The MADS-box transcription factor VvSVP1 negatively regulates grapevine bud dormancy release

Abstract

Grape (Vitis vinifera L.), an economically important fruit tree grown worldwide, exhibits high sensitivity to environmental fluctuations during bud dormancy release. To address challenges such as warm winters and late-spring cold spells, and to elucidate the molecular mechanisms underlying grapevine bud dormancy release, this study investigated the regulatory role of the MADS-box transcription factor VvSVP1 in this process. Transient silencing of VvSVP1 promoted bud break in grapevine, whereas its overexpression delayed bud break, providing clear evidence that VvSVP1 has a negative regulatory role in bud dormancy release. Mechanistically, VvSVP1 interacted directly with the promoter regions of the abscisic acid (ABA)-catabolism gene VvCYP707A4 and the florigen gene VvFT, inhibiting their expression and impeding ABA degradation and meristem activation. In addition, transcriptome analysis indicated that silencing of VvSVP1 activated broader transcriptional programs related to phenylpropanoid metabolism, central carbon metabolism, and hypoxia response. Upstream of VvSVP1, the ABA-responsive element binding factor VvABF2 was identified as a positive regulator. Transient silencing of VvABF2 promoted dormant grapevine bud break and significantly reduced VvSVP1 expression, accompanied by up-regulation of VvCYP707A4 and VvFT. Together, these results support a regulatory model for grapevine bud dormancy release centered on VvSVP1. This work provides a theoretical basis for the screening of ecofriendly dormancy release agents and for studying the regulatory mechanisms involved in bud dormancy release of other fruit trees.