Comparative transcriptomic analysis of grapevine buds subjected to low temperature and short days revealed contrasting regulation of cell cycle genes in response to both environmental cues

Abstract

Abstract Background: With respect to grapevine buds, short days (SDs) induces endodormancy (ED), while low temperature (LT) induces cold hardiness. However, the relationship between both of these environmental cues has been explored little. In this study, transcriptomic data based on an RNA-sequencing (RNA-seq) analysis of grapevine buds exposed to LT and SDs were compared. Results: A total of 6121 differentially expressed genes (DEGs) were identified in the comparison between grapevine buds subjected to LT and control buds, while 1336 were identified in the comparison between grapevine buds subjected to SDs and long days (LDs). Cluster analysis showed that most gene differentially expressed in response to SDs were downregulated, while most genes differentially expressed in response to LT were upregulated. A small number of the DEGs were simultaneously upregulated or downregulated in response to LT and the SDs, while conversely, a large number of them were downregulated in response to SDs but upregulated in response to LT. Gen Ontology (GO) enrichment analysis of the DEGs downregulated in response to SDs and upregulated in response to LT indicated that most of these DEGs were related to the cell cycle. These results were somewhat surprising, since although cell cycle genes are downregulated during ED of grapevine buds as a consequence of SD conditions, their upregulation caused by LT was unexpected, since in other species, these genes are downregulated in response to LT. Conclusion: Repression of transcriptome and cell cycle genes in grapevine buds in response to SD, and massive upregulation of transcriptome and cell cycle genes in response to LT support the idea that SD induces the ED, and that the LT induces the release of the buds from the ED.