Abstract
One of the main consequences of global warming in grapevine consists in the rise of berry K+ and sugar concentrations at harvest. This trend already observed since several decades in Europe (and further) results in wines with increasing alcohol contents, more flat, and with decreased ageing potential. The control of the sugar/acid balance of the berries would allow maintaining the typicity, the quality and the market value of French wines. This requires a better understanding of the molecular basis of K+ and sugar accumulations along grape berry development and in response to climate change. To this aim, the characterization of the molecular repertoire of genes and regulatory networks involved in the fine-tuning of the fruit sugar/acid balance at harvest was initiated using Cabernet Sauvignon fruiting cuttings. Differentially expressed genes from flesh cells upon drought and/or high temperature stress were identified through RNA-SEQ analysis. Here, we describe the functional characterization of a heat-inducible transcription factor belonging to the large ERF family (Ethylene Response Factor). VvERFhs is ubiquitously expressed in vine and highly inducible upon heat stress (HS). A RNA-SEQ analysis of transgenic grape cells overexpressing dominant and dominant-negative versions of VvERFhs was conducted. Several putative VvERFhs target genes linked to K+ or sugar accumulation were identified. Complementary approaches (Electrophoretic mobility shift assays, yeast-one-hybrid, and dual-luciferase assays) are on the way to evaluate the ability of VvERFhs to bind and transactivate the promoters of these different genes. In conclusion, the present work should contribute to open new research lines through the identification and characterization of key players involved in the control of berry quality and might provide an improved basis for the selection of vines better adapted to the ongoing climate change.