Enhanced Carbohydrate Metabolism and Salinity Tolerance of Tobacco Plants Overexpressing a Vacuolar H+-ATPase Subunit B2 (DoVHAb2) Gene from Yam (Dioscorea opposita Thunb.)

Abstract

ATP synthase plays a vital role in plant growth and stress tolerance, functional studies of DoVHAb2 in yam tuber starch metabolism and salinity tolerance have so far not been reported. Full-length cloning and analysis of DoVHAb2 were conducted to ascertain its function. The gDNAs were cloned and analyzed. Quantitative real-time polymerase chain reaction (qRT-PCR) was probed in yam tuber developmental stage and different organs of DoVHAb2. Transient expression vector was constructed and injected into tobacco leaves to observe the subcellular localization of genes. Overexpressed fusion vector of gene was constructed and transformed into tobacco by Agrobacterium-mediated method to identify the function of DoVHAb2 gene. In the results, the full-length of DoVHAb2 was 1926 bp, encoding 488 amino acids, and it was divided into 14 exons and 15 introns, its highest expression was found in tubers than in stems and leaves in yam, the yam DoVHAb2 protein was localized to cytoplasm. The starch content, ADP glucose pyrophosphorylase, starch synthase and ATPase activity were significantly higher in transgenic tobacco plants than in the wild-type. The transgenic plants also had higher leaf differentiation rate, soluble protein content, superoxide dismutase and peroxidase activities, and lower malondialdehyde content than the wild type under NaCl stress. In conclusion, the results indicated that overexpression of DoVHAb2 enhanced starch metabolism and conferred salinity tolerance.