud development. Functional analysis revealed that QfMYC2 alone cannot activate the expression of QfBRC2 . It necessitates the formation of a functional complex with QfMYB111 to induce QfBRC2 expression. Simultaneous silencing of both QfMYC2 and QfMYB111 significantly reduced the expression level of QfBRC2 . Our findings indicate that JA regulates the expression of QfBRC2 through the QfMYC2-QfMYB111 module, thereby inhibiting axillary bud development. Overall, our findings reveal a novel model of phytohormone regulated branching JA-QfMYC2/QfMYB111-QfBRC2 and provide a new perspective on branch development research.