狗脊孢壁发育超微结构的研究

Ultrastructure of the sporoderm development in Woodwardia japonica

关键词:  狗脊  孢壁发育  超微结构

Key words:  Woodwardia japonica  sporoderm development  ultrastructure

摘要:

鳞毛蕨型孢子类型众多,初步研究表明形态相似的孢子类型其孢壁发育特征存在差异,因此有必要对各代表类群的孢壁发育进行深入地研究。该文利用透射电镜对乌毛蕨科(Blechnaceae)狗脊(Woodwardia japonica)孢壁结构和发育的超微结构进行研究。结果表明:(1)狗脊孢子囊的结构由外向内分别为孢子囊壁细胞、两层绒毡层细胞和孢子母细胞;(2)狗脊孢子具乌毛蕨型(Blechnoid type)外壁,表面光滑,由两层构成,裂缝区域具辐射状的槽;(3)周壁属于空心型(cavity type),由四层构成,从内向外分别为P1、P2、P3和P4层,前三层叠合在一起,层间有不同程度的空隙,P4层与前三层之间具有明显而连续的空腔,并隆起形成片状褶皱纹饰;(4)有小球体和小杆共同参与孢子周壁的形成,周壁部分或全部来源于孢子囊壁细胞。综上所述,狗脊孢子与同属于鳞毛蕨型的贯众(Cyrtomium fortunei)和朝鲜介蕨(Dryoathyrium coreanum)孢壁的发育在周壁结构、周壁各层的发育顺序、周壁来源和参与成壁的特征物质等方面存在差异。该研究有利于进一步理解蕨类植物孢壁所蕴含的分类和演化上的科学意义和价值。

Abstract:

There are many subtypes of spore in Dryopteroid type. Preliminary studies show that the characteristics of spore wall development vary even in the similar subtypes in the Dryopteris type. So,it is necessary to study the spore wall development further of the representative species. The development of sporoderm of the fern Woodwardia japonica were studied using transmission electron microscope(TEM)in this study. The results were as followed: The sporangium was composed of sporangial wall cells, two layers of tapetal cells and spore mother cells from outer to the center. The mature spores of W. japonica possess exospored of Blechnoid type with smooth surface. The exspore consisted of two layers and there were radial canals. And the perispore was of cavity type, which consists of 4 layers,i.e. the P1,P2,P3 and P4 from the inner side to the outer side. The inner three layers,i.e. the P1,P2,P3,lied closely and narrow gaps were seen between the three layers. A broad cavity occurs between the P3 layer and P4 layer,which was the outmost layer of the perispore. The perispore forms the plicate lamellate ornamination by local uplift. Spherules and rodlets were observed to participate the perispore formation. All or part of the perispore were derived from the material of the jacket cells of the sporangium. Although the spore type of W. japonica, Cyrtomium fortunei J. Sm.(Dryopteridaceae)and Dryoathyrium coreanum (Christ)Tagawa(Athyriaceae)belonged to the Dryopteroid type,the perispore structure,development of the different layers of the perispore,derivation of the perispore and the characteristic materials that form the perispore of W. japonica spores differed obviously from those of the ferns Cyrtomium fortunei and Dryoathyrium coreanum. The present investigation was beneficial to understand the scientific significance of the spore wall development in classification and phylogeny.