小麦蛋白激酶基因TaSnRK2.1介导植株抵御盐分胁迫功能研究

SnRK2 family protein kinases play an important role in regulating plant growth and development and plant resistance to abiotic stress by impacting on signal transduction. In this study, the wheat protein kinase gene TaSnRK2.1 was systematically charactreized focusing on its molecular property, expression patterns in response to salt stress, and its function in mediating plant resistance to salt stress. The results showed that TaSnRK2.1 cDNA has a 1029 bp of open reading frame that encodes a 342 aa polypeptide. The TaSnRK2.1 protein contains the Ser/Thr kinase catalytic domain (aa 62- aa 318) commonly situated in SnRK2 family proteins. At the nucleic acid level, TaSnRK2.1 is highly similar to its homologous genes in species of Polish wheat, Thinopyrum, and barley. Under salt stress treatment, the expression levels of TaSnRK2.1 in both roots and leaves were shown to be in an induction pattern. Compared with wild-type (WT), the tobacco lines with TaSnRK2.1 overexpression exhibited improved growth traits under salt stress treatment, showing increased dry weight, fresh weight, and leaf area per plant, promoted stomatal closure rate, elevated contents of osmolytes and photosynthetic function, such as increased chlorophyll content (SPAD value), photosynthetic rate (Pn), and stomatal conductance (Gs), and decreased intercellular CO2 concentration. In addition, the TaSnRK2.1 overexpressing lines also showed higher activities of cell protective enzymes (SOD, CAT and POD) and lower content of membrane lipid peroxidation product (MDA) than WT plants. In contrast, the tobacco lines with knockdown expression of TaSnRK2.1 displayed alleviated growth property relative to WT under salt treatment, displaying decreased dry weight, slowed stomatal closure rate, lowered osmolytes contents, and decreased photosynthetic function and cytoprotective enzyme activities. Our investigation suggest that TaSnRK2.1 positively regulates plant salt stress tolerance through improving plant growth, osmolyte accumulation, plant photosynthetic function, antioxidant enzyme activity, and stomata movement upon salt signaling.