Grapevine TPS (trehalose-6-phosphate synthase) family genes are differentially regulated during development, upon sugar treatment and drought stress

Trehalose-6-phosphate synthase (TPS) performs the first step in the biosynthetic pathway of trehalose-6-phosphate and trehalose. These two molecules play key roles in the control of carbon allocation and of stress responses in plants. We investigated the organization of the TPS gene family and its developmental and environmental expression regulation in grapevine, a major horticultural crop. We identified three novel genes in the family, and assessed the expression of the 11 family members in tissues and developmental phases. Two potentially biosynthetic TPS isoforms belonging to Class I were preferentially expressed in leaf (VvTPS1_A) and in fruit (VvTPS1_B) respectively. Sucrose treatment induced expression of VvTPS1_B, but not of VvTPS1_A, and a progressive decrease of sucrose concentration. Expression of a few Class II genes was affected by sucrose treatment. Application of osmotic stress by withdrawing irrigation also induced a decrease in sucrose and an increase of glucose content, and down-regulation of the VvTPS1_A gene. We discuss the possible role of these potential biosynthetic TPS genes. Subgroups of TPS genes, including both Class I and ClassII isoforms, followed a co-expression pattern in different conditions, suggesting that Class II TPS proteins may directly or indirectly interact with TPS biosynthetic genes. Our results pave the way for clarification of the role of TPS isoforms in grapevine responses to environmental stress. •The grapevine TPS gene family was extended to 11 members.•The Class I VvTPS1_B is upregulated by sucrose and expressed in sink tissues.•A novel TPS Class I gene is highly expressed in leaf and is not sucrose-activated.•Expression of the leaf-specific VvTPSI_A is decreased by drought stress.•Drought stress induces lower expression of some Class II TPS genes.