Molecular cloning and characterization of a new Na+/H+ antiporter gene from Brassica napus

A new Na+/H+ vacuolar antiporter gene from Brassica napus was cloned. The full-length cDNA of B. napus antiporter gene (BnNHX1, GenBank Acc. No. AY189676) was 1819 bp and contained a 1545 bp open reading frame encoding a protein of 515 amino acids. Homology analysis and molecular modeling revealed that BnNHX1 strongly resembled other Na+/H+ antiporter genes. Its encoded protein belonged to a typical sodium/hydrogen exchanger superfamily and shared consensus sequences within predicted transmemberane segments. Southern blot analysis indicated there were multi-copies of BnNHX1 gene present in B. napus genome, which was different from that in Oryza sativa previously reported. Northern blot analysis revealed that BnNHX1 was salt-inducible and its transcript level was most abundant after 24 h treatment with 200 mM sodium chloride. Our studies suggested that BnNHX1 was a new member of the family of recently cloned plant NHX-genes.