New physiological and genetic approaches to breed grapevines challenging climate warming
Résumé
Global warming already induced a drift towards earlier ripening, higher sugars and lower pH in grapevine. Resilient cultivars should be selected everywhere this metabolic syndrome is detrimental to wine quality. Two major innovations may help to elucidate the physiological and genetic bases of grapevine fruit response to warming: i) Reconsidering fruit ripening quantitative bases : RNA and metabolic profiles confirmed that berries at different stages coexist in clusters; circumventing artefacts of non‐synchronous samples elucidated water and osmoticum fluxes and their respective timings ; a H+/sucrose exchange, consistent with VVHT6 activation, is induced at the tonoplast; sugar accumulation continues after malate breakdown continues after malate breakdown completion without membrane energization; phloem loading stops around 26 days when sugar concentration continues by berry shriveling. ii) Microvine accelerates fruit genetics and breeding , due to the continuous production of reproductive organs and the lack of juvenile period. We have screened Vitis vinifera germplasm for fruit water and primary metabolite accumulation. Genotypes limiting sugars accumulation below 1 M at ripe stage were crossed to generate two microvine populations segregating for berry development and composition. GBS was performed to identify QTLs controlling fruit growth and primary metabolite accumulation, as new targets in breeding programs.