THE STRUCTURE AND DEVELOPMENT OF INCOMPLETELY CLOSED CARPELS IN AN APOCARPOUS SPECIES, SAGITTARIA TRIFOLIA (ALISMATACEAE)
THE STRUCTURE AND DEVELOPMENT OF INCOMPLETELY CLOSED CARPELS IN AN APOCARPOUS SPECIES, SAGITTARIA TRIFOLIA (ALISMATACEAE)
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无壳物种慈姑（泽泻科）不完全闭合心皮的结构和发育
DOI：
10.3732/ajb.1400172
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发表时间：
2014-07-01
影响因子：
3
通讯作者：
Wang, Xiao-Fan
中科院分区：
文献类型：
--
作者：
Huang, Lan-Jie;Wang, Xiao-Wen;Wang, Xiao-Fan
研究前提：心皮闭合通常被认为是被子植物的关键创新；然而，一些家庭继续表现出各种形式的心皮不完全闭合。矢车菊的心皮有一种不寻常的结构。本研究确定了三叶草心皮的闭合类型，并对其发育演变进行了探讨。方法：采用扫描电镜和半薄切片光镜观察心皮发育和成熟结构。并对瘦果的花粉管生长和种子萌发进行了研究。关键结果：心皮发育后期，心皮边缘中部发生生殖后融合。成熟期心皮边缘的最下部和最上部保持开放。成熟心皮不完全闭合，有一个充满分泌物的管道，从柱头延伸到心皮基部的开口。在这个位置，花粉管要么长到胚珠上，要么离开心皮，长到其他心皮上。基部开口也作为幼苗出苗的出口点。结论：三叶草心皮闭合不完全不同于以往研究记录的闭合类型，因为心皮内的子房有两个入口与外界环境相连。这种类型的心皮闭合是心皮基部心皮边缘缺乏融合的结果，可以促进三叶草的结实率和幼苗萌发
Premise of the study: Carpel closure is commonly considered as a key innovation in angiosperms; however, some families continue to exhibit a variety of forms of incomplete carpel closure. The carpel of Sagittaria species contains an unusual structure. In this study, we confirm the closure type of the carpel of Sagittaria trifolia and discuss its development and evolution.Methods: Scanning electron microscopy and light microscopy of semithin sections were used to observe the development and the mature structure of the carpel. Pollen tube growth in the carpel and seed germination in the achene was also studied.Key results: During late carpel development, the middle parts of the carpel margins underwent postgenital fusion. However, at maturity the lowest and uppermost parts of the carpel margins remained open. The mature carpel was incompletely closed and contained a secretion-filled canal, which extended from the stigma to the opening at the carpel base. At that site, pollen tubes could either grow to the ovule or exit the carpel and grow to other carpels. The basal opening also served as an exit point for the seedling to emerge.Conclusions: Incomplete carpel closure by S. trifolia differs from the closure types recorded in previous studies because two entrances link the ovary in the carpel to the outside environment. This type of carpel closure occurs as a result of the lack of fusion of the carpel margins at the base of the carpel and could improve the seed set and seedling germination of S. trifolia