The Transcriptome of Quiescence and Dormancy in Subtropical and Mediterranean Grapevine

Vine physiology is disorderly and requires intensive chemical and physical management, as the seasonal cues that grapevine relies on for developmental transitions are lacking. To gain insight into how differences in the temperature due to climate features can modify grapevine bud dormancy, a RNA-seq study was performed to investigate differences between subtropical and Mediterranean climates in table grapes (Flame Seedless).

For this, gene expression changes in buds from two adjacent vineyards in subtropical Western Australia (25°S latitude) were compared against one vineyard in a Mediterranean climate (32°S). Buds were collected at the end of summer and in mid-winter, over two successive years (2012 and 2013). Principal Components Analysis (PCA) revealed that the main factor explaining the global gene expression differences was the seasonality.

Differential expression analysis of subtropical and Mediterranean climates were performed (i) at the beginning and (ii) at the end of grape bud dormancy, and functional enrichments were carried. The first comparison showed a large difference between two consecutive seasons, while the second comparison showed major changes between climates. WRKY family transcription and oxidative stress (Glutathione S-transferase) categories sowed differences between climates at the beginning of dormancy. Whereas at the end was detected ethylene-mediated Signaling pathway and C2C2-YABBY family transcription factor categories.

This work provides a global view of major transcriptional changes taking place in Australian subtropical and Mediterranean climates, highlighting those molecular and biological functions that showed differences between climates, suggesting a main role of those functional categories during regulation of bud dormancy.