Cyclin C and EB1c cooperatively regulate plant height in eggplant via internode elongation.

Plant height is an important agronomic characteristic that influences crop productivity and overall plant structure. Elucidating the molecular mechanisms underlying stem elongation in eggplant (Solanum melongena L.) is essential for advancing crop improvement. In this study, we identified a semi-dwarf eggplant mutant, eggplant dwarf4 (edf4), generated through Ethyl methanesulfonate (EMS) mutagenesis. Genetic mapping and functional analyses revealed that a point mutation in SmCycC, which encodes a homolog of Cyclin C, is responsible for the dwarf phenotype. The edf4 mutant exhibited 28.67% (p < 0.01) reduced plant height and 21.35% (p < 0.01) shorter internodes, concomitant with suppressed cell proliferation. VIGS-mediated silencing of SmCycC recapitulated the dwarf phenotype, with plant height reduced by 26.3% (p < 0.05). This evidence confirms that SmCycC positively drives internode elongation and overall plant height by enhancing cell division. We further identified SmEB1c, a microtubule plus-end binding protein, as a physical interactor of SmCycC. Silencing SmEB1c leads to plant dwarfism caused by decreased cell number, supporting its role as a positive regulator of stem growth. Together, these findings uncover a SmCycC-SmEB1c regulatory module that controls plant height by affecting cell division in eggplant, providing promising genetic targets for breeding semi-dwarf cultivars.