The nhaA gene conferring Na⁺/H⁺ antiporter activity was used to discriminate salt tolerant plant growth promoting bacteria isolated from Western Himalayas. Fifty two isolates were obtained from rhizospheric soil of four different plants growing around the salt mines of Himachal Pradesh (India). Only six isolates were found to tolerate salt up to 1.7 M NaCl and identified by 16S rRNA typing techniques. A phylogenetic tree grouped these native strains into two clusters, first comprising Bacillus and second Enterobacter strains along with strains from different countries. The plant growth promoting traits of selected bacteria were studied under salt stress (0.86 M NaCl) to expose functional divergence. At genetic level, nhaA gene sequences of native strains were compared with other lineages available in literature. The phylogenetic tree obtained from mining of nhaA gene and distance matrix index values showed significant variations in gene sequences of salt tolerant native strains in comparison to exotic non salt tolerant strains. The deduced NhaA protein of these strains showed variations in their putative secondary structure. The sequence variation of nhaA gene revealed it to be an appropriate marker to differentiate among native salt tolerant and non salt tolerant strains.

中文翻译：

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喜马拉雅西部耐盐和植物生长的根瘤菌遗传变异

赋予Na ⁺ / H ⁺反转运蛋白活性的nhaA基因用于区分从西喜马拉雅山分离的耐盐植物生长促进细菌。从在喜马al尔邦（印度）盐矿周围生长的四种不同植物的根际土壤中获得了52种分离株。发现仅六个分离物可耐受高达1.7 M NaCl的盐，并通过16S rRNA分型技术进行了鉴定。系统发育树将这些天然菌株分为两个簇，第一个簇包括芽孢杆菌和第二个肠杆菌菌株以及来自不同国家的菌株。在盐胁迫（0.86 M NaCl）下研究所选细菌的植物生长促进特性，以揭示功能差异。在遗传水平上，将天然菌株的nhaA基因序列与文献中可获得的其他谱系进行了比较。通过挖掘nhaA基因和距离矩阵指数值获得的系统发育树显示，与外来的非耐盐菌株相比，耐盐天然菌株的基因序列有显着变化。这些菌株的推导的NhaA蛋白在其推定的二级结构中显示出变异。nhaA的序列变异 该基因表明它是区分天然耐盐和非耐盐菌株的合适标记。