极危孑遗物种东方水韭雌配子体及胚胎的解剖学观察

Anatomical Observation on the Female Gametophyte and Embryo of the Critically Endangered Species Isoetes orientalis

以人工培养的国家一级保护植物东方水韭(Isoetes orientalis)为材料,采用切片技术对雌配子体和胚胎的发育进程进行解剖学观察研究,探讨其有性生殖过程及濒危机制。结果表明:(1)东方水韭大孢子3~5d萌发,成熟雌配子体呈球形,无假根,三裂缝处发育出多个颈卵器,成熟颈卵器只有颈壁细胞与颈沟细胞,无腹沟细胞。(2)多数雌配子体只发育出一个胚胎,偶见多胚共存现象;胚胎发育时期,第一叶原基相比第二、三叶原基发育迅速。(3)颈卵器部分组织常出现分化紊乱,导致雌配子体败育。该研究结果支持"根叶理论",并讨论了腹沟细胞的退化以及双胚共存机制,认为东方水韭雌配子体常停留在游离核阶段、颈卵器形态或位置不规则、卵细胞排列紊乱等可能是其败育的原因。

In this paper,the base of nation level protected species Isoetes orientalis is used as materials.With the method of slice technology,we anatomically observed the development process of female gametophytes and embryos,and discussed the reproduction and endangered mechanism.The results showed that：（1）Megaspore of I.orientalis would be germinated within 3-5d,the mature gametophytes were emerging spherical and forming a number of archegonias with triplets but no rhizoids.There were neck cells and neck canal cells in the archegonium,but no ventral canal cells.（2）Most of the female gametophytes were only developed into one embryo,occasionally into more embryos.During the development of embryo,the first primordium growth rapidly than the second and third primordiums.（3）The part tissue of archegonium often appear differentiation disorder and lead to female gametophyte abortion.The results supported the Phyllorhize Theory,also discussed the ventral canal cells degenerated and two embryos mechanism.We speculated that the gametophyte in I.orientalis usually stopped during free nuclei stage,morphology and anomaly site of archegonia and eggs arranged in disorder might be the causes of abortion.