Genome‐wide expressional and functional analysis of calcium transport elements during abiotic stress and development in rice

Ca 2+ homeostasis is required to maintain a delicate balance of cytosolic Ca 2+ during normal and adverse growth conditions. Various Ca 2+ transporters actively participate to maintain this delicate balance especially during abiotic stresses and developmental events in plants. In this study, we present a genome‐wide account, detailing expression profiles, subcellular localization and functional analysis of rice Ca 2+ transport elements. Exhaustive in silico data mining and analysis resulted in the identification of 81 Ca 2+ transport element genes, which belong to various groups such as Ca 2+ ‐ ATP ases (pumps), exchangers, channels, glutamate receptor homologs and annexins. Phylogenetic analysis revealed that different Ca 2+ transporters are evolutionarily conserved across different plant species. Comprehensive expression analysis by gene chip microarray and quantitative RT ‐ PCR revealed that a substantial proportion of Ca 2+ transporter genes were expressed differentially under abiotic stresses (salt, cold and drought) and reproductive developmental stages (panicle and seed) in rice. These findings suggest a possible role of rice Ca 2+ transporters in abiotic stress and development triggered signaling pathways. Subcellular localization of Ca 2+ transporters from different groups in Nicotiana   benthamiana revealed their variable localization to different compartments, which could be their possible sites of action. Complementation of Ca 2+ transport activity of K616 yeast mutant by Ca 2+ ‐ ATP ase Os ACA 7 and involvement in salt tolerance verified its functional behavior. This study will encourage detailed characterization of potential candidate Ca 2+ transporters for their functional role in planta .