The sodium/proton exchanger (NHX) mediates Na⁺ and H⁺ countertransport in plants and plays an important role in regulating intracellular pH and maintaining ion and osmotic balance. Previously, an NHX1 orthologue was isolated from the halophyte Nitraria sibirica Pall (referred to as NsNHX1), and its role in enhancing salt tolerance of transgenic Arabidopsis was confirmed. To further analyse its features and functions, the 1311-bp sequence of the NsNHX1 promoter was cloned, and histochemical staining showed that β-glucuronidase (GUS) expression driven by the NsNHX1 promoter was strongly induced by abiotic stress and phytohormones, such as salt, drought, gibberellins, and methyl jasmonate, in turn indicating that NsNHX1 might participate in the regulation of various signalling pathways. To determine how NsNHX1 regulates salt tolerance in forestry trees, NsNHX1 was introduced into 84K poplar, and salt tolerance analysis of transgenic poplars showed that overexpression of NsNHX1 increased the overall biomass, survival rate, and plant height, and the contents of chlorophyll, proline and water, all of which are consequences of antioxidant enzyme activity under salt stress conditions. This showed that overexpression of NsNHX1 enhanced the salt tolerance of transgenic poplars as a result of NsNHX1-mediated Na⁺ compartmentalisation, more efficient photosynthesis, greater activity of antioxidant enzymes, and improved osmotic adjustment. Moreover, overexpression of NsNHX1 enhanced the root development of transgenic poplars; this resulted in increased biomass and height under normal and salt stress conditions, likely due to coupling between NsNHX1 and membrane proton pumps. These results provided a theoretical and experimental basis for further understanding the function and regulatory mechanism of NsNHX1, as well as its application for genetic improvement of forestry trees.

钠/质子交换剂（NHX）介导植物中的Na ⁺和H ⁺逆向转运，并且在调节细胞内pH值以及维持离子和渗透平衡方面起着重要作用。以前，一个NHX1直向同源物是从盐生植物中分离白刺帕尔（简称NsNHX1），和它在提高转基因的耐盐性的作用拟南芥中得到证实。为了进一步分析其特征和功能，克隆了NsNHX1启动子的1311 bp序列，并且组织化学染色显示NsNHX1驱动了β-葡萄糖醛酸苷酶（GUS）的表达。该启动子受到非生物胁迫和植物激素（如盐，干旱，赤霉素和茉莉酸甲酯）的强烈诱导，进而表明NsNHX1可能参与了各种信号通路的调控。为了确定NsNHX1如何调节林业树木的耐盐性，将NsNHX1引入到84K杨树中，对转基因杨树的耐盐性分析表明，NsNHX1的过表达增加了整体生物量，存活率和株高，并增加了叶绿素，脯氨酸和水，所有这些都是盐胁迫条件下抗氧化酶活性的结果。这表明NsNHX1的过度表达NsNHX1介导的Na ⁺间隔化增强了转基因杨树的耐盐性，提高了光合作用的效率，增强了抗氧化酶的活性，并改善了渗透调节。此外，NsNHX1的过表达增强了转基因杨树的根系发育。这可能是由于NsNHX1和膜质子泵之间的耦合，导致在正常和盐胁迫条件下生物量和高度增加。这些结果为进一步了解NsNHX1的功能和调控机制及其在林木遗传改良中的应用提供了理论和实验依据。