VvWRKY13 from Vitis vinifera negatively modulates salinity tolerance

Abstract

WRKY transcription factors participate in the salt stress responses of various plant species, but the underlying functional mechanisms are not well understood, particularly in grape. In this study, the role of VvWRKY13 in the salt stress response was characterized and the underlying physiological and molecular mechanisms were explored. The results show that VvWRKY13 expression was induced by salt stress, and the VvWRKY13 transcript level in the salt stress-sensitive cultivar was significantly higher than that in the resistant cultivars. Overexpression of VvWRKY13 in Arabidopsis significantly inhibited the growth of transgenic plants under salt stress, indicating that VvWRKY13 has a negative effect on the salt stress response. The photosynthetic rate, contents of proline and soluble sugars, activities of superoxide dismutase (SOD) and catalase (CAT), as well as transcriptional levels of proline and soluble sugar metabolic genes, such as P5CS1, SS1, SS2 and G6PDH, as well as SOD and CAT encoding genes CAT1, CAT2, and Cu/Zn-SOD, all decreased under salt stress, whereas hydrogen peroxide and oxygen-free radical contents increased in transgenic Arabidopsis plants compared with those of wild-type plants. VvWRKY13 suppressed upregulation of SnRK2.3, ABF1, ABF2, ABF3, RD29B, RD29A, and RAB18 induced by salt stress, but showed no significant effect on the transcript levels of SnRK2.2, SnRK2.6, or RD22, indicating that VvWRKY13 affects salt stress tolerance via a specific abscisic acid signaling pathway. VvWRKY13, isolated from grapevine, negatively regulate salt stress tolerance by depressing photosynthetic capacity, inhibiting salt-induced accumulation of osmolytes and up-regulation in antioxidant activity as well as expression of related genes. VvWRKY13 may affects salt stress tolerance by specific ABA signalling.