Transcription Factor VvDREB2A from Vitis vinifera Improves Cold Tolerance

Low temperatures restrict the growth of the grapevine industry. The DREB transcription factors are involved in the abiotic stress response. Here, we isolated the VvDREB2A gene from Vitis vinifera cultivar 'Zuoyouhong' tissue culture seedlings. The full-length VvDREB2A cDNA was 1068 bp, encoding 355 amino acids, which contained an AP2 conserved domain belonging to the AP2 family. Using transient expression in leaves of tobacco, VvDREB2A was localized to the nucleus, and it potentiated transcriptional activity in yeasts. Expression analysis revealed that VvDREB2A was expressed in various grapevine tissues, with the highest expression in leaves. VvDREB2A was induced by cold and the stress-signaling molecules H2S, nitric oxide, and abscisic acid. Furthermore, VvDREB2A-overexpressing Arabidopsis was generated to analyze its function. Under cold stress, the Arabidopsis overexpressing lines exhibited better growth and higher survival rates than the wild type. The content of oxygen free radicals, hydrogen peroxide, and malondialdehyde decreased, and antioxidant enzyme activities were enhanced. The content of raffinose family oligosaccharides (RFO) also increased in the VvDREB2A-overexpressing lines. Moreover, the expression of cold stress-related genes (COR15A, COR27, COR6.6, and RD29A) was also enhanced. Taken together, as a transcription factor, VvDREB2A improves plants resistance to cold stress by scavenging reactive oxygen species, increasing the RFO amount, and inducing cold stress-related gene expression levels.