School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
Shanghai Agrobiological Gene Center, Shanghai, 201106, People's Republic of China.
Plant Mol Biol. 2020 Jul;103(4-5):561-580. doi: 10.1007/s11103-020-01011-0. Epub 2020 May 13.
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 F/F, root length, biomass, and enhanced plant growth. The CmHKT1;1 gene may serve as a useful candidate for improving crop salt tolerance.
CmHKT1;1 选择性地将 Na 从植物细胞中输出。在 NaCl 胁迫下，其在耐盐甜瓜品种中的表达增加。过表达 CmHKT1;1 通过改善 K/Na 平衡增加了转基因拟南芥的耐盐性。高亲和力 K 转运体 (HKTs) 被认为参与减少盐胁迫下植物地上部分的 Na 并调节耐盐性，但它们在中度耐盐甜瓜（Cucumis melo L.）中的功能仍不清楚。在这项研究中，根据基因组数据从甜瓜中分离出一个 Na 转运基因 CmHKT1;1（GenBank 登录号：MK986658）。CmHKT1;1 的转录本在甜瓜幼苗的根中比在茎或叶中更为丰富。烟草瞬时表达系统表明 CmHKT1;1 定位于质膜。在盐胁迫下，与盐敏感品种‘玉露’（YL）相比，耐盐甜瓜品种‘冰雪脆’（BXC）中 CmHKT1;1 的表达上调更为强烈。电生理学证据表明，当在非洲爪蟾卵母细胞中表达时，CmHKT1;1 仅运输 Na，而不是 K。过表达 CmHKT1;1 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，转基因拟南芥植物地上部分的 Na 浓度明显低于野生型植物，表现出更好的 K/Na 平衡，导致更好的 F/F、根长、生物量和增强的植物生长。CmHKT1;1 基因可能是提高作物耐盐性的有用候选基因。
