红盖鳞毛蕨孢子发育的超微结构和细胞化学研究

Ultrastructural and cytochemical studies on spore development in Dryopteris erythrosora(Eaton) O. Ktze.

采用透射电镜和细胞化学技术对红盖鳞毛蕨(Dryopteris erythrosora(Eaton)O.Ktze.)的孢子发育过程进行了研究,根据超微结构和细胞化学特征可将其孢子发育过程分为3个阶段:(1)孢子母细胞及其减数分裂阶段:孢子母细胞壳在孢原细胞末期开始形成,位于孢子母细胞及其减数分裂形成的四分体外侧,PAS反应显示其为多糖性质,与胼胝质壁为同功结构;在减数分裂形成的四分孢子之间产生孢子外壳,从功能、形成位置和时间上看与胼胝质壁相似,但苏丹黑B反应显示其可能含有脂类物质,与孢子母细胞壳和胼胝质壁不同。(2)孢子外壁形成阶段:外壁为乌毛蕨型(Blechnoidal-type),由薄的多糖性质的外壁内层和表面平滑的孢粉素外壁外层构成;小球参与外壁外层的形成,组织化学分析显示小球的中央区域和外壁外层内侧部分由红色(多糖)变为黄色,小球的表面区域和外壁外层部分始终被染成黑色(脂类),可知小球与外壁同步发育。(3)孢子周壁形成阶段:周壁为凹陷型(Cavate-type),包括2层,内层薄,紧贴外壁,外层隆起形成孢子脊状褶皱纹饰的轮廓,以少见的向心方向发育;苏丹黑B和PAS反应观察周壁被染成橙色,推测其可能由多糖等成分构成;孢子囊壁细胞参与周壁的形成。本研究为揭示蕨类植物孢子发生的细胞学机制提供了新资料。

Spore development of Dryopteris erythrosora（ Eaton） O. Ktze. was studied by transmission electron microscopy and cytochemical technology. Based on ultrastructural and cytochemical features,spore development was divided into three stages.（ 1） Spore mother cell and meiosis stage： sporocyte coat is formed at the late stage of the archesporial cells. The sporocyte coat covers the spore mother cells and the outer surface of the tetrads. The PAS reaction shows that this coat is polysaccharide in nature. It is an analogous structure with callose. During meiosis,spore coats are formed between the tetrad spores. The spore coats resemble the callose wall in function,formation site,and formation time. However,Sudan Black B staining shows that the spore coats may contain lipid material,which does not exist in the callose wall.（ 2） Exospore formation stage： exospore formation is Blechnoidal-type. Theexospore consists of two layers,i. e. thin inner exospore and thick outer exospore. The former is composed of polysaccharides and the latter is composed of sporopollenin with a smooth outer surface. Globules participate in the formation of the outer exospore. Cytochemical staining shows that the center of the globules and inner part of the outer layer of the exospore are yellow,but the outer part of the globules and outer layer of the exospore became black when stained（ probably containing lipids）. It can be inferred that the globules and exospore develop simultaneously.（ 3） Perispore formation stage： perispore formation is Cavete-type.The perispore consists of an inner perispore and outer perispore. The thin inner perispore appresses the exospore closely. The outer perispore projects outwards and forms the outline of the ridge ornamentation of the spore. The development of the perispore is centripetal. Sudan Black and PAS reaction stain the perispore orange,indicating that the perispore may be composed of several polysaccharides. Spore wall cells participate in formation of the perispore. The present investigation provides new data for sporogenesis and spore wall development,which will contribute to revealing the cytological mechanism of sporogenesis.