SHORT VEGETATIVE PHASE 3 mediates hormonal signals control of bud dormancy in grape

Bud dormancy is an essential and complex physiological process in perennial plants. Abscisic acid (ABA) is the major hormone regulating bud dormancy, however, the gene, SHORT VEGETATIVE PHASE (SVP) also plays a pivotal role. The combined regulation of SVP and ABA in the endodormancy network remains poorly characterized. In the present study, we demonstrate the growth inhibitory functions of VvSVP3 by its overexpressing it in tobacco and poplar. VvSVP3-overexpressing poplar plants prematurely stopped growing under short day, exhibiting delayed bud break in early spring. VvSVP3 regulates ABA, the gibberellic acid (GA) pathway, and the callose synthesis to promote dormancy within its network. In addition, exogenous application of ABA positively affects VvSVP3 expression. A transcriptomics and proteomics combined approach identified that VvPYL9 is a target gene of VvSVP3, which directly binds to a CArG motif in the VvPYL9 promoter to activate its expression. In summary, our results revealed the feedback regulation between VvSVP3 gene, ABA metabolism, and the dormancy signaling pathway in grape. It also provides new insights into the functional role of callose and ABA regulation in dormancy.