濒危植物水松小孢子发生和雄配子体发育的研究

水松(Glyptostrobus pensilis)是我国特有的单种属孑遗植物,是极度濒危物种,被列为国家一级重点保护植物。为了从生殖生物学方面探讨水松的濒危机制,采用石蜡切片法对水松小孢子发生及雄配子体发育过程进行了系统地观察研究。结果表明:水松雄球花于10月中旬开始分化,11月初小孢子囊壁形成,12月初小孢子母细胞形成,12月中旬减数分裂。翌年1月中旬形成四面体形和左右对称形四分体,1月下旬四分体解体,释放出游离小孢子。2月中旬花粉粒发育成熟,并以二细胞形态进行传粉,散粉期约为2周左右。3月萌发花粉管,3月下旬出现精原细胞、管核和不育核,5月下旬花粉管到达颈卵器顶部,精原细胞分裂成两个精细胞。水松小孢子和雄配子体发育过程中败育和变形现象很少,据此我们认为,水松小孢子发生与雄配子体发育正常,不是致其濒危的主要原因。

Studies on Microsporogenesis and Development of Male Gametophytes in Endangered Species Glyptostrobus pensilis

Glyptostrobus pensilis is an endemic and First Grade critically endangered species in China. To research the reproductive biology of G. pensilis in relation to its influence on the endangered status, microsporogenesis and development of male gametophytes were observed using paraffin wax sections. The results were as follows： The male cone differentiated in mid-October, and the microsporangium wall, which was composed of the epidermis, a middle layer and a tapetum, occurred in early November. The microspore mother cells formed at the beginning of December, and meiosis of the microsporocyte occurred in mid-December. The tetrads were formed as isobilateral and tetrahedron forms in mid-January of the following year, and the microspore tetrads eventually separated and the microspores were released in late January. Pollen matured in mid-February and were shed in the form of two cells over two weeks. After pollen shedding, the pollen tube was produced in March, and the spermatogonia, tube nuclei and sterile nuclei occurred in late March. The pollen tube contacted the top of archegonium, and the spermatogonium then divided into two sperm waiting for insemination in late May. Deformation and abortion were observed in the process of microsporogenesis and the development of male gametophytes, whose percentage was low. There was no influence on normal pollen shedding. Microsporogenesis and development of male gametophytes, which were normal, were not the main factorinfluencing the endangerment of G. pensilis.