An Dong, Chen Jiu-Geng, Gao Yi-Qun, Li Xiang, Chao Zhen-Fei, Chen Zi-Ru, Li Qian-Qian, Han Mei-Ling, Wang Ya-Ling, Wang Yong-Fei, Chao Dai-Yin
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
College of Agriculture and Biology, Shanghai Jiao Tong University (SJTU), Shanghai, China.
PLoS Genet. 2017 Oct 30;13(10):e1007086. doi: 10.1371/journal.pgen.1007086. eCollection 2017 Oct.
Arabidopsis thaliana high-affinity potassium transporter 1 (AtHKT1) limits the root-to-shoot sodium transportation and is believed to be essential for salt tolerance in A. thaliana. Nevertheless, natural accessions with 'weak allele' of AtHKT1, e.g. Tsu-1, are mainly distributed in saline areas and are more tolerant to salinity. These findings challenge the role of AtHKT1 in salt tolerance and call into question the involvement of AtHKT1 in salinity adaptation in A. thaliana. Here, we report that AtHKT1 indeed drives natural variation in the salt tolerance of A. thaliana and the coastal AtHKT1, so-called weak allele, is actually hyper-functional in reducing flowers sodium content upon salt stress. Our data showed that AtHKT1 positively contributes to saline adaptation in a linear manner. Forward and reverse genetics analysis established that the single AtHKT1 locus is responsible for the variation in the salinity adaptation between Col-0 and Tsu-1. Reciprocal grafting experiments revealed that shoot AtHKT1 determines the salt tolerance of Tsu-1, whereas root AtHKT1 primarily drives the salt tolerance of Col-0. Furthermore, evidence indicated that Tsu-1 AtHKT1 is highly expressed in stems and is more effective compared to Col-0 AtHKT1 at limiting sodium flow to the flowers. Such efficient retrieval of sodium to the reproductive organ endows Tsu-1 with stronger fertility compared to Col-0 upon salt stress, thus improving Tsu-1 adaptation to a coastal environment. To conclude, our data not only confirm the role of AtHKT1 in saline adaptation, but also sheds light on our understanding of the salt tolerance mechanisms in plants.
拟南芥高亲和钾转运体1（AtHKT1）限制了根到地上部的钠运输，被认为是拟南芥耐盐性所必需的。然而，具有AtHKT1“弱等位基因”的自然生态型，如Tsu-1，主要分布在盐碱地区，并且对盐分更具耐受性。这些发现挑战了AtHKT1在耐盐性中的作用，并对AtHKT1参与拟南芥盐分适应提出了质疑。在此，我们报告AtHKT1确实驱动了拟南芥耐盐性的自然变异，并且沿海的AtHKT1，即所谓的弱等位基因，在盐胁迫下降低花中钠含量方面实际上具有超功能。我们的数据表明，AtHKT1以线性方式对盐分适应有积极贡献。正向和反向遗传学分析表明，单一的AtHKT1基因座负责Col-0和Tsu-1之间盐分适应的变异。相互嫁接实验表明，地上部的AtHKT1决定了Tsu-1的耐盐性，而根部的AtHKT1主要驱动Col-0的耐盐性。此外，有证据表明，Tsu-1 AtHKT1在茎中高度表达，并且在限制钠流向花方面比Col-0 AtHKT1更有效。与Col-0相比，这种将钠有效地回收到生殖器官的能力使Tsu-1在盐胁迫下具有更强的育性，从而提高了Tsu-1对沿海环境的适应性。总之，我们的数据不仅证实了AtHKT1在盐分适应中的作用，还为我们理解植物的耐盐机制提供了新的线索。
