Control of vacuolar dynamics and regulation of stomatal aperture by tonoplast potassium uptake
Control of vacuolar dynamics and regulation of stomatal aperture by tonoplast potassium uptake
复制标题
DOI：
10.1073/pnas.1320421111
复制
发表时间：
2014-04-29
影响因子：
11.1
通讯作者：
Pardo, Jose M.
中科院分区：
文献类型：
--
作者：
Andres, Zaida;Perez-Hormaeche, Javier;Pardo, Jose M.
气孔运动依赖于保卫细胞膨压的变化。这需要大量的 K+ 双向通量穿过质膜和液泡膜。令人惊讶的是，考虑到其生理重要性，介导 K+ 向上输送至液泡的转运蛋白仍有待鉴定。在这里，我们报道，在拟南芥保卫细胞中，液泡膜定位的 K+/H+ 交换器 NHX1 和 NHX2 在 K+ 的液泡积累中至关重要，并且 nhx1 nhx2 突变系在气孔调节中功能障碍。亚形性和完全功能丧失的双突变体表现出显着受损的气孔打开和关闭反应。保卫细胞中 K+ 积累的破坏与更多的酸性液泡以及与气孔运动相关的液泡结构的高度动态重塑的消失相关。我们的研究结果表明，保卫细胞液泡中 K+ 的积累是气孔开放的必要条件，也是气孔关闭所必需的整体 K+ 稳态的关键组成部分，并且表明液泡 K+ 通量对于气孔运动背后的液泡动力学和管腔 pH 值的调节也具有决定性的重要性。
Stomatal movements rely on alterations in guard cell turgor. This requires massive K+ bidirectional fluxes across the plasma and tonoplast membranes. Surprisingly, given their physiological importance, the transporters mediating the energetically uphill transport of K+ into the vacuole remain to be identified. Here, we report that, in Arabidopsis guard cells, the tonoplast-localized K+/H+ exchangers NHX1 and NHX2 are pivotal in the vacuolar accumulation of K+ and that nhx1 nhx2 mutant lines are dysfunctional in stomatal regulation. Hypomorphic and complete-loss-of-function double mutants exhibited significantly impaired stomatal opening and closure responses. Disruption of K+ accumulation in guard cells correlated with more acidic vacuoles and the disappearance of the highly dynamic remodelling of vacuolar structure associated with stomatal movements. Our results show that guard cell vacuolar accumulation of K+ is a requirement for stomatal opening and a critical component in the overall K+ homeostasis essential for stomatal closure, and suggest that vacuolar K+ fluxes are also of decisive importance in the regulation of vacuolar dynamics and luminal pH that underlie stomatal movements.