An OVATE family protein GmOFP8 increases drought tolerance and nodule formation in soybean

OVATE family proteins (OFPs) are key regulators involved in plant development and stress responses. However, their biological roles in soybean remain largely unclear. In this study, we identified GmOFP8, a member of OVATE family in soybean, which exhibits root-specific expression and is transcriptionally responsive to both brassinolide and drought stress. Overexpression of GmOFP8 increased drought tolerance and nodule numbers, whereas knockout of GmOFP8 resulted in reduced drought resistance and fewer nodules, indicating its positive role in regulating drought stress responses and nodulation. Protein-protein interaction analyses demonstrated that GmOFP8 physically interacted with the glycogen synthase kinase 3-like kinase, GmSK2, and this interaction promotes the nucleocytoplasmic shuttling of GmOFP8. Furthermore, overexpression of GmSK2 in soybean hairy roots suppressed both drought tolerance and nodulation. Based on these findings, we propose that GmSK2 plays a conserved role in mediating the phosphorylation status of GmOFP8, as observed in rice, thereby contributing to the regulation of drought tolerance and nodulation in soybean. These results provide valuable genetic resources for molecular breeding strategies aimed at improving stress resilience and nitrogen fixation capacity in soybean.