Dynamic 1-Aminocyclopropane-1-Carboxylate-Synthase and -Oxidase Transcript Accumulation Patterns during Pollen Tube Growth in Tobacco Styles1
Dynamic 1-Aminocyclopropane-1-Carboxylate-Synthase and -Oxidase Transcript Accumulation Patterns during Pollen Tube Growth in Tobacco Styles1
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DOI：
10.1104/pp.007831
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发表时间：
2002-11
期刊：
影响因子：
7.4
通讯作者：
K. Weterings;M. Pezzotti;M. Cornelissen;C. Mariani
中科院分区：
文献类型：
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作者：
K. Weterings;M. Pezzotti;M. Cornelissen;C. Mariani
在开花植物中，柱头的授粉在远端花器官中引发了一连串的反应。乙烯及其生物合成前体1-氨基环丙烷-1-羧酸(ACC)在调节这些反应中起着重要作用。由于外源乙烯或ACC的应用不会引发授粉后综合征，授粉信号可能由一组更复杂的刺激组成。我们通过分析雌蕊表达的ACC合成酶和氧化酶基因的表达模式，研究授粉信号如何以及何时通过烟草花柱传递。分析结果表明，授粉在传递组织的所有细胞中都诱导了高水平的ACC-氧化酶转录本。ACC-合酶mRNA仅在部分传输道细胞中积累，与ACC-氧化酶相比，其表达水平较低。更重要的是，我们发现，尽管ACC-氧化酶转录物积累到统一的高水平，但ACC-合成酶转录物以波状模式积累，其中峰值与嵌入的花粉管顶端的前面重合。这波ACC合酶的表达也可以由不协调授粉和(部分)伤害诱导。这表明，花粉管侵入的类似伤害的特征可能是激发授粉后反应的刺激的一部分，而且这些刺激被ACC-合成酶和-氧化酶基因的调控机制解释得不同。
In flowering plants, pollination of the stigma sets off a cascade of responses in the distal flower organs. Ethylene and its biosynthetic precursor 1-aminocyclopropane-1-carboxylate (ACC) play an important role in regulating these responses. Because exogenous application of ethylene or ACC does not invoke the full postpollination syndrome, the pollination signal probably consists of a more complex set of stimuli. We set out to study how and when the pollination signal moves through the style of tobacco (Nicotiana tabacum) by analyzing the expression patterns of pistil-expressed ACC-synthase and -oxidase genes. Results from this analysis showed that pollination induces high ACC-oxidase transcript levels in all cells of the transmitting tissue. ACC-synthase mRNA accumulated only in a subset of transmitting tract cells and to lower levels as compared with ACC-oxidase. More significantly, we found that although ACC-oxidase transcripts accumulate to uniform high levels, the ACC-synthase transcripts accumulate in a wave-like pattern in which the peak coincides with the front of the ingrowing pollen tube tips. This wave of ACC-synthase expression can also be induced by incongruous pollination and (partially) by wounding. This indicates that wounding-like features of pollen tube invasion might be part of the stimuli evoking the postpollination response and that these stimuli are interpreted differently by the regulatory mechanisms of the ACC-synthase and -oxidase genes.