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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >Anatomy of ovary and ovule in dandelions (Taraxacum, Asteraceae)
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Anatomy of ovary and ovule in dandelions (Taraxacum, Asteraceae)

机译：蒲公英（蒲公英，菊科）的卵巢和胚珠的解剖

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The genus Taraxacum Wigg. (Asteraceae) forms a polyploid complex within which there are strong links between the ploidy level and the mode of reproduction. Diploids are obligate sexual, whereas polyploids are usually apomictic. The paper reports on a comparative study of the ovary and especially the ovule anatomy in the diploid dandelion T. linearisquameum and the triploid T. gentile. Observations with light and electron microscopy revealed no essential differences in the anatomy of both the ovary and ovule in the examined species. Dandelion ovules are anatropous, unitegmic and tenuinucellate. In both sexual and apomictic species, a zonal differentiation of the integument is characteristic of the ovule. In the integumentary layers situated next to the endothelium, the cell walls are extremely thick and PAS positive. Data obtained from TEM indicate that these special walls have an open spongy structure and their cytoplasm shows evidence of gradual degeneration. Increased deposition of wall material in the integumentary cells surrounding the endothelium takes place especially around the chalazal pole of the embryo sac as well as around the central cell. In contrast, the integumentary cells surrounding the micropylar region have thin walls and exhibit a high metabolic activity. The role of the thick-walled integumentary layers in the dandelion ovule is discussed. We also consider whether this may be a feature of taxonomic importance.
机译：蒲公英属Wigg。 （菊科）形成多倍体复合体，其中倍性水平与繁殖方式之间有很强的联系。二倍体是专性的，而多倍体通常是无融合生殖的。该论文报道了对二倍体蒲公英线虫和三倍体T. gentile的卵巢，尤其是胚珠解剖学的比较研究。用光学和电子显微镜观察发现，在所检查的物种中，卵巢和胚珠的解剖结构没有本质差异。蒲公英的胚珠是倒卵，单卵和腱生。在有性和无融合生殖的物种中，珠被的区域性分化都是胚珠的特征。在靠近内皮的皮层中，细胞壁非常厚并且PAS呈阳性。从TEM获得的数据表明这些特殊的壁具有开放的海绵状结构，并且它们的细胞质显示出逐渐退化的证据。壁材料在内皮周围的被膜细胞中的沉积增加，尤其是在胚囊的查拉兹极周围以及中央细胞周围。相反，围绕小孔区域的珠被细胞具有薄的壁并表现出高的代谢活性。讨论了厚壁外皮层在蒲公英胚珠中的作用。我们还考虑这是否可能是分类学重要性的特征。

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