Pollen tube NAD(P)H oxidases act as a speed control to dampen growth rate oscillations during polarized cell growth
Pollen tube NAD(P)H oxidases act as a speed control to dampen growth rate oscillations during polarized cell growth
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DOI：
10.1111/tpj.12452
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发表时间：
2014-04-01
期刊：
影响因子：
7.2
通讯作者：
Romeis, Tina
中科院分区：
文献类型：
--
作者：
Lassig, Roman;Gutermuth, Timo;Romeis, Tina
由NAD（P）H氧化酶产生的活性氧在植物的逆境反应和发育过程中起着重要作用。为了更好地理解NAD（P）H氧化酶在植物发育中的功能，我们对拟南芥NAD（P）H氧化酶RBOHH和RBOHJ进行了表征。这两种蛋白质在花粉中特异性表达，并动态靶向不同的和重叠的质膜结构域在花粉管尖端。纯合双突变体中RBOHH和RBOHJ的功能丧失导致生育力降低。花粉管生长分析表明，Col-0和rbohh-1、rbohj-2花粉管的生长动态存在显著差异。rbohh-1 rbohj-2花粉管的生长速率振荡在振幅和频率上表现出强烈的波动，最终导致花粉管塌陷。在解体之前，rbohh-1 rbohj-2花粉管表现出高频率的生长振荡，具有显著升高的生长速率，这表明细胞壁胞吐速率的增加先于花粉管崩溃。对胞吐动力学的延时成像显示，NAD（P）H氧化酶减慢了花粉管生长，以协调细胞扩张速率与胞吐速率，从而抑制了内在生长振荡的幅度。使用Ca 2+报告基因Yellow Cameleon 3.6，我们证明rbohh-1 rbohj-2花粉管中的高振幅生长速率振荡与生长依赖性Ca 2+爆发相关。双突变体花粉管电生理实验和药物处理也表明ROS影响K+稳态。我们的研究结果表明，通过限制花粉管生长，由NAD（P）H氧化酶产生的ROS调节花粉管生长速率振荡的幅度和频率。
Reactive oxygen species (ROS) produced by NAD(P)H oxidases play a central role in plant stress responses and development. To better understand the function of NAD(P)H oxidases in plant development, we characterized the Arabidopsis thaliana NAD(P)H oxidases RBOHH and RBOHJ. Both proteins were specifically expressed in pollen and dynamically targeted to distinct and overlapping plasma membrane domains at the pollen tube tip. Functional loss of RBOHH and RBOHJ in homozygous double mutants resulted in reduced fertility. Analyses of pollen tube growth revealed remarkable differences in growth dynamics between Col-0 and rbohh-1 rbohj-2 pollen tubes. Growth rate oscillations of rbohh-1 rbohj-2 pollen tubes showed strong fluctuations in amplitude and frequency, ultimately leading to pollen tube collapse. Prior to disintegration, rbohh-1 rbohj-2 pollen tubes exhibit high-frequency growth oscillations, with significantly elevated growth rates, suggesting that an increase in the rate of cell-wall exocytosis precedes pollen tube collapse. Time-lapse imaging of exocytic dynamics revealed that NAD(P)H oxidases slow down pollen tube growth to coordinate the rate of cell expansion with the rate of exocytosis, thereby dampening the amplitude of intrinsic growth oscillations. Using the Ca2+ reporter Yellow Cameleon3.6, we demonstrate that high-amplitude growth rate oscillations in rbohh-1 rbohj-2 pollen tubes are correlated with growth-dependent Ca2+ bursts. Electrophysiological experiments involving double mutant pollen tubes and pharmacological treatments also showed that ROS influence K+ homeostasis. Our results indicate that, by limiting pollen tube growth, ROS produced by NAD(P)H oxidases modulate the amplitude and frequency of pollen tube growth rate oscillations.