A sodium hydrogen exchanger (NHX) gene from the date palm enhances tolerance to salinity in Arabidopsis plants. Plant sodium hydrogen exchangers/antiporters (NHXs) are pivotal regulators of intracellular Na+/K+ and pH homeostasis, which is essential for salt stress adaptation. In this study, a novel orthologue of Na+/H+ antiporter was isolated from date palm (PdNHX6) and functionally characterized in mutant yeast cells and Arabidopsis plants to assess the behavior of the transgenic organisms in response to salinity. Genetically transformed yeast cells with PdNHX6 were sensitive to salt stress when compared to the empty vector (EV) yeast cells. Besides, the acidity value of the vacuoles of the transformant yeast cells has significantly (p ≤ 0.05) increased, as indicated by the calibrated fluorescence intensity measurements and the fluorescence imagining analyses. This observation supports the notion that PdNHX6 might regulate proton pumping into the vacuole, a crucial salt tolerance mechanism in the plants. Consistently, the transient overexpression and subcellular localization revealed the accumulation of PdNHX6 in the tonoplast surrounding the central vacuole of Nicotiana benthamiana leaf epidermal cells. Stable overexpression of PdNHX6 in Arabidopsis plants enhanced tolerance to salt stress and retained significantly higher chlorophyll, water contents, and increased seed germination under salinity when compared to the wild-type plants. Despite the significant increase of Na+, transgenic Arabidopsis lines maintained a balanced Na+/K+ ratio under salt stress conditions. Together, the results obtained from this study imply that PdNHX6 is involved in the salt tolerance mechanism in plants by controlling K+ and pH homeostasis of the vacuoles.

中文翻译：

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来自枣椰树的新型液泡膜 Na+/H+ 逆向转运体基因 (PdNHX6) 增强了拟南芥的耐盐性反应。

来自枣椰树的钠氢交换剂 (NHX) 基因增强了拟南芥植物对盐分的耐受性。植物钠氢交换剂/逆向转运体 (NHXs) 是细胞内 Na+/K+ 和 pH 稳态的关键调节剂，这对于适应盐胁迫至关重要。在这项研究中，从枣椰树 (PdNHX6) 中分离出一种新的 Na+/H+ 逆向转运蛋白直向同源物，并在突变酵母细胞和拟南芥植物中进行功能表征，以评估转基因生物对盐度的反应行为。与空载体 (EV) 酵母细胞相比，具有 PdNHX6 的基因转化酵母细胞对盐胁迫敏感。此外，转化酵母细胞液泡的酸度值显着增加（p≤0.05），如校准的荧光强度测量和荧光成像分析所示。这一观察结果支持了 PdNHX6 可能调节质子泵入液泡的观点，这是植物中一种重要的耐盐机制。一致地，瞬时过表达和亚细胞定位揭示了 PdNHX6 在烟草叶表皮细胞中央液泡周围的液泡中的积累。与野生型植物相比，拟南芥植物中 PdNHX6 的稳定过表达增强了对盐胁迫的耐受性，并保留了显着更高的叶绿素、水分含量和增加的种子发芽率。尽管 Na+ 显着增加，转基因拟南芥品系在盐胁迫条件下保持平衡的 Na+/K+ 比率。一起，