Deokar Amit A, Tar'an Bunyamin
Department of Plant Sciences, Crop Development Centre, University of Saskatchewan Saskatoon, SK, Canada.
Front Plant Sci. 2016 Nov 29;7:1802. doi: 10.3389/fpls.2016.01802. eCollection 2016.
Aquaporins (AQPs) are essential membrane proteins that play critical role in the transport of water and many other solutes across cell membranes. In this study, a comprehensive genome-wide analysis identified 40 AQP genes in chickpea ( L.). A complete overview of the chickpea AQP (CaAQP) gene family is presented, including their chromosomal locations, gene structure, phylogeny, gene duplication, conserved functional motifs, gene expression, and conserved promoter motifs. To understand AQP's evolution, a comparative analysis of chickpea AQPs with AQP orthologs from soybean, Medicago, common bean, and Arabidopsis was performed. The chickpea AQP genes were found on all of the chickpea chromosomes, except chromosome 7, with a maximum of six genes on chromosome 6, and a minimum of one gene on chromosome 5. Gene duplication analysis indicated that the expansion of chickpea AQP gene family might have been due to segmental and tandem duplications. CaAQPs were grouped into four subfamilies including 15 NOD26-like intrinsic proteins (NIPs), 13 tonoplast intrinsic proteins (TIPs), eight plasma membrane intrinsic proteins (PIPs), and four small basic intrinsic proteins (SIPs) based on sequence similarities and phylogenetic position. Gene structure analysis revealed a highly conserved exon-intron pattern within CaAQP subfamilies supporting the CaAQP family classification. Functional prediction based on conserved Ar/R selectivity filters, Froger's residues, and specificity-determining positions suggested wide differences in substrate specificity among the subfamilies of CaAQPs. Expression analysis of the AQP genes indicated that some of the genes are tissue-specific, whereas few other AQP genes showed differential expression in response to biotic and abiotic stresses. Promoter profiling of CaAQP genes for conserved -acting regulatory elements revealed enrichment of -elements involved in circadian control, light response, defense and stress responsiveness reflecting their varying pattern of gene expression and potential involvement in biotic and abiotic stress responses. The current study presents the first detailed genome-wide analysis of the AQP gene family in chickpea and provides valuable information for further functional analysis to infer the role of AQP in the adaptation of chickpea in diverse environmental conditions.
水通道蛋白（AQPs）是重要的膜蛋白，在水和许多其他溶质跨细胞膜运输中发挥关键作用。在本研究中，一项全面的全基因组分析在鹰嘴豆（Cicer arietinum L.）中鉴定出40个AQP基因。本文对鹰嘴豆AQP（CaAQP）基因家族进行了完整概述，包括它们的染色体定位、基因结构、系统发育、基因复制、保守功能基序、基因表达和保守启动子基序。为了解AQP的进化，对鹰嘴豆AQP与来自大豆、苜蓿、菜豆和拟南芥的AQP直系同源物进行了比较分析。鹰嘴豆AQP基因分布于除7号染色体外的所有鹰嘴豆染色体上，6号染色体上最多有6个基因，5号染色体上最少有1个基因。基因复制分析表明，鹰嘴豆AQP基因家族的扩张可能是由于片段重复和串联重复。基于序列相似性和系统发育位置，CaAQP被分为四个亚家族，包括15个NOD26样内在蛋白（NIPs）、13个液泡膜内在蛋白（TIPs）、8个质膜内在蛋白（PIPs）和4个小碱性内在蛋白（SIPs）。基因结构分析揭示了CaAQP亚家族内高度保守的外显子 - 内含子模式，支持了CaAQP家族分类。基于保守的Ar/R选择性过滤器、弗罗热残基和特异性决定位置的功能预测表明，CaAQP亚家族之间底物特异性存在广泛差异。AQP基因的表达分析表明，一些基因具有组织特异性，而其他一些AQP基因在生物和非生物胁迫下表现出差异表达。对CaAQP基因启动子进行保守顺式作用调控元件分析，发现参与昼夜节律控制、光响应、防御和胁迫反应的元件富集，这反映了它们不同的基因表达模式以及在生物和非生物胁迫反应中的潜在作用。本研究首次对鹰嘴豆AQP基因家族进行了详细的全基因组分析，并为进一步的功能分析提供了有价值的信息，以推断AQP在鹰嘴豆适应不同环境条件中的作用。
