旱生蕨类植物金毛裸蕨配子体发育及其生态意义

摘要

Gametophyte development of a xeric fern was less studied.In present investigation,the gametophyte development of a xeric fern,Gymnopteris vestita was studied using light microscopy.Spores,trilete and brown when matures,germinate at about 10～15 d after sowing.The spore germination pattern is the Vittaria-type.The prothallial cell firstly develops into the uniseriate filaments.And the subsequent development differs greatly from the non-xeric ferns.The most obvious feature of the gametophyte development is producing abundant branches.In most cases,the filaments can produce filamentous branches by longitudinal divisions of the basal cells of the uniseriate filaments.These branches may further branch several times.The terminal end of the branches can form plates.And these plates can also produce filaments or plates.Finally,the gametophytes form cluster colony.In a few cases,the uniseriate filament forms plate directly.However,the plates do not develop into prothallus,but form plenty of filamentous branches.At the cluster stage,numerous antheridia occur in the filaments and surface of the plate.No archegonia are discovered at artificial culture condition.The vegetative growth of the gametophyte last a long time if the culture conditions was suitable.New filaments form continually from the old plates.Apogamous sporophytes are discovered in the large heart-shaped prothallus,which always lie in the outside of the cluster.The features of gametophyte development of G.vestita,including the multi-branched clusters,flourishing vegetative growth of the gametophytes,and apogamy,suggest a xeric adaptation to the reproduction of the ferm G.vestita.%采用光学显微镜对旱生金毛裸蕨(Gymnopteris vestita)配子体发育的全过程进行了观察.结果显示,(1)旱生金毛裸蕨孢子三裂缝,成熟时黄褐色,接种后10～15 d萌发,萌发类型为书带蕨型.原叶体母细胞首先形成单列的丝状体,其后配子体发育明显区别于非旱生的蕨类,金毛裸蕨配子体发育最明显的特征是形成大量的分枝,通常单列的丝状体基部细胞可通过细胞纵分裂形成丝状分枝,这些分枝又可进一步产生新的分枝,分枝的末端可形成片状体,这些片状体又可产生分枝丝状体或片状体,最终整个配子体可发育为群丛.有时,单列的丝状体也可直接发育为片状体,然而这些片状体并不发育为原叶体而是产生大量的丝状分枝.当群丛形成时,在丝状体或片状体表面可产生数量较多的精子器,但在人工培养条件下并没有发现颈卵器.如果培养条件适宜,配子体可进行营养繁殖,持续较长时间,老的片状体上可产生新的丝状体.金毛裸蕨位于群丛外的大型心形原叶体可进行无配子生殖产生孢子体.金毛裸蕨的配子体发育特征,包括多分枝、发达的营养繁殖及无配子生殖现象的发生,表明了金毛裸蕨配子体群丛的形成是对于旱生环境的一种适应性.