Study of the interplay between the V-PPase and tonoplast-localise NHX antiporters in ion and pH homeostasis

液泡膜定位NHX 1和NHX 2交换器是阳离子/H+反向转运蛋白，参与K+营养、Na+耐受和pH稳态。为了发挥作用，NHX反向转运蛋白需要跨液泡膜的H+梯度，其在植物细胞中由两个H+泵，液泡H+-ATP酶（V-ATP酶）和液泡H+-焦磷酸酶（V-PPase）的组合作用产生。因此，V-PPase、NHX交换剂或两者的组合的普遍过表达已成为产生对非生物胁迫的耐受性植物的广泛使用的策略。然而，在转基因株系中获得有益性状的机制仍然未知。我们的初步数据表明，V-PPase和NHX蛋白的物理相互作用和相互依赖，以控制钾稳态和细胞伸长。此外，研究结果表明，在气孔运动动力学的V-PPase的主要作用。因此，我的主要目标是研究液泡膜V-PPase和NHX转运蛋白如何协调其活动，以维持离子和pH稳态在不同的外部条件下。首先，我将研究它们的功能和物理相互作用以及它们的转录后修饰如何影响植物的生长和发育。其次，我将研究V-PPase在保卫细胞功能中的作用及其与胁迫耐受反应的关系。

The tonoplast-localise NHX1 and NHX2 exchangers are cation/H+ antiporters involved in K+ nutrition, Na+ tolerance and pH homeostasis. To function, NHX antiporters need a H+ gradient across the tonoplast that in plant cells is generated by the combined action of two H+-pumps, the vacuolar H+-ATPase (V-ATPase) and the vacuolar H+-pyrophosphatase (V-PPase). Thus, ubiquitous overexpression of the V-PPase, the NHX exchangers or a combination of both has been a largely used strategy to create tolerant plants to abiotic stresses. However, the mechanism by which the beneficial traits are gained in the transgenic lines remains unknown. Our preliminary data show that the V-PPase and the NHX proteins physically interact and depend on each other to control potassium homeostasis and cell elongation. Additionally, the results suggest a main role of the V-PPase in the stomatal movements kinetics. Therefore, my main goal is to investigate how the tonoplast V-PPase and NHX transporters coordinate their activities to maintain ion and pH homeostasis under different external conditions. First I will study how their functional and physical interactions and their post-transcriptional modifications influence plant growth and development. Second, I will investigate the role of the V-PPase in guard cell function and its connection with stress tolerance responses.