Seed ultrastructure and water absorption pathway of the root-parasitic plant Phelipanche aegyptiaca (Orobanchaceae)
Seed ultrastructure and water absorption pathway of the root-parasitic plant Phelipanche aegyptiaca (Orobanchaceae)
复制标题
DOI：
10.1093/aob/mcr261
复制
发表时间：
2012-01-01
期刊：
影响因子：
4.2
通讯作者：
Welbaum, Gregory E.
中科院分区：
文献类型：
--
作者：
Joel, Daniel M.;Bar, Hilla;Welbaum, Gregory E.
列当科植物的专性根寄生植物只有在化学检测到附近的寄主植物时才会发芽。该家族的成员，如列当、列当和独脚金，是对农业造成严重损害的有毒杂草。尽管它们的经济影响，只有少数的光学显微镜研究他们的微小的种子已经出版，并没有他们的超微结构和每个组织在发芽前的步骤中发挥的作用的知识。本文描述了埃及蒲桃种子的超微结构，有助于我们了解种子组织function.Methods种子进行了检查，在光，扫描电子，透射电子和荧光显微镜下的各种固定和染色协议。结果进行了解释与生理数据的模式吸水和发芽stimulation.Key结果和结论的内皮，这是内层的种皮，迅速吸收水分。其相互连接的细胞充满了粘液，并含有细胞壁，促进水分积累，以便在接受发芽刺激后开始发芽。内皮细胞肿胀导致珠孔开放。在这个开口下面的外胚乳细胞在根际和胚之间起着中介作用，并且可能是萌发刺激的受体的位置。其他外胚乳细胞和胚乳及胚的一部分一样，都含有脂类和蛋白质体。在胚乳中，油体彼此融合，而在胚和外胚乳中它们是完整的。胞间连丝将外胚乳细胞相互连接，珠孔附近的细胞紧紧地包围着萌发的幼苗。这些外胚乳细胞，以及近端胚细胞，具有致密的细胞质内容物，它们似乎代表了在萌发过程中积极参与将储备营养转移到发育中的幼苗的两种种子成分。
Background and Aims Obligate root parasitic plants of the Orobanchaceae do not germinate unless they chemically detect a host plant nearby. Members of this family, like Orobanche, Phelipanche and Striga, are noxious weeds that cause heavy damage to agriculture. In spite of their economic impact, only a few light microscopical studies of their minute seeds have been published, and there is no knowledge of their ultrastructure and of the role each tissue plays during the steps preceding germination. This paper describes the ultrastructure of Phelipanche seeds and contributes to our understanding of seed tissue function.Methods Seeds of P. aegyptiaca were examined under light, scanning electron, transmission electron and fluorescence microscopy following various fixations and staining protocols. The results were interpreted with physiological data regarding mode of water absorption and germination stimulation.Key Results and Conclusions The endothelium, which is the inner layer of the testa, rapidly absorbs water. Its interconnected cells are filled with mucilage and contain labyrinthine walls, facilitating water accumulation for germination that starts after receiving germination stimuli. Swelling of the endothelium leads to opening of the micropyle. The perisperm cells underneath this opening mediate between the rhizosphere and the embryo and are likely to be the location for the receptors of germination stimuli. The other perisperm cells are loaded with lipids and protein bodies, as are the endosperm and parts of the embryo. In the endosperm, the oil bodies fuse with each other while they are intact in the embryo and perisperm. Plasmodesmata connect the perisperm cells to each other, and the cells near the micropyle tightly surround the emerging seedling. These perisperm cells, and also the proximal embryo cells, have dense cytoplasmic contents, and they seem to represent the two seed components that are actively involved in transfer of reserve nutrients to the developing seedling during germination.