The plasma membrane proton pump gene family in cucumber

Abstract

Plasma membrane H+-ATPase, which generates the proton gradient across the outer membrane of plant cells, plays a crucial role in the regulation of many physiological processes. In several species, PM H+-ATPase is encoded by a multigene family (HA). In contrast to Arabidopsis thaliana, Nicotiana plumbaginifolia and Oryza sativa, there is little information about the HA family in cucumber. Thus, in this study the first comprehensive analysis of the Cucumis sativus HA family was made. Using Blastn searches of cucumber whole genome shotgun reads from the GenBank database with 12 A. thaliana cDNAs encoding AtAHA1-12 proteins as the query, we retrieved a total of ten sequences, which significantly matched with AtAHAs. Phylogenetic analysis of CsHAs based on protein alignment revealed the representatives of three (I, II and IV) among five subfamilies known in other plant species. Expression patterns of genes showed their specific profiles during different phases of cucumber development and under specific exogenous factors. We also identified the putative cis-acting elements in CsHA promoters. Furthermore, the links between the patterns of cis-regulatory elements and tissue-specific or environmental-responding expression of genes as a first step to understanding the regulatory mechanism of HA in cucumber was performed. Our results provide a valuable basis for future studies aimed at explaining the role of particular H+-ATPase isoforms in cucumber responsiveness to the specific environmental factors.