Abstract

Dwarfism is an important agronomic trait in perennial fruit trees, although its molecular regulatory mechanism in persimmon remains poorly understood. In this study, we identified a bHLH transcription factor, DkLHW , which functions as a positive regulator of plant height in persimmon. Yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), and pull-down assays demonstrated that DkLHW interacts with DkMYB117. Electrophoretic mobility shift (EMSA) assays showed that DkLHW enhances the DNA-binding ability of DkMYB117 to the DkGA2ox2 promoter. Dual-luciferase reporter assays further demonstrated that this enhanced binding leads to stronger transcriptional repression of DkGA2ox2 . Heterologous overexpression of DkLHW in tobacco resulted in increased plant height, longer internodes, and elevated levels of active GAs. Similarly, transient overexpression of DkLHW in persimmon leaves down-regulated DkGA2ox2 expression and increased active GA content. Expression analysis showed that DkLHW transcript levels were significantly lower in the dwarf cultivar ‘Nantongxiaofangshi’ ( Diospyros kaki Linn.cv. Nantongxiaofangshi) compared with standard cultivars. These results indicate that DkLHW positively regulates persimmon plant height by forming a functional module with DkMYB117 to repress DkGA2ox2 expression and modulate gibberellin homeostasis. Our findings provide new insights into the transcriptional network controlling dwarfism in persimmon and identify DkLHW as a potential target for molecular breeding of plant architecture.