Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, India.
Division of Plant Biochemistry, ICAR-Indian Institute of Pulses Research, Kanpur, India.
Physiol Plant. 2024 Sep-Oct;176(5):e14563. doi: 10.1111/ppl.14563.
In the current study, we have performed a comprehensive analysis of the Sodium Hydrogen Exchanger (NHX) gene family in Vigna mungo, and a total of 44 NHX genes were identified. A bimodal distribution based on domains, gene structure and phylogenetic analysis was evident. All intronpoor and intron-rich genes were clustered in clades I and II, respectively. Interestingly, all genes of subclade IIb were localized to vacuoles and possess only the NHX domain. The isoelectric point and trans-membrane domain analysis reflect the wide distribution of the NHX genes. Interestingly, Vm_NHX2 and Vm_NHX3 lacked trans-membrane domain but were found to interact with other NHX genes as well as vital salinity pathway genes, including calcium-mediated salt-responsive genes. The comparison of the mRNA sequences with that of V. marina, a halophytic species, reflects their independent evolution, majorly supporting the convergent evolution. The Ka/Ks ratio reflects the abundance of purifying selection supporting their conserved function during evolution. In our analysis, several abiotic stress and hormone-responsive elements and transcription factor binding sites were present in the promoter of the NHX genes. Further, the ion partitioning of a tolerant (K90) and a susceptible (K49) variety of V. mungo suggested that K90 managed the Na/K ratio more affluently, which was also supported by profiling of superoxide radicals, hydrogen peroxide, phenol, peroxidase activity and superoxide dismutase activity. From the expression, we identified five candidate Vm_NHX genes, four of which, i.e. Vm_NHX16, Vm_NHX17, Vm_NHX29 and Vm_NHX33, were localized to the vacuolar and lysosomal membrane.
在本研究中，我们对豇豆中的钠离子-氢逆向转运蛋白（NHX）基因家族进行了全面分析，共鉴定出 44 个 NHX 基因。基于结构域、基因结构和系统发育分析，发现存在双峰分布。所有内含子贫乏和内含子丰富的基因分别聚类在 I 类和 II 类中。有趣的是，所有亚类 IIb 的基因都定位于液泡中，并且只具有 NHX 结构域。等电点和跨膜结构域分析反映了 NHX 基因的广泛分布。有趣的是，Vm_NHX2 和 Vm_NHX3 缺乏跨膜结构域，但被发现与其他 NHX 基因以及重要的盐胁迫途径基因相互作用，包括钙介导的盐响应基因。与盐生植物 V. marina 的 mRNA 序列比较反映了它们的独立进化，主要支持趋同进化。Ka/Ks 比值反映了丰富的纯化选择，支持它们在进化过程中保守的功能。在我们的分析中，NHX 基因启动子中存在几种非生物胁迫和激素响应元件和转录因子结合位点。此外，耐盐（K90）和敏感（K49）品种豇豆的离子分配表明，K90 更有效地管理 Na/K 比值，这也得到了超氧自由基、过氧化氢、酚、过氧化物酶活性和超氧化物歧化酶活性的分析的支持。通过表达分析，我们鉴定出五个候选的 Vm_NHX 基因，其中四个，即 Vm_NHX16、Vm_NHX17、Vm_NHX29 和 Vm_NHX33，定位于液泡和溶酶体膜。
