VaCPK21, a calcium-dependent protein kinase gene of wild grapevine Vitis amurensis Rupr., is involved in grape response to salt stress

Abstract

Ca2+-dependent protein kinases (CDPKs) are known to play important roles in signal transduction in response to various abiotic stresses that limit crop yields. Vitis amurensis is a wild grape species that possesses a high adaptive potential and displays a high resistance to environmental stresses, such as low temperatures or microbial pathogens. The roles of most grape CDPKs in the adaptation to various stresses have not yet been uncovered. A recent CDPK gene expression analysis revealed that expression of VaCPK21 gene was significantly up-regulated under salt stress and, to a less degree, under high mannitol and high temperature stresses in V. amurensis plant cuttings. In this study, the effects of overexpressing the VaCPK21 gene in callus cell lines of V. amurensis and transgenic plants of A. thaliana on their responses to abiotic stresses were investigated. The VaCPK21-overexpressing cell cultures of V. amurensis, soil-grown plants of A. thaliana, and seedlings of A. thaliana exhibited higher tolerance to salt stress in comparison with the controls transformed with the “empty” vector. Heat, cold, and drought stress resistance of the transgenic V. amurensis calli and A. thaliana plants was comparable to that of the controls. Under salt stress conditions, the stress-related genes AtCOR15, AtCOR47, AtCAT1, AtCSD1, AtNHX1, AtKIN1, AtRD26, and AtRD29B demonstrated strong up-regulation in the VaCPK21-transgenic but not in the control Arabidopsis plants. Together, the results indicate that VaCPK21 may act as a positive regulator involved in the grapevine response to salt stress.