Wu Xiaoqin, Chen Tong, Zheng Maozhong, Chen Yanmei, Teng Nianjun, Samaj Jozef, Baluska Frantisek, Lin Jinxing
Key Laboratory of Photosynthesis and Molecular Environment Physiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China.
J Proteome Res. 2008 Oct;7(10):4299-312. doi: 10.1021/pr800241u. Epub 2008 Aug 21.
Ca (2+) is an essential ion in the control of pollen germination and tube growth. However, the control of pollen tube development by Ca (2+) signaling and its interactions with cytoskeletal components, energy-providing pathways, and cell-expansion machinery remain elusive. Here, we used nifedipine (Nif) to study Ca (2+) functions in differential protein expression and other cellular processes in Pinus bungeana pollen tube growth. Proteomics analysis indicated that 50 proteins showed differential expression with varying doses of Nif. Thirty-four of these were homologous to previously reported proteins and were classified into different functional categories closely related to tip-growth machinery. Blocking the L-type Ca (2+) channel with Nif in the pollen tube membrane induced several early alterations within a short time, including a reduction of extracellular Ca (2+) influx and a subsequently dramatic decrease in cytosolic free Ca (2+) concentration ([Ca (2+)] c), concomitant with ultrastructural abnormalities and changes in the abundance of proteins involved in energy production and signaling. Secondary alterations included actin filament depolymerization, disrupted patterns of endocytosis/exocytosis, and cell wall remodeling, along with changes in the proteins involved in these processes. These results suggested that extracellular Ca (2+) influx was necessary for the maintenance of the typical tip-focused [Ca (2+)] c gradient in the P. bungeana pollen tube, and that reduced adenosine triphosphate production (ATP), depolymerization of the cytoskeleton, and abnormal endocytosis/exocytosis, together with enhanced rigidity of cell walls, were responsible for the growth arrest observed in pollen tubes treated with Nif.
钙离子（Ca²⁺）是控制花粉萌发和花粉管生长的必需离子。然而，Ca²⁺信号对花粉管发育的调控及其与细胞骨架成分、能量供应途径和细胞扩张机制的相互作用仍不清楚。在此，我们使用硝苯地平（Nif）来研究Ca²⁺在白皮松花粉管生长中蛋白质差异表达及其他细胞过程中的功能。蛋白质组学分析表明，50种蛋白质在不同剂量的Nif作用下呈现差异表达。其中34种与先前报道的蛋白质同源，并被归类为与顶端生长机制密切相关的不同功能类别。用Nif阻断花粉管膜上的L型Ca²⁺通道会在短时间内引发一些早期变化，包括细胞外Ca²⁺内流减少以及随后胞质游离Ca²⁺浓度（[Ca²⁺]c）急剧下降，同时伴有超微结构异常以及参与能量产生和信号传导的蛋白质丰度变化。继发性变化包括肌动蛋白丝解聚、内吞/外排模式紊乱和细胞壁重塑，以及参与这些过程的蛋白质变化。这些结果表明，细胞外Ca²⁺内流对于维持白皮松花粉管中典型的顶端聚焦[Ca²⁺]c梯度是必要的，而三磷酸腺苷（ATP）产生减少、细胞骨架解聚、内吞/外排异常以及细胞壁刚性增强共同导致了用Nif处理的花粉管中观察到的生长停滞。
