Abstract
BackgroundThe Na+/Ca2+ Exchanger (NCX) protein family is a member of the Cation/Ca2+ exchanger superfamily and its members play important roles in cellular Ca2+ homeostasis. While the functions of NCX family of proteins is well understood in humans, not much is known about the total complement of Na+/Ca2+ exchangers in plants and their role in various physiological and developmental processes. In the present study, we have identified all the NCX proteins encoded in the genomes of rice and Arabidopsis and studied their phylogeny, domain architecture and expression profiles across different tissues, at various developmental stages and under stress conditions.ResultsThrough whole genome investigation, we identified twenty-two NCX proteins encoded by fifteen genes in rice and sixteen NCX proteins encoded by thirteen genes in Arabidopsis. Based on phylogenetic reconstruction, these could be classified into five clades, members of most of which were found to possess distinct domain architecture. Expression profiling of the identified NCX genes using publicly available MPSS and microarray data showed differential expression patterns under abiotic stresses, and at various development stages. In rice, OsNCX1, OsNCX8, OsNCX9 and OsNCX15 were found to be highly expressed in all the plant parts and various developmental stages. qRT-PCR based expression analysis revealed that OsNCX3, OsNCX10 and OsNCX15 were highly induced by salt and dehydration stress. Besides, expression profiling showed differential regulation of rice NCX genes in response to calcium and EGTA. Interestingly, expression of none of the NCX genes was found to be co-regulated by NaCl and calcium.ConclusionsTogether, our results present insights into the potential role of NCX family of proteins in abiotic stresses and development. Findings of the present investigation should serve as a starting point for future studies aiming functional characterization of plant NCX family proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0054-5) contains supplementary material, which is available to authorized users.
Highlights
The Na+/Ca2+ Exchanger (NCX) protein family is a member of the Cation/Ca2+ exchanger superfamily and its members play important roles in cellular Ca2+ homeostasis
Identification and nomenclature of NCX proteins in Arabidopsis and rice genomes Genes encoding NCX proteins were identified in Arabidopsis (TAIR version 10) and rice (TIGR version 7) genomes by employing hidden markov model (HMM) (Hidden Markov Model) profile retrieved from Pfam database, keyword search and domain search functions
Our analysis has identified thirteen distinct chromosomal loci encoding for sixteen NCX proteins in Arabidopsis and fifteen chromosomal loci encoding for twenty-two NCX proteins in rice; and are reported to undergo alternative splicing
Summary
The Na+/Ca2+ Exchanger (NCX) protein family is a member of the Cation/Ca2+ exchanger superfamily and its members play important roles in cellular Ca2+ homeostasis. While the functions of NCX family of proteins is well understood in humans, not much is known about the total complement of Na+/Ca2+ exchangers in plants and their role in various physiological and developmental processes. Systemic and cellular homeostasis is very important for proper functioning of living organisms, including plants. The alkali (Na+, K+) and alkaline (Ca2+, Mg2+) earth metals play very critical roles in living system, but their optimum cellular concentration must be maintained for proper action (Jon et al 2008). As Ca2+ controls a number of physiological processes both at molecular and cellular levels in plants (Hepler and Wayne 1985), it is very crucial to regulate the Ca2+ level inside the cell
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