National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China
Plant Physiol. 2018 Apr;176(4):2977-2990. doi: 10.1104/pp.17.01472. Epub 2018 Feb 12.
Glc regulates many vital processes, including plant growth, development, metabolism, and responses to biotic and abiotic stress. However, the molecular mechanism by which Glc acts as a signal to regulate salinity tolerance remains unclear. In this study, we found that the apple ( Borkh.) Glc sensor hexokinase1 (MdHXK1) contributes to Glc-mediated salinity tolerance. A combination of split ubiquitin system, pull-down, co-immunoprecipitation, and bimolecular fluorescence complementation assays demonstrated that MdHXK1 interacts with and phosphorylates the Na/H exchanger MdNHX1 at its Ser-275 residue. Phosphorylation improved the stability of MdNHX1 and enhanced its Na/H transport activity in overexpression transgenic apple and yeast complementation cells. Furthermore, Ser-275 of MdNHX1 was found to be crucial for MdHXK1-mediated phosphorylation. Finally, a series of transgenic analyses demonstrated that salt tolerance mediated by MdHXK1 partially depended on MdNHX1. Overall, our findings provide insights into how sugar recruits and regulates MdNHX1 in response to high salinity in plants.
葡萄糖（Glc）调控许多重要的过程，包括植物的生长、发育、代谢以及对生物和非生物胁迫的响应。然而，葡萄糖作为信号调节耐盐性的分子机制仍不清楚。在本研究中，我们发现苹果（Borkh.）葡萄糖感受器己糖激酶 1（MdHXK1）有助于葡萄糖介导的耐盐性。分裂泛素系统、下拉、共免疫沉淀和双分子荧光互补测定的组合表明，MdHXK1 与 Na+/H+逆向转运蛋白 MdNHX1 相互作用，并在其 Ser-275 残基上磷酸化 MdNHX1。磷酸化提高了 MdNHX1 的稳定性，并增强了其在过表达转基因苹果和酵母互补细胞中的 Na+/H+转运活性。此外，发现 MdNHX1 的 Ser-275 残基对于 MdHXK1 介导的磷酸化至关重要。最后，一系列转基因分析表明，MdHXK1 介导的盐耐受性部分依赖于 MdNHX1。总的来说，我们的研究结果提供了有关植物在高盐胁迫下糖如何招募和调节 MdNHX1 的见解。
