Genome-wide identification of the HD-Zip gene family and functional characterization of VviHDZ03 related to bud dormancy in grapevine

• In total, 36 HD-Zip genes were identified in grapevine. • VviHDZ03 was identified as a key transcription factor in dormancy release of grapevine. • Overexpression of VviHDZ03 inhibited flowering and seed germination in tobacco. Bud dormancy is a crucial developmental process in grapevine ( Vitis vinifera L.), where the transition from bud dormancy to bud break directly affects the timing and quality of flowering and fruit maturation. The homeodomain leucine zipper (HD-ZIP, HDZ) family is known for its significant role in regulating plant development; however, its specific involvement in grapevine dormancy remains poorly understood. In this study, we identified 36 VviHDZ genes in the newly assembled T2T grapevine genome and conducted a comprehensive bioinformatic analysis of the HDZ family. We also examined the spatiotemporal expression patterns of VviHDZ genes across 54 grapevine tissues and 6 stages of bud dormancy. Differential gene expression was validated by qRT-PCR, which revealed that VviHDZ03 was highly expressed during the bud break stage. Furthermore, the overexpression of VviHDZ03 in tobacco demonstrated its growth-inhibitory function, with delayed seed germination in overexpression lines, suggesting its significant role in grapevine dormancy. This study provides an in-depth characterization of the HDZ family in grapevine, highlighting the pivotal role of VviHDZ03 in bud dormancy release and offering valuable insights for future functional studies on grapevine bud dormancy.