DkMYB117, a novel MYB transcription factor, regulates gibberellin catabolism to control plant height in persimmon interstock systems

Abstract

Dwarfing cultivation is a transformative strategy in modern fruit tree management, yet the molecular underpinnings of interstock-induced dwarfism remain elusive in persimmon (Diospyros kaki Thunb.). Here, we unveil DkMYB117, a novel R2R3-MYB transcription factor, as a key molecular switch orchestrating scion dwarfing via gibberellin (GA) catabolism. Using the dwarfing interstock ‘Nantongxiaofangshi’, we demonstrate that DkMYB117 expression is specifically suppressed in grafted scions, leading to reduced active GAs levels and stunted growth. Mechanistically, DkMYB117 directly binds to the MBSII element in the promoter of DkGA2ox2 to inhibit its expression. Conversely, the DELLA protein DkGAI2 interferes with the DNA-binding activity of DkMYB117 to DkGA2ox2, alleviating the transcriptional repression of DkGA2ox2. Overexpression of DkMYB117 elevates plant height via enhanced active GAs accumulation, while its silencing or DkGA2ox2 overexpression mimics the dwarf phenotype. Moreover, DkGAI2 mRNA is translocatable from interstock to scion, amplifying this dwarfing signal systemically. This study elucidates a DkMYB117-centered regulatory module that integrates interstock signals with GA metabolism to control plant height, providing insights and potential candidate genes for future breeding of dwarfed fruit trees.