CmHKT1;1 selectively exports Na+ from plant cells. Upon NaCl stress, its expression increased in a salt-tolerant melon cultivar. Overexpression of CmHKT1;1 increased transgenic Arabidopsis salt tolerance through improved K+/Na+ balance. High-affinity K+ transporters (HKTs) are thought to be involved in reducing Na+ in plant shoots under salt stress and modulating salt tolerance, but their function in a moderately salt-tolerant species of melon (Cucumis melo L.) remains unclear. In this study, a Na+ transporter gene, CmHKT1;1 (GenBank accession number: MK986658), was isolated from melons based on genome data. The transcript of CmHKT1;1 was relatively more abundant in roots than in stems or leaves from melon seedlings. The tobacco transient expression system showed that CmHKT1;1 was plasma-membrane localized. Upon salt stress, CmHKT1;1 expression was more strongly upregulated in a salt-tolerant melon cultivar, 'Bingxuecui' (BXC) compared with a salt-sensitive cultivar, 'Yulu' (YL). Electrophysiological evidence demonstrated that CmHKT1;1 only transported Na+, rather than K+, when expressed in Xenopus laevis oocytes. Overexpression of CmHKT1;1 increased salt sensitivity in Saccharomyces cerevisiae and salt tolerance in Arabidopsis thaliana. Under NaCl treatments, transgenic Arabidopsis plants accumulated significantly lower concentrations of Na+ in shoots than wild type plants and showed a better K+/Na+ balance, leading to better Fv/Fm, root length, biomass, and enhanced plant growth. The CmHKT1;1 gene may serve as a useful candidate for improving crop salt tolerance.

中文翻译：

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来自甜瓜的 Na+ 转运蛋白 CmHKT1;1 通过改善 K+/Na+ 平衡在转基因拟南芥耐盐性中发挥支持作用。


CmHKT1;1 选择性地从植物细胞中输出 Na+。在 NaCl 胁迫下，其表达在耐盐甜瓜品种中增加。 CmHKT1;1 的过表达通过改善 K+/Na+ 平衡来增加转基因拟南芥的耐盐性。高亲和力 K+ 转运蛋白 (HKT) 被认为参与在盐胁迫下减少植物芽中的 Na+ 并调节耐盐性，但它们在中等耐盐甜瓜 (Cucumis melo L.) 物种中的功能仍不清楚。本研究根据基因组数据从甜瓜中分离出一个Na+转运蛋白基因CmHKT1;1（GenBank登录号：MK986658）。瓜苗根部中CmHKT1;1的转录本相对丰富于茎或叶中。烟草瞬时表达系统显示 CmHKT1;1 是质膜定位的。盐胁迫后，与盐敏感品种“玉露”(YL) 相比，耐盐甜瓜品种“冰雪翠”(BXC) 中 CmHKT1;1 表达上调更强烈。电生理学证据表明，当 CmHKT1;1 在非洲爪蟾卵母细胞中表达时，仅转运 Na+，而不是 K+。 CmHKT1;1 的过度表达增加了酿酒酵母的盐敏感性和拟南芥的耐盐性。在 NaCl 处理下，转基因拟南芥植物在芽中积累的 Na+ 浓度显着低于野生型植物，并表现出更好的 K+/Na+ 平衡，从而导致更好的 Fv/Fm、根长、生物量和增强的植物生长。 CmHKT1;1 基因可能作为提高作物耐盐性的有用候选基因。