Dual Regulatory Roles of SlGAMYB1 in Tomato Development: GA-Dependent and GA-Independent Mechanisms.

The R2R3-MYB transcription factor GAMYB plays crucial roles in plant growth and development, but the biological functions of in tomato remain poorly understood. Here, we investigated the roles of by overexpressing a miR159-resistant version () in tomato. Transgenic plants exhibited a dwarf phenotype with reduced internode elongation, which was associated with decreased bioactive gibberellin (GA) levels due to transcriptional repression of and activation of . Additionally, altered leaf morphology by inhibiting cell proliferation through downregulation of cell cycle genes, resulting in larger but fewer epidermal cells. Intriguingly, plants displayed increased floral organ number, a process likely mediated by the upregulation of rather than GA signaling. These findings demonstrate that regulates diverse aspects of tomato development through both GA-dependent and independent pathways, providing new insights into the functional diversification of genes and potential strategies for genetic improvement of tomato architecture and yield.