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近日，中科院植物所林金星研究组利用细胞生物学手段，深入研究了裸子植物白皮松花粉管生长过程中，一氧化氮（NO）对钙离子、微丝骨架、囊泡转运和细胞壁构建的调节作用。该成果发表在New Phytologist（2009，182(4): 851-862）杂志上。 NO作为重要的信号分子，参与调控花粉管极性生长。通过应用显微注射、非损伤微测、免疫荧光标记等技术，研究人员发现：NO释放剂促进花粉萌发和花粉管伸长，并且具有浓度效应，而抑制剂则抑制花粉萌发和花粉管生长，具有浓度效应，同时使花粉管顶端膨大，丧失极性；NO释放剂促进胞外Ca2+内流，顶端Ca2+浓度梯度增加，NO抑制剂抑制胞外Ca2+内流，顶端Ca2+浓度梯度降低；NO释放剂还能够促进囊泡运输，使花粉管顶端的细微丝束解聚，相反，NO抑制剂抑制囊泡运输，促进花粉管中微丝聚合，尤其在花粉管顶端形成粗的微丝束，并一直延伸到花粉管的最顶端；此外，NO使花粉管顶端酯化果胶增加而酸性果胶降低。 研究结果说明：在白皮松花粉管中，NO促进胞外Ca2+内流，从而维持胞内Ca2+浓度梯度，进而影响花粉管顶端微丝骨架的组装，促进囊泡运输，使花粉管顶端酯化果胶累积，最终促进花粉管的正常生长。 推荐原始出处： New Phytologist 31 Mar 2009 DOI:10.1111/j.1469-8137.2009.02820.x Nitric oxide modulates the influx of extracellular Ca2+ and actin filament organization during cell wall construction in Pinus bungeana pollen tubes Yuhua Wang 1,2,3 , Tong Chen 1 , Chunyang Zhang 1,2 , Huaiqing Hao 1 , Peng Liu 1,2 , Maozhong Zheng 1,2 , Franti?ek Balu?ka 4 , Jozef ?amaj 4,5,6 and Jinxing Lin 1 1 Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China ; 2 Graduate School of Chinese Academy of Sciences, Beijing 100049, China ; 3 The College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China ; 4 Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Kirschallee 1, D-53115 Bonn, Germany ; 5 Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademicka 2, SK-95007, Nitra, Slovak Republic ; 6 Palacky University Olomouc, Faculty of Natural Science, Olomouc 771 46, Czech Republic Nitric oxide (NO) plays a key role in many physiological processes in plants, including pollen tube growth. Here, effects of NO on extracellular Ca2+ flux and microfilaments during cell wall construction in Pinus bungeana pollen tubes were investigated. Extracellular Ca2+ influx, the intracellular Ca2+ gradient, patterns of actin organization, vesicle trafficking and cell wall deposition upon treatment with the NO donor S-nitroso-N-acetylpenicillamine (SNAP), the NO synthase (NOS) inhibitor Nω-nitro-L-arginine (L-NNA) or the NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) were analyzed. SNAP enhanced pollen tube growth in a dose-dependent manner, while L-NNA and cPTIO inhibited NO production and arrested pollen tube growth. Noninvasive detection and microinjection of a Ca2+ indicator revealed that SNAP promoted extracellular Ca2+ influx and increased the steepness of the tip-focused Ca2+ gradient, while cPTIO and L-NNA had the opposite effect. Fluorescence labeling indicated that SNAP, cPTIO and L-NNA altered actin organization, which subsequently affected vesicle trafficking. Finally, the configuration and/or distribution of cell wall components such as pectins and callose were significantly altered in response to L-NNA. Fourier transform infrared (FTIR) microspectroscopy confirmed the changes in the chemical composition of walls. Our results indicate that NO affects the configuration and distribution of cell wall components in pollen tubes by altering extracellular Ca2+ influx and F-actin organization. (责任编辑：Doctor001) |
