A stress associated protein from Chinese wild Vitis amurensis, VaSAP15, enhances the cold tolerance of transgenic grapes

Abstract

Stress associated protein (SAP) gene family can respond to a variety of biotic and abiotic stresses, and plays an important role in the process of improving the resistance of plants. In this study, we cloned a novel gene VaSAP15 from Chinese wild Vitis amurensis and validated its function in cold stress. Our data revealed that VaSAP15 protein localized in both nucleus and cell membrane. The SAP15 gene exhibited specific tissue expression in different grape genotypes, and strongly expressed in the roots of V. amurensis accession ‘Shuangyou’ (cold-tolerant) and in the stems of V. vinifera cultivar ‘Red Globe’ (cold-sensitive), respectively. Overexpressed VaSAP15 ‘Thompson Seedless’ (V. vinifera) lines were obtained by agrobacterium-mediated method. After cold stress at 0℃, the damage degree of transgenic line leaves was significantly lower than that of wild-type (WT), transgenic lines have the lower malondialdehyde (MDA) and electrolyte leakage (EL) and the higher activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Furthermore, the relative expression level of some cold-related genes including CBF1, CBF2, CBF3, COR27, RD29B and NCED1 were significantly up-regulated in transgenic lines. Besides, an interacting protein with VaSAP15, VaPDI1 (protein disulfide-isomerase), was screened out by yeast two-hybrid and verified by bimolecular fluorescence complementation assay. These results suggested that VaSAP15 may enhance grapevine cold tolerance through interacting with other proteins such as VaPDI1, which modulates signal transduction pathways and regulates the response of genes to environmental stresses in grapevine.