Li Yuan-Yuan, Chen Xiao-Mei, Guo Shun-Xing, Lee Yung-I
Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, People's Republic of China.
Biology Department, National Museum of Natural Science, No 1, Kuan-Chien Rd, Taichung, 40453, Taiwan.
Bot Stud. 2016 Dec;57(1):18. doi: 10.1186/s40529-016-0137-7. Epub 2016 Aug 8.
Gastrodia elata, a famous herbal medicine, has been received great attention on its treatments of headache, vertigo and epilepsy. Gastrodia nantoensis is a newly described species from central Taiwan with potential medicinal value. Gastrodia species are fully mycoheterotrophic orchids, and the courses of their seed development are more rapid as compared to the chlorophyllous orchids. A better understanding of their reproductive biology would provide insights into the propagation and conservation of the mycoheterotrophic orchid species.
Based on the histological and histochemical investigations, we observed some notable features in ovule and embryo development. First, only the archesporial cell and/or megasporocyte are present within their ovaries at the time of anthesis. Second, their suspensors consist of a single cell and their mature embryos consist of a gradient of small to large cells. Nile red staining of a globular embryo reveals the presence of cuticular material in the surface wall of embryo proper and the lateral walls of suspensor cell, indicating that the basal wall of suspensor cell is the major route for nutrient supply from maternal tissues to embryo proper. Third, their seed coats are derived from a single integument, and lignin but not cuticular material is present in the outer most layer of seed coat and persists through seed maturation.
The faster seed development of Gastrodia species is due to the speedy courses of ovule and embryo development. In the mature seeds, the presence of a differentiated apical zone in embryo proper suggests the easy-to-germinate character. This study provides basic knowledge for further molecular studies on embryo development and symbiotic germination of Gastrodia species.
天麻是一种著名的草药，在治疗头痛、眩晕和癫痫方面受到了极大关注。南投天麻是一种新描述的来自台湾中部的物种，具有潜在药用价值。天麻属植物是完全的菌根异养兰花，与有叶绿素的兰花相比，它们种子发育过程更快。更好地了解其生殖生物学将为菌根异养兰花物种的繁殖和保护提供见解。
基于组织学和组织化学研究，我们在胚珠和胚胎发育中观察到一些显著特征。首先，花期时其卵巢内仅存在孢原细胞和/或大孢子母细胞。其次，它们的胚柄由单个细胞组成，成熟胚胎由小到大的细胞梯度组成。球形胚的尼罗红染色显示胚体表面壁和胚柄细胞侧壁存在角质物质，表明胚柄细胞的基壁是母体组织向胚体营养供应的主要途径。第三，它们的种皮由单层珠被发育而来，种皮最外层存在木质素而非角质物质，并在种子成熟过程中持续存在。
天麻属植物种子发育较快是由于胚珠和胚胎发育过程迅速。在成熟种子中，胚体中分化的顶端区域的存在表明其易于萌发的特性。本研究为天麻属植物胚胎发育和共生萌发的进一步分子研究提供了基础知识。
