【摘要】 用电镜揭示了小叶满江红(Azolla microphylla)的大孢子果萌发与成苗期间满江红鱼腥藻(Anabaena azollae)孢子与宿主建立共生关系的过程。发现大部分藻孢子首先与幼孢子苗发生的多细胞腺毛结合,之后进入第一片真叶叶腔,并继续按照同样的方式被转移到相继形成的真叶叶腔或分支茎尖。萌发的鱼腥藻孢子只在孢子苗的茎尖区域或叶腔中观察到,其萌发模式与自生鱼腥藻相似。92％萌发的满江红鱼腥藻孢子附着或靠近腺毛。这些腺毛呈现出分泌型传递细胞的结构特征。由此推测藻孢子从腺毛获得某种刺激萌发的化学信息或促进细胞增殖的营养物质。藻孢子萌发形成的营养细胞在叶腔中分化出固氮的异形胞,从而开始了新的共生世代。更多还原

【Abstract】 The process of establishing symbiotic relationship of Anabaena azollae with its host during the megaspore germination and sporeling development was examined using electron microscope. The observations revealed that most of the Anabaena spores were primarily adhered to the hair cells arisen from the sporeling subsequently introduced into the cavity of the 1st true leaf by the hair cells. Following the sporeling development, the Anabaena spores were migrated to the newly developing cavities and the branch apex in the same way. The pattern of germination of the Anabaena spore is similar to that of free-living cyanobacteria. Germinating Anabaena spores were only found at shoot apex region and the cavities of the sporeling, 92% of them being onto or near the hair cells which exhibit the ultrastructural characteristics of the transfer cell. The results suggested that Anabaena spore might get the chemical signal stimulating germina- tion or the substance supporting cell multiplication from the host. Some of vegetative cells. derived from the Anabaena spore were differentiated in to nitrogen-fixing heterocysts within the cavity. This means that the new generation of the symbiosis between Anabaena and Azolla has begun.更多还原