Abstract:

To identify and isolate genes related to abiotic stress (salinity and drought) tolerance in grapevine, a candidate gene approach led to the isolation from Cabernet Sauvignon cultivar of a full-length cDNA of dehydrin gene. The latter, named VvDhn, which is highly and mainly induced in late embryogenesis in seeds, encodes for a protein of 124 amino acids with a predicted molecular mass of 13.3 kDa. Details of the physicochemical parameters and structural properties (molecular mass, secondary structure, conserved domains and motives, and putative posttranslational modification sites) of the encoded protein have also been elucidated. The expression study of VvDhn was carried out within plant organs and tissues as well as under drought and salt stresses. VvDhn was not detected in vegetative tissue, whereas it was only expressed during seed development (during late embryogenesis) at extremely high levels and was induced by salt and drought stresses as well as ABA application. Moreover, salt stress induced VvDhn expression in the tolerant variety (Razegui) but not the sensitive variety (Syrah), which did not display expression variation during stress; VvDhn expression level and salt-stress response depend on regulatory mechanisms that are efficient only in the tolerant variety. On the other hand, under drought stress VvDhn was induced in both tolerant and sensitive varieties, with higher levels in the tolerant variety. In addition, stress signal molecules such as ABA (applied alone or in combination with saccharose) induced VvDhn expression, even at low levels. Minimal knowledge about the role and functionality of this gene is necessary and constitutes a prerequisite for including VvDhn in grapevine abiotic stress tolerance improvement programs.

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