Cloning and expression analysis of the B subuinit of V-H+-ATPase in leaves of halophyte Suaeda salsa under salt stress

For salinity stress tolerance in plants, the vacuolar type H+-ATPase (V-H+-ATPase) is of prime importance in establishing an electrochemical H+-gradient across tonoplast that energizes sodium sequestration into the central vacuole. In this paper, the sequence of a cDNA encoding the B subunit of the vacuolar-type H+-ATPase from Suaeda salsa L., a plant that can survive in seawater was reported. The B subunit cDNA is 1974 nucleotides long and include a 18 bp poly(A(+)) tail together with a complete 1470 bp coding region for a 489 amino acid with a conservative ATP binding site and a predicted molecular mass of 54.29 kD. Northern and Western blotting analyses indicated that the expression of B subunit was significantly up-regulated by NaCl treatment. Moreover, the expressions of B subunit were coordinated with c subunit of V-H+-ATPase at transcript and translation levels under NaCl stress. The increased V-H+-ATPase subunit amounts and activity of Suaeda salsa provide the energy for the compartmentation of sodium in response to salinity.