Transcriptomic and biochemical investigations support the role of rootstock-scion interaction in grapevine berry quality

Background In viticulture, rootstock genotype plays a critical role to improve scion physiology, berry quality and to adapt grapevine (Vitis viniferaL.) to different environmental conditions. This study aimed at investigating the effect of two different rootstocks (1103 Paulsen - P - and Mgt 101-14 - M) in comparison with not grafted plants - NGC - on transcriptome (RNA-seq and small RNA-seq) and chemical composition of berry skin inPinot noir, and exploring the influence of rootstock-scion interaction on grape quality. Berry samples, collected at veraison and maturity, were investigated at transcriptional and biochemical levels to depict the impact of rootstock on berry maturation. Results RNA- and miRNA-seq analyses highlighted that, at veraison, the transcriptomes of the berry skin are extremely similar, while variations associated with the different rootstocks become evident at maturity, suggesting a greater diversification at transcriptional level towards the end of the ripening process. In the experimental design, resembling standard agronomic growth conditions, the vines grafted on the two different rootstocks do not show a high degree of diversity. In general, the few genes differentially expressed at veraison were linked to photosynthesis, putatively because of a ripening delay in not grafted vines, while at maturity the differentially expressed genes were mainly involved in the synthesis and transport of phenylpropanoids (e.g. flavonoids), cell wall loosening, and stress response. These results were supported by some differences in berry phenolic composition detected between grafted and not grafted plants, in particular in resveratrol derivatives accumulation. Conclusions Transcriptomic and biochemical data demonstrate a stronger impact of 1103 Paulsen rootstock than Mgt 101-14 or not grafted plants on ripening processes related to the secondary metabolite accumulations in berry skin tissue. Interestingly, theMYB14gene, involved in the feedback regulation of resveratrol biosynthesis was up-regulated in 1103 Paulsen thus supporting a putative greater accumulation of stilbenes in mature berries

The influence of grapevine rootstocks on scion growth and drought resistance

Grapes are a widely cultivated and economically important crop. Climate change is increasing the focus and investment on the development of more drought resistant varieties. However, markets often dictate specific grape varieties that can be grown and sold. Thus growers are increasingly interested in conferring particular traits of interest (e.g., drought tolerance) through grafting onto rootstocks. A major goal is to develop rootstocks that can influence scion growth and productivity under drought; particularly those that can increase water conservation through reducing the need for irrigation while ameliorating negative impacts on yields. Growers and scientists recognize that rootstocks have a profound influence on vine physiology (e.g., stomatal conductance, photosynthesis, water status), productivity (e.g., growth, fruit yields, fruit composition), and drought resistance. The challenge is to better understand the exact mechanisms through which rootstocks manifest these effects and thus build the knowledge necessary to drive the development of rootstocks with predictable effects on the scion. The aim of this review is to explore our current understanding of the mechanisms by which grapevine rootstocks influence scion growth and stress response; specifically focused on the integration of vine growth and productivity under water deficit