Rajappa Sivamathini, Krishnamurthy Pannaga, Kumar Prakash P
Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
NUS Environmental Research Institute (NERI), National University of Singapore, Singapore, Singapore.
Front Plant Sci. 2020 Aug 25;11:1311. doi: 10.3389/fpls.2020.01311. eCollection 2020.
Potassium transporters play an essential role in maintaining cellular ion homeostasis, turgor pressure, and pH, which are critical for adaptation under salt stress. We identified a salt responsive KUP/HAK/KT transporter family gene, , which has high sequence similarity to its ortholog . These genes were functionally characterized in mutant yeast cells and plants. Both and were induced by salt stress, and was primarily induced in roots. Subcellular localization revealed that AoKUP2 and AtKUP2 are localized to the plasma membrane and mitochondria. Expression of and in mutant strain (BY4741 ΔΔ) helped to rescue the growth defect of the mutant under different NaCl and K concentrations. Furthermore, constitutive expression of and conferred enhanced salt tolerance in indicated by higher germination rate, better survival, and increased root and shoot length compared to the untreated controls. Analysis of Na and K contents in the shoots and roots showed that ectopic expression lines accumulated less Na and more K than the WT. Two stress-responsive transcription factors, bHLH122 and WRKY33, were identified as direct regulators of expression. Our results suggest that AtKUP2 plays a key role in enhancing salt stress tolerance by maintaining cellular ion homeostasis.
钾转运体在维持细胞离子稳态、膨压和pH值方面发挥着重要作用，而这些对于盐胁迫下的适应至关重要。我们鉴定出一个盐响应性KUP/HAK/KT转运体家族基因， ，它与其直系同源基因 具有高度的序列相似性。这些基因在突变酵母细胞和 植物中进行了功能表征。 和 均受盐胁迫诱导，且 主要在根中诱导表达。亚细胞定位显示，AoKUP2和AtKUP2定位于质膜和线粒体。 和 在 突变菌株（BY4741 ΔΔ）中的表达有助于挽救突变体在不同NaCl和K浓度下的生长缺陷。此外， 和 的组成型表达赋予 增强的耐盐性，与未处理的对照相比，发芽率更高、存活率更高且根和茎长度增加。对地上部和根部Na 和K 含量的分析表明，异位表达系比野生型积累的Na 更少且K 更多。两个胁迫响应转录因子bHLH122和WRKY33被鉴定为 表达的直接调节因子。我们的结果表明，AtKUP2通过维持细胞离子稳态在增强盐胁迫耐受性中起关键作用。
