Mode of pollen-tube growth in Pistils of Myrica rubra (Myricaceae): a comparison with related families.
Mode of pollen-tube growth in Pistils of Myrica rubra (Myricaceae): a comparison with related families.
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DOI：
10.1093/aob/mcj015
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发表时间：
2006
期刊：
影响因子：
4.2
通讯作者：
A. Sogo;H. Tobe
中科院分区：
文献类型：
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作者：
A. Sogo;H. Tobe
背景与目的众所周知，在Fagales中，授粉后受精延迟数周以上。最近的研究表明，在此期间，花粉管在雌蕊中的生长与胚珠的发育密切相关，木麻黄属(木麻黄属)的花粉管发育经历了五步过程，桦木属植物则经历了四步过程。花粉管的数量从多个减少到一个，这一事实表明延迟受精在配子体选择中发挥了作用。杨梅(杨梅科)也表现出授粉后2周的延迟受精，但不知道在此期间雌蕊中的花粉管是如何生长的。方法用荧光显微镜和扫描电子显微镜观察雌蕊花粉管的生长和胚珠的发育，并对雌蕊切片进行分析。结果红花牡丹雌蕊中花粉管生长的发育研究表明，花粉管顶端在子房室上部空间或珠被顶端附近分枝或呈之字形排列，珠心表面随后膨大。这样的形态变化表明，受精前花粉管的生长暂时停止。因此，红花牡丹的花粉管生长可概括为三个阶段：(1)从柱头到子房室；(2)从子房室到珠心表面；(3)从珠心表面到胚囊。结论杨梅与其他科不同，花粉管在珠心表面停止生长，可能消化珠心细胞中的营养物质。关于费加莱斯的其他五个家族的信息很少。为了更好地了解该目内花粉管生长方式的多样性和功能，需要进行广泛的研究。
BACKGROUND AND AIMS It is generally known that fertilization is delayed for more than a few weeks after pollination in Fagales. Recent studies showed that, during that period, pollen tubes grew in pistils in close association with the development of the ovule in a five-step process in Casuarina (Casuarinaceae) and a four-step process in Alnus (Betulaceae). The number of pollen tubes was reduced from many to one, a fact suggesting that delayed fertilization plays a role for gametophyte selection. Myrica (Myricaceae) also shows delayed fertilization for >2 weeks after pollination, but nothing is known of how pollen tubes grow in the pistil during that period. METHODS Pollen-tube growth and the development of the ovule in pistils was investigated by fluorescent and scanning electron microscopy and analysis of microtome sections of the pistils. KEY RESULTS Developmental study of the pollen-tube growth in the pistil of M. rubra showed that the tip of the pollen tube was branched or lay in a zigzag pattern in the upper space of the ovarian locule or near the tip of the integument, and subsequently was swollen on the nucellar surface. Such morphological changes indicate that the pollen-tube growth was temporarily arrested before fertilization. The pollen-tube growth in M. rubra can therefore be summarized as occurring in three steps: (1) from the stigma to the ovarian locule; (2) from the ovarian locule to the nucellar surface; and (3) from the nucellar surface to the embryo sac. CONCLUSION Myrica differs from other families in that the pollen tubes arrest their growth on the nucellar surface, probably digesting nutrient from nucellar cells. There is little information on five other families of Fagales. An extensive study is needed to better understand the diversity and function of the mode of pollen-tube growth within the order.