Spore Germination And Development Of 23 Bryophytes

Bryophytes are a lineage of higher plants that propagate by spores.The process from spore germination to protonema development into a mature gametophyte is important evidence for the classification and phylogeny of bryophytes.To reveal spore germination types and development patterns of bryophytes and to obtain a large number of sterile materials are the foundation for genome sequencing and diversity conservation.We observed the spore germination types and development patterns of 23 bryophytes(including two species endemic to China)by the plant tissue culture technology.Eight species,Acanthocoleus yoshinaganus,Ceratolejeunea singapurensis,Diplasiolejeunea rudolphiana,Schiffneriolejeunea tumida,Solenostoma tetragonum,Aitchisoniella himalayensis,Sauteria sp.and Exormotheca bischlerae,are studied for the first time.We confirmed the spore germination types and development patterns of these bryophytes and cultivated enough sterile materials.The results are important evidence for the studies of phylogenetics and diversity conservation of bryophytes.The sterile materials of bryophytes can be used to establish a germplasm resource bank and genome sequence.The main results are as follows:1.The Lejeunea type is known in Acanthocoleus yoshinaganus,Cololejeunea longifolia,C.trichomanis,Colura inuii,Diplasiolejeunea cavifolia,and D.rudolphiana.The Lopholejeunea type occurs in Acrolejeunea sandvicensis,Schiffneriolejeunea tumida,and Spruceanthus semirepandus..The Ceratolejeunea type is known in Ceratolejeunea singapurensis and Lejeunea flava.Cephalozia bicuspidata and Solenostoma tetragonum are of the Cephalozia type.Lophocolea heterophylla is of the Nardia type.Metzgeria furcata is of the Metzgeria type.Aitchisoniella himalayensis is of the Reboulia type,Sauteria sp.is of the Targionia type,Exormotheca bischlerae is of the Stephensoniella type,and Phaeoceros carolinianus is of the exosporous germination pattern.2.In Lejeuneaceae,the same genus has a more similar development pattern in spore germination.Some development patterns of gametophyte structures,such as hyaline papilla,stylus,and rhizoid are the same in this family.3.Hoagland culture medium is suitable for the sexual reproduction of some bryophytes.4.The spore germination time and development into a gametophyte time of three thalloid liverwort are different.Spores of Sauteria sp.and Exormotheca bischlerae germinated within five days,while Aitchisoniella himalayensis within ten days.Sauteria sp.spent forty days developing into gametophyte while E.bischlerae germinated within eighty days.5.The germ rhizoid may be one of the development characteristics of Exormotheca bischlerae rather than abnormal development affected by external factors.6.The spores of three sphagnum species.germinated within eight days and spore germination types are all of the sphagnum type.However,the development time into a gametophyte of these three species are different.Sphagnum acutifolioides only spent 60 days while S.junghuhnianum spent 90 days.All of them produced multicellular filamentous protonema with a large number of chloroplasts,and rhizoid-like structures which have degenerated chloroplasts and oblique transverse walls.The rhizoid-like structure is a kind of protonema,however,no rhizoids were found during the whole development process.