Cloning of a vacuolar H+-pryophosphatase gene from emphemeral plant Olimarabidopsis pumila whose overexpression improve salt tolerance in tobacco

Abstract

Olimarabidopsis pumila is a close relative of the model plant Arabidopsis thaliana but, unlike A.thaliana, it is a salt-tolerant ephemeral plant that is widely distributed in semi-arid and semi-salinized regions of the Xinjiang region of China, thus providing an ideal candidate plant system for salt tolerance gene mining. The vacuolar H⁺-translocating inorganic pyrophosphatase (V-H⁺-PPase) is an electrogenic proton pump that play pivotal role in translocating protons into vacuoles in plant cells. A V-H⁺-PPase gene, OpVP, was isolated from O. pumila in this study. The OpVP cDNA has an open reading frame of 2 313 bp, encoding a polypeptide of 770 amino acid residues with an estimated molecular mass of 80.7 kDa. The OpVP shows high amino acid similarity with other Brassicaceae V-H⁺-PPase genes. Expression profiles under salt and drought treatment, abcisic acid (ABA), indole-3-aceticacid (IAA) and gibberellins (GA) induction were investigated, and the results reveal that the expression of OpVP was induced in leaves under treatment with salt, drought, ABA, IAA and GA3. Overexpression of the OpVP gene confers enhanced salt tolerance to the transformed tobacco. Transgenic tobacco grows well in the presence of 200 mM NaCl, while wild-type plants exhibit chlorosis and growth inhibition, even death. Compared with wild-type, transgenic plants accumulated more Na⁺ in leaves. Moreover, the leaves of transgenic plants retain higher chlorophyll content during salt stress. This study shows that OpVP is a potential gene for salt tolerance, and can be used in future for developing salt tolerant crops.

Key words: H⁺-pyrophoshatase, Olimarabidopsis pumila, salt, abiotic stress.