中华水韭雌配子体及胚胎发育的初步研究

Preliminary Study on the Megagametophyte and Embryological Development of Isoetes sinensis

中华水韭(Isoetes sinensis Palmer)属水韭科(Isoetaceae)草本拟蕨类,是长江中下游特有的古老物种,对环境污染敏感,为国家一级重点保护的极度濒危的野生植物。本研究通过人工培养,按不同发育阶段,用常规石蜡切片法连续观察了雌配子体及胚胎发育的全过程。结果显示:大孢子培养15～20 d萌发,雌配子体为球状、属壁内发育型,每个雌配子体着生8～20个颈卵器。成熟的颈卵器发育有多种可能,但只有颈沟细胞和腹沟细胞都退化,卵才有受精的机会。合子首先进行横向分裂,培养约50 d发育成数十个细胞的球形胚胎,约80 d雌配子体的细胞萎缩,第一叶及其叶舌、第一根结构更明显,出现第二叶。文中还初步探讨了中华水韭濒危的生殖生物学机制。

Isoetes sinensis Palmer belongs to Isoetaceae,it＇s an herbaceous fern-ally and an old endemic species from middle and downside of the Yangtze River. It is extremely sensitive to environmental pollution,and falls under national level protection of extreme endangered wild plants. The gametophytes of Isoetes sinensis were cultivated artificially. We observed the development process of megagametophytes and embryos based on different developmental stages,using paraffin section. Results show that the megaspore germinated when fostered for 15-20 days. The megagametophytes were spherical and belonged to intramural development type. Between 8 to 20 archegonia formed in each megagametophyte. The development of mature archegonia had many possibilities. Only neck canal cells and ventral canal cells degenerated,and eggs had the chance to fertilize. The zygote first proceeded to transverse division,and then developed into dozens of spherical embryo cells when fostered for about 50 days. After 80 days the megagametophyte cells become atrophied,the structure of the first leaf,ligule and first root were more obvious,and the second leaf also appeared. This paper discusses preliminary research on the reproductive biology mechanism of endangered Isoetes sinensis Palmer.