Exploiting somaclonal variability to increase drought stress tolerance in grapevine

Vitis vinifera is one of the most sensitive species to climate-change induced stresses, such as drought. Whether on one side it is crucial to understand how grape cultivars physiologically perceive and react to adverse climate conditions, on the other side it is necessary to improve existing breeding platforms using sustainable techniques allowing the selection of resilient genotypes. Somatic embryogenesis (SE) (i.e. the initiation of embryos from somatic tissues) represents a powerful green biotechnological tool for genetic improvement purposes. SE can spontaneously generate new genetic variability, called somaclonal variation, which results from genetic mutations, changes in epigenetic marks altering transposon activity and/or gene expression, or phenotypic alterations. This study was tailored to demonstrate whether vines in vitro regenerated through SE, namely somaclones, can endure water stress conditions better than the mother plant. A severe water deficit treatment was thereby imposed on a population of different somaclone lines of Vitis vinifera 'Nebbiolo' and on the corresponding mother plant line. During the trial, the main ecophysiological parameters (e.g. gas exchanges, relative water content, stem water potential) were monitored. Changes in biometric and anatomical traits were also inspected. Collected data allowed to identify those lines with improved tolerance to water stress. To deepen the mechanisms underlying the observed tolerance, biochemical and molecular analyses are ongoing to profile changes in the content of defense secondary metabolites and hormones and in the transcription of stress-responsive genes. In parallel, the genomes of the best and worst performing lines have also been sequenced.