RNA-seq from different drought states of Vitis vinifera L.

Grapevine is one of the most important crop in the world. However, the effect of climatic change on Vitis vinifera L. could affect dramatically the productivity of vineyards, causing many economic and ecological damages. One of the most important factor is drought and water availability. The varietal sensitivity is more pronounced in commercial varieties like Merlot than local varieties like Callet. In order to better understand the adaptive differences between these two varieties we used the transcriptomic, metabolic and hormonal analyses, at three different levels of drought stress (mild, high and extreme), using Richter 110 as rootstock. The differential expression genes (DEG) analysis were performed using RNA-seq data for each condition in roots and leaves. DEG results showed that the response started in roots, expressing more DEGs at mild drought stress in the two varieties. However, more DEGs were found out in Merlot than Callet, showing a main response in Merlot to mild drought. Nevertheless, in high and extreme drought conditions, DEGs analysis in leaves shown a high increase of DEG in the two varieties, being more pronounced in Callet than Merlot, differencing the strategy of response among them. Hormonal and metabolic results displayed two different pathways in drought responses. While Merlot allocated more resources to maintain cellular turgor increasing sugar and alditol concentration into the cells, Callet produced more secondary metabolites like mono or sesqui-terpenes, helping the sugar transport to the fruit and increasing quality berry. Furthermore, a higher photosynthetic activity was found in Callet than Merlot, showing higher water used efficiency.