Overexpression of K2-NhaD in transgenic cotton resulted in phenotypes with strong salinity and drought tolerance in greenhouse and field experiments, increased expression of stress-related genes, and improved regulation of metabolic pathways, such as the SOS pathway. Drought and salinity are major abiotic stressors which negatively impact cotton yield under field conditions. Here, a plasma membrane Na+/H+ antiporter gene, K2-NhaD, was introduced into upland cotton R15 using an Agrobacterium tumefaciens-mediated transformation system. Homozygous transgenic lines K9, K17, and K22 were identified by PCR and glyphosate-resistance. TAIL-PCR confirmed that T-DNA carrying the K2-NhaD gene in transgenic lines K9, K17 and K22 was inserted into chromosome 3, 19 and 12 of the cotton genome, respectively. Overexpression of K2-NhaD in transgenic cotton plants grown in greenhouse conditions and subjected to drought and salinity stress resulted in significantly higher relative water content, chlorophyll, soluble sugar, proline levels, and SOD, CAT, and POD activity, relative to non-transgenic plants. The expression of stress-related genes was significantly upregulated, and this resulted in improved regulation of metabolic pathways, such as the salt overly sensitive pathway. K2-NhaD transgenic plants growing under field conditions displayed strong salinity and drought tolerance, especially at high levels of soil salinity and drought. Seed cotton yields in transgenic line were significantly higher than in wild-type plants. In conclusion, the data indicate that K2-NhaD transgenic lines have great potential for the production of stress-tolerant cotton under field conditions.

中文翻译：

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Na+/H+ 反转运蛋白 K2-NhaD 可提高棉花 (Gossypium hirsutum L.) 的耐盐性和耐旱性。

K2-NhaD 在转基因棉花中的过表达导致在温室和田间试验中具有强盐分和耐旱性的表型，增加了胁迫相关基因的表达，并改善了代谢途径（如 SOS 途径）的调节。干旱和盐分是主要的非生物胁迫源，它们在田间条件下对棉花产量产生负面影响。在这里，使用根癌农杆菌介导的转化系统将质膜 Na+/H+ 逆向转运蛋白基因 K2-NhaD 引入陆地棉 R15。通过 PCR 和草甘膦抗性鉴定纯合转基因系 K9、K17 和 K22。TAIL-PCR证实在转基因株系K9、K17和K22中携带K2-NhaD基因的T-DNA分别插入棉花基因组的3、19和12号染色体。与非转基因相比，在温室条件下生长并遭受干旱和盐分胁迫的转基因棉花植物中过表达 K2-NhaD 导致相对水分含量、叶绿素、可溶性糖、脯氨酸水平以及 SOD、CAT 和 POD 活性显着升高植物。应激相关基因的表达显着上调，这导致代谢途径的调节得到改善，例如盐过度敏感的途径。在田间条件下生长的 K2-NhaD 转基因植物表现出很强的盐分和干旱耐受性，尤其是在高水平的土壤盐分和干旱条件下。转基因株系的籽棉产量显着高于野生型植物。综上所述，