Genes contrastingly regulated by short days and low temperature are key players in the onset and cessation of endodormancy in grapevine buds

Abstract

Grapevine buds exhibit endodormancy (ED), triggered by short days (SD) and terminated through prolonged exposure to low temperature (LT). This study aims to unravel the genetic underpinnings the initiation and cessation of ED. Through previously reported SD-related gene expression changes and comparison with RNA-seq analysis of grapevine buds subjected to LT, we elucidated distinct gene clusters with contrasting regulation patterns. One cluster termed “Thermoregulatory Clock Cluster” encompassed 46 differential expressed genes (DEGs) upregulated by SD but downregulated under LT condition. Functional analysis revealed enrichment in circadian clock and temperature responsiveness functions. In contrast, the “Growth Control Cluster” comprising 292 DEGs downregulated under SD but upregulated under LT, is enriched in functions associated with cell division and transcription regulation. This investigation underscores the pivotal roles of genes associated with circadian clock, temperature responsiveness, cell division and transcriptional regulation in orchestrating the entry and exit of grapevine buds from ED. Furthermore, we propose a mechanistic model wherein LT-induced repression of circadian clock genes provokes the upregulation of SD-suppressed genes that promote ED. Thus, the role of LT in releasing buds from ED can be understood at the molecular level. This study not only advances our understanding of the genetic basis of bud ED, but also holds implications for viticulture and broader insights into plant dormancy regulation.