Comparative Analysis of Cabernet Sauvignon (Vitis vinifera L.) and Kober 5BB (V. berlandieri × V. riparia) Root Transcriptomes Reveals Multiple Processes Associated with Drought Tolerance in Grapevines

Grapevine cultivars (Vitis vinifera L.) generally exhibit relatively high tolerance to drought stress. In contrast, the drought tolerance of other Vitis species and their hybrids used as rootstocks differs considerably. In order to attain a better understanding of the molecular basis of drought tolerance in grapevine, we conducted a comparative transcriptomic analysis of roots of drought-stressed Cabernet Sauvignon (CS, Vitis vinifera L.) and rootstock of Kober 5BB (V. berlandieri × V. riparia) using the Affymetrix Vitis Genome Array Version 2.0. We identified 1279 (745 upregulated and 534 downregulated) and 1925 (807 upregulated and 118 downregulated) differentially expressed genes in 5BB and CS. Numerous genes that are putatively involved in aquaporins, proline-rich protein, reactive oxygen species, osmoprotection, and lipid transfer were differentially expressed in response to drought stress in both genotypes. When gene ontology analyses were examined, it was observed that CS and 5BB genotypes were associated with the highest number of similar genes in both the molecular function (protein binding, catalytic activity, and DNA binding) and the biological process (metabolic process and translation) categories. The identification of different regulated genes between 5BB and CS roots is expected to help advance our understanding of molecular mechanisms operating during drought stress in grapevine roots.