A Tunisian Wild Grape Leads to Metabolic Fingerprints of Salt Tolerance.

Soil salinity is progressively impacting agriculture, including viticulture. Identification of genetic factors rendering grapevine (Vitis vinifera L.) resilient that can be introgressed into commercial varieties is necessary for safeguarding viticulture against the consequences of global climate change. To gain insight into the physiological and metabolic responses enabling salt tolerance, we compared a salt-tolerant accession of Vitis sylvestris from Tunisia, 'Tebaba', with '1103 Paulsen' rootstock widely used in the Mediterranean. Salt stress was slowly increased, simulating the situation of an irrigated vineyard. We determined that 'Tebaba' does not sequester sodium in the root but can cope with salinity through robust redox homeostasis. This is linked with re-channelling of metabolic pathways towards antioxidants and compatible osmolytes, buffering photosynthesis, such that cell-wall breakdown can be avoided. We propose that salt tolerance of this wild grapevine cannot be attributed to a single genetic factor but emerges from favorable metabolic fluxes that are mutually supportive. We suggest that introgression of 'Tebaba' into commercial varieties is preferred over the use of 'Tebaba' as a rootstock for improving salt tolerance in grapevine.