Investigation into the mechanism of VcHEC during blueberry bud dormancy release

• Blueberry bud dormancy release is mediated by VcHEC via auxin transport regulation. • VcHEC expression aligns with VcPIN3 during dormancy release. • Overexpression of VcHEC in arabidopsis accelerates seed germination. • VcSPL may repress VcHEC expression during dormancy. The HECATH ( HEC ) gene, a significant member of the basic helix-loop-helix (bHLH) transcription factor family, exerts a crucial influence on pistil development through the regulation of auxin and cytokinin biosynthesis and transport. The gene plays a pivotal role in the development of the pistil. To investigate the functional and regulatory roles of VcHEC in blueberry bud dormancy release, this study selected flower buds from the southern highbush blueberry cultivar 'O'Neal' (complex hybrids of V. corymbosum and low-chill Vaccinium species) as experimental materials. The research combined qRT-PCR analysis, genetic transformation techniques, and yeast one-hybrid assays to conduct systematic investigations. The results revealed significant differences in the VcHEC gene during the critical period of dormancy release, with its expression pattern aligning consistently with PIN-FORMED3 ( PIN3 ). Results further demonstrate that VcPIN3 is regulated by VcHEC , suggesting that the VcHEC gene may be involved in the release of blueberry bud dormancy by regulating the transport of auxin. The VcHEC gene enhanced the germination rate of Arabidopsis dormant seeds and facilitated plantlet development. Deletion of 5′ fragments gradually decreased promoter activity, with pro VcHEC showing much lower GUS staining intensity than p1 VcHEC (from -1,775 bp to -1 bp) and fluorescence analysis demonstrated this. Screening 12 upstream regulatory genes using the VcHEC promoter (from -2,272 bp to -1,775 bp) as bait identified a negative correlation between squamosa promoter-binding-like (SPL) and VcHEC expression based on transcriptome data. It is speculated that VcSPL may serve as a key repressor of VcHEC gene expression, warranting further investigation into the specific relationship. This study not only enriches our understanding of the biological function of the VcHEC gene but also provides a novel perspective on the study of dormancy release mechanisms. In summary, the research on the role of the VcHEC gene in blueberry bud dormancy release provides a theoretical basis for enhancing blueberry cultivation, breeding, and cold resistance management. It also broadens our understanding of the dormancy mechanisms in perennial woody plant species.