Identification and characterization of two genes encoding plasma membrane H + -ATPase in Cucumis sativus L.

Two genes ( CsHA2 , CsHA3 ) homolog to the plasma membrane H + -ATPase encoding sequences have been identified in cucumber cells. The full-length cDNA of these sequences comprise an open reading frame that encodes about 950 amino acid polypeptide with several potential transmembrane domains. Both sequences share a high homology with putative plasma membrane-associated proton pumps in higher plants, ranging from 84% with that of Arabidopsis thaliana to 90% with Sesbania rostrata . Phylogenetic analysis grouped the two isoforms into one group (subfamilies II) together with Kosteletzkya virginica KVATP1, Sesbania rostrata SRHA4 , tobacco PMA4 and rice OSA7. The expression of CsHA isoforms at the mRNA level showed they different organ pattern. Transcript level of CsHA2 was detected in all vegetative organs, but more abundantly in leaves than in roots, while CsHA3 expression was limited only to the roots in immature as well as in mature plants. Moreover, the RT-PCR analysis of generative organs (flowers), fruits and dry seeds revealed differential expression pattern for CsHA2 and CsHA3 suggesting that these proteins could be involved in separate physiological processes.