Nitric oxide is involved in growth regulation and re-orientation of pollen tubes
Nitric oxide is involved in growth regulation and re-orientation of pollen tubes
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DOI：
10.1242/dev.01153
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发表时间：
2004-06-01
期刊：
影响因子：
4.6
通讯作者：
Feijó, JA
中科院分区：
文献类型：
--
作者：
Prado, AM;Porterfield, DM;Feijó, JA
一氧化氮(NO)控制着动物许多细胞和器官的多种功能。它也是在植物中产生的，具有多种影响，但对其潜在机制知之甚少。在目前的研究中，我们发现了NO在调节花粉管生长中的作用，花粉管生长是一种快速生长的细胞系统。花粉管必须精确定位在解剖结构复杂的雌性卵巢内，才能传递精子。我们假设NO可以在这一指导中发挥作用，并通过挑战外部NO点源对花粉管生长的挑战来检验这一假设。当检测到一个临界浓度时，生长速度减慢，生长轴随后经历急剧的重新定向，之后达到正常生长。这种反应在NO清除剂CPTiO存在的情况下被取消，并被干扰cGMP信号通路的药物影响。柠檬酸西地那非(SC)是一种动物中cGMP特异性磷酸二酯酶的抑制剂，显著提高了反应的敏感性阈值。用DAF2-DA研究了NO在花粉管内的分布，结果表明，NO主要存在于过氧化体中。花粉管顶端通常不含过氧化物体，而该区域的细胞质中几乎没有。我们的数据表明，花粉管生长的速度和方向受到花粉管顶端NO水平的调节，并表明这种作用是由cGMP介导的。
Nitric oxide (NO) controls diverse functions in many cells and organs of animals. It is also produced in plants and has a variety of effects, but little is known about their underlying mechanisms. In the present study, we have discovered a role for NO in the regulation of pollen tube growth, a fast tip-growing cellular system. Pollen tubes must be precisely oriented inside the anatomically complex female ovary in order to deliver sperm. We hypothesized that NO could play a role in this guidance and tested this hypothesis by challenging the growth of pollen tubes with an external NO point source. When a critical concentration was sensed, the growth rate was reduced and the growth axis underwent a subsequent sharp reorientation, after which normal growth was attained. This response was abrogated in the presence of the NO scavenger CPTIO and affected by drugs interfering in the cGMP signaling pathway. The sensitivity threshold of the response was significantly augmented by sildenafil citrate (SC), an inhibitor of cGMP-specific phosphodiesterases in animals. NO distribution inside pollen tubes was investigated using DAF2-DA and was shown to occur mostly in peroxisomes. Peroxisomes are normally excluded from the tip of pollen tubes and little if any NO is found in the cytosol of that region. Our data indicate that the rate and orientation of pollen tube growth is regulated by NO levels at the pollen tube tip and suggest that this NO function is mediated by cGMP.