云贵水韭雌配子体发育及其濒危机制的研究

Female Gametophyte Development and Endangered Mechanism Research in Isoetes yunguiensis

为了解云贵水韭(Isoetes yunguiensis)的生殖过程和濒危原因,采用人工培养获得其雌配子体,用半薄切片法观察雌配子体发育过程。结果表明,云贵水韭的大孢子萌发率约为26%;雌配子体异养,终生都在大孢子细胞壁内发育;颈卵器发育只有2枚颈沟细胞而无腹沟细胞。雌配子体发育停止在游离核时期、颈壁细胞数量偏少或排列紊乱、颈沟细胞异常、卵细胞凋亡等可能是导致生殖濒危的原因。同时,游离核是水韭生殖生物学研究和系统学研究的重要环节之一;缺失腹沟细胞可能是水韭类简化性进化的特征之一。

In order to understand the reproductive process and endangered reason of Isoetes yunguiensis, its female gametophytes were obtained by artifi cial culture, the development of female gametophyte was observed by using semithin section technology. The results showed that the germination rate of megaspore was 26%. The female gametophyte was heterotrophic, and developed in megaspore wall throughout its lifetime. There were only two neck canal cells and no ventral canal cell in archegonium development of I. yunguiensis. The main reasons led to reproductive endanger could be female gametophyte development stop in free nuclear stage, less neck wall cell or arranged disorders, neck canal cell abnormal, apoptosis of egg, and so on. Meanwhile, free nuclear is one of important steps in reproductive biology and systematics study of Isoetes. The missing ventral canal cell might be a characteristic of simplicity evolution of Isoetes.