Genomic Comparison of the P-ATPase Gene Family in Four Cotton Species and Their Expression Patterns in Gossypium hirsutum

Plant P-type H+-ATPase (P-ATPase) is a membrane protein existing in the plasma membrane that plays an important role in the transmembrane transport of plant cells. To understand the variety and quantity of P-ATPase proteins in different cotton species, we combined four databases from two diploid cotton species (Gossypium raimondii and G. arboreum) and two tetraploid cotton species (G. hirsutum and G. barbadense) to screen the P-ATPase gene family and resolved the evolutionary relationships between the former cotton species. We identified 53, 51, 99 and 98 P-ATPase genes from G. arboretum, G. raimondii, G. barbadense and G. hirsutum, respectively. The structural and phylogenetic analyses revealed that the gene structure was consistent between P-ATPase genes, with a close evolutionary relationship. The expression analysis of P-ATPase genes showed that many P-ATPase genes were highly expressed in various tissues and at different fiber developmental stages in G. hirsutum, suggesting that they have potential functions during growth and fiber development in cotton.