Plasma membrane H+-ATPases sustain pollen tube growth and fertilization
Plasma membrane H+-ATPases sustain pollen tube growth and fertilization
复制标题
DOI：
10.1038/s41467-020-16253-1
复制
发表时间：
2020-05-14
影响因子：
16.6
通讯作者：
Palmgren, Michael
中科院分区：
文献类型：
--
作者：
Hoffmann, Robert D.;Portes, Maria Teresa;Palmgren, Michael
花粉管是高度极化的顶端生长细胞，其依赖于胞质pH梯度来进行信号传导和生长。自抑制质膜质子（H+）ATP酶（AHA）已被认为是激活花粉管生长和细胞极性的基础，但缺乏机制证据。在这里，我们报告说，在拟南芥AHA6，AHA8和AHA9的组合损失延迟花粉萌发，并导致花粉管生长缺陷，导致生育力急剧下降。AHA突变体的花粉管细胞外质子（H+）和阴离子通量减少，细胞质pH值降低，减少尖端到小腿质子梯度，和缺陷的肌动蛋白组织。此外，突变体的花粉管具有较少的负膜电位，证实了AHAs通过质膜超极化在花粉管生长中的机制作用。我们的研究结果将AHAs定义为维持离子回路的能量转换器，该离子回路定义了胞质pH的空间和时间分布，从而控制下游pH依赖性机制对花粉管伸长至关重要，从而控制植物生育力。花粉管生长过程中的胞质离子梯度被认为是极性生长所必需的。在这里，作者表明，拟南芥质膜H+ ATP酶，AHA6，AHA8和AHA9，保持尖端到柄质子梯度，振荡在细胞质pH值和肌动蛋白组织，使花粉管伸长。
Pollen tubes are highly polarized tip-growing cells that depend on cytosolic pH gradients for signaling and growth. Autoinhibited plasma membrane proton (H+) ATPases (AHAs) have been proposed to energize pollen tube growth and underlie cell polarity, however, mechanistic evidence for this is lacking. Here we report that the combined loss of AHA6, AHA8, and AHA9 in Arabidopsis thaliana delays pollen germination and causes pollen tube growth defects, leading to drastically reduced fertility. Pollen tubes of aha mutants had reduced extracellular proton (H+) and anion fluxes, reduced cytosolic pH, reduced tip-to-shank proton gradients, and defects in actin organization. Furthermore, mutant pollen tubes had less negative membrane potentials, substantiating a mechanistic role for AHAs in pollen tube growth through plasma membrane hyperpolarization. Our findings define AHAs as energy transducers that sustain the ionic circuit defining the spatial and temporal profiles of cytosolic pH, thereby controlling downstream pH-dependent mechanisms essential for pollen tube elongation, and thus plant fertility. Cytosolic ion gradients in growing pollen tubes are thought to be required for polar growth. Here the authors show that the Arabidopsis plasma membrane H+ ATPases, AHA6, AHA8, and AHA9, maintain tip-to-shank proton gradients, oscillations in cytosolic pH and actin organization to enable pollen tube elongation.