Overexpression of the halophyte Kalidium foliatum H+-pyrophosphatase gene confers salt and drought tolerance in Arabidopsis thaliana

According to sequences of H+-pyrophosphatase genes from GenBank, a new H+-pyrophosphatase gene (KfVP1) from the halophyte Kalidium foliatum, a very salt-tolerant shrub that is highly succulent, was obtained by using reverse transcription PCR and rapid amplification of cDNA ends methods. The obtained KfVP1 cDNA contained a 2295 bp ORF and a 242 bp 3'-untranslated region. It encoded 764 amino acids with a calculated molecular mass of 79.78 kDa. The deduced amino acid sequence showed high identity to those of H+-PPase of some Chenopodiaceae plant species. Semi-quantitative PCR results revealed that transcription of KfVP1 in K. foliatum was induced by NaCl, ABA and PEG stress. Transgenic lines of A. thaliana with 35S::KfVP1 were generated. Three transgenic lines grew more vigorous than the wild type (ecotype Col-0) under salt and drought stress. Moreover, the transgenic plants accumulated more Na+ in the leaves compared to wild type plants. These results demonstrated that KfVP1 from K. foliatum may be a functional tonoplast H+-pyrophosphatase in contributing to salt and drought tolerance.