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

叶绿体内的NHX1和NHX2交换体是参与K+营养、Na+耐受和pH稳态的阳离子/H+反转运体。为了发挥作用，NHX反转运蛋白需要一个横跨细胞质的H+梯度，在植物细胞中，这个梯度是由两个H+泵，液泡H+- atp酶（V-ATPase）和液泡H+-焦磷酸酶（V-PPase）共同作用产生的。因此，普遍存在的V-PPase、NHX交换器或两者的组合的过表达已被广泛用于创造耐受非生物胁迫的植物的策略。然而，转基因品系获得这些有益性状的机制尚不清楚。我们的初步数据表明，V-PPase和NHX蛋白相互作用，相互依赖，以控制钾稳态和细胞伸长。此外，研究结果表明，V-PPase在气孔运动动力学中起主要作用。因此，我的主要目标是研究在不同的外部条件下，细胞膜V-PPase和NHX转运体如何协调它们的活动来维持离子和pH的稳态。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发育。其次，我将研究V-PPase在保护细胞功能中的作用及其与应激耐受反应的联系。

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.