Overexpression of VaWRKY14 increases drought tolerance in Arabidopsis by modulating the expression of stress-related genes, including COR15A, COR15B, COR413, KIN2, and RD29A. The WRKY family is one of a largest transcription factors in plants, and it is a key component of multiple stress responses. In this study, the drought- and cold-induced WRKY family gene VaWRKY14 was isolated and characterized. Phylogenetic analysis indicated that VaWRKY14 belongs to the WRKY IIa subfamily, of which several members participate in biotic and abiotic stress responses in plants. Fluorescence observation from Arabidopsis mesophyll protoplasts transformed with the VaWRKY14::eGFP fusion vector suggested that VaWRKY14 was localized in the nucleus. The VaWRKY14 in yeast cells did not display any transcriptional activity. The expression of VaWRKY14 could be induced by exogenous phytohormones, including salicylic acid (SA) and abscisic acid (ABA). Overexpression of VaWRKY14 enhanced the drought tolerance of transgenic Arabidopsis. Compared with wild-type Arabidopsis, the VaWRKY14-OE lines exhibited higher water content and antioxidant enzyme activities in leaves after drought treatment. RNA sequencing analysis revealed that several stress-related genes, including COR15A, COR15B, COR413, KIN2, and RD29A, were upregulated in transgenic plants relative to their expression in wild-type Arabidopsis under normal conditions. Several genes (3 upregulated and 49 down-regulated) modulated by VaWRKY14 were also affected by drought stress in wild-type plants. These data suggest that VaWRKY14 responds to drought and cold stresses and that drought tolerance may be enhanced by regulating the expression of stress-related genes in Arabidopsis.
Keywords: Drought; Grapevine; Transcriptome; VaWRKY14; WRKY IIa.