Genome-Wide Identification and Characterization of Banana Ca(2+)-ATPase Genes and Expression Analysis under Different Concentrations of Ca(2+) Treatments

Ca(2+)-ATPases have been confirmed to play very important roles in plant growth and development and in stress responses. However, studies on banana (Musa acuminata) Ca(2+)-ATPases are very limited. In this study, we identified 18 Ca(2+)-ATPase genes from banana, including 6 P-IIA or ER (Endoplasmic Reticulum) type Ca(2+)-ATPases (MaEACs) and 12 P-IIB or Auto-Inhibited Ca(2+)-ATPases (MaACAs). The MaEACs and MaACAs could be further classified into two and three subfamilies, respectively. This classification is well supported by their gene structures, which are encoded by protein motif distributions. The banana Ca(2+)-ATPases were all predicted to be plasma membrane-located. The promoter regions of banana Ca(2+)-ATPases contain many cis-acting elements and transcription factor binding sites (TFBS). A gene expression analysis showed that banana Ca(2+)-ATPases were differentially expressed in different organs. By investigating their expression patterns in banana roots under different concentrations of Ca(2+) treatments, we found that most banana Ca(2+)-ATPase members were highly expressed under 4 mM and 2 mM Ca(2+) treatments, but their expression decreased under 1 mM and 0 mM Ca(2+) treatments, suggesting that their downregulation might be closely related to reduced Ca accumulation and retarded growth under low Ca(2+) and Ca(2+) deficiency conditions. Our study will contribute to the understanding of the roles of Ca(2+)-ATPases in banana growth and Ca management.