The scion-driven transcriptomic changes guide the resilience of grafted near-isohydric grapevines under water deficit

Abstract

[eng]The large diversity of grapevine cultivars englobes more tolerant genotypes to water deficit than others. Widely distributed cultivars, like Merlot, are more sensitive to water deprivation than some local cultivars like Callet, more adapted to water deficit by their Mediterranean origin. Despite their tolerance to water deficit, the adaptation to water deficit influenced by grafting in rootstocks like 110 Richter, is becoming key to face water deficit in vineyard defining the binomial scion/rootstock. To understand the different response among them, we explored these differences across transcriptomic, metabolic, hormonal and physiologic analysis at three different levels of water deficit (mild, high and extreme), using 110 Richter as rootstock in both cultivars. The results revealed the sensitivity to ABA as key for the water deficit tolerance in the aerial part, guiding the root response accordingly. In this response to ABA, Callet/110 Richter activates more gene expression patterns in response to that hormone, addressed to reduce water losses, compared to Merlot/110 Richter, in aerial and root parts. This modulation in Callet/110 Richter involves the regulation of metabolic pathways to increase cell turgor, the reduction of photosynthetic activity, and the production of molecules in response to oxidative stress, such as polyphenols or flavonoids. However, the unspecific of response to water deficit in Merlot/110 Richter in the aerial part and nearly absent in roots reveals a lack of cross talk and less resilience capacity to bad-watered conditions. Therefore, the selection of genotypes more ABA-sensitive and their communication with rootstocks is key to manage the vineyard for next scenarios caused by climate change.