Cytological Studies On Liverworts From China

Bryophytes are the special group of higher plants on the transition from aquicolous to terraneous life style. The gametophytes (haploid) of bryophytes are dominant to the life cycle. Chromosomes are the carrier of gene. Chromosome number and karyotype are the ground work of taxonomy, cytology and genetics. Cytological studies on bryophytes can provide the informative data for systematics and cytology, and can reveal the karyological variability in this large group. Moreover, karyological data also can give basal evidence when we discuss the taxonomic and phylogenic problems of bryophytes. The cytological studis of bryophytes are difficult because most bryophytes are very small without active mitosis in meristematic tissue of a root and the chromosome character of centromere and secondary constriction are unclear. Many basic problems are still unkown for the cytology of bryophytes. Untill now, only 10 % of 23,000 species of bryophytes over the world are counted the chromosome numbers. China, with 1,200 liverworts and about 100 endemic species, is one of the countries with most diversity of bryophytes. Up to the present, only 157 species, including 51 liverworts and 106 mosses, were examined chromosome numbers. It accounts for only 4.7% of all the known bryophytes of China. Therefore, cytological studies of Chinese liverworts are very urgent.During Dec. 2003-Feb. 2007, liverworts samples were collected from Bawaling Nature Reserve and Diaoluoshan Nature Reserve of Hainan province, Maoershan Nature Reserve of Guangxi province, Tianmushan Nature Reserve and Shengzhou of Zhejiang province, Taibaishan Nature Reserve of Shaanxi province and Singapore. This paper deals with chromosome numbers of 121 species of liverworts (115 species from China and 10 from Singapore). The chromosome numbers of 57 species are reported for the first time. Out of 48 genera studied here, six genera have never been studied cytologicaly, including Notoscyphus, Colura, Lepidolejeunea, Schiffneriolejeunea, Podomitrium, and Tuyamaella. Karyotypes of 47 species are analysed by means of the karyotype formula. Stebbins karyotype and coefficient of karyotypic overall asymmetry, which are usually used in vascular plants, are applied in bryophytes for the first time and their referential value in karyological study of bryophyte is discussed, too.The studies on chromosome numbers of 121 liverworts species showed that the chromosome numbers of liverworts are relatively conservative, most of them have n=8, 9 or 10. Chromosome numbers of n=8, 9 and 10 are found in all thalloid liverworts. In leafy liverworts only two species show n=10. The chromosome numbers of most leafy liverworts are n=8 or n=9. At the same time some species were found with two different chromosome numbers owing to polyploidy and aneuploidy. The relationship between its morphology and polyploidy or aneuploidy in liverworts needs further study.Length of each members of chromosomes of 121 species is measured. By comparing the length of chromosomes of different groups in liverworts, a phylogenic relationship of liverworts was analysed and the result is correspond to the phylogenic tree, which is based on the updated molecular evidence. The author found that the size of chromosomes becomes to be smaller when the evolutional level rises just as the other higher plants. The variability of length of different groups may be related to the evolutional level and phylogenic ship of different groups.The results of karyotype formula, centromere, the ratio of the largest chromosome to the smallest chromosome (Lt/St), Stebbins karyotype and coefficient of karyotypic overall asymmetry of 47 liverwort species revealed that liverworts have rich diversity of the karyology. In liverworts, the karyological variability increases when the length of the chromosome becomes small.In addition, the author made a database of chromosome counts of bryphytes from all over the world for the first time, based on all published literature. This database can provide an international window for cytological studies of bryophytes and make good effect in the Chinese bryology.The following 57 species are reported chromosome numbers for the first time:1. Acrolejeunea fertilis (Reinw. et al.) Schiffn. n=82. Archilejeunea amakawana Inoue n=83. Archilejeunea polymorpha (Sande Lac.) B.M. Thiers & Gradst. n=94. Caudalejeunea recurvistipula (Gottsche) Schiffn. n=95. Cephaloziella spinicaulis Douin n=96. Cheilolejeunea ceylanica (Gottsche) R.M. Schust. & Kachroo. n=87. Cheilolejeunea intertexta (Lindenb.) Steph. n=88. Cheilolejeunea meyeniana (Gottsche et al.) R.M. Schust. & Kachroo n=89. Cheilolejeunea osumiensis (S.Hatt.) Mizut. n=810. Cheilolejeunea trifaria (Reinw.et al) Mizut. n=811. Cheilolejeunea verrucosa Steph. n=812. Chiloscyphus muricatus (Lehm.) J. J.Engel & R.M.Schust. n=9 13. Cololejeunea cf. macounii (Spruce) A.Evans n=814. Cololejeunea ocellata (Horik.) Benedix n=815. Cololejeunea ocelloides (Horik.) Mizut. n=816. Colura inuii Horik. n=817. Colura tenuicornis (A.Evans) Steph. n=918. Drepanolejeunea thwaitesiana (Mitt.) Steph. n=819. Frullania davurica Hampe n=920. Frullania fengyangshanensis R.L.Zhu & M.L.So n= ♀ 9, ♂821. Heteroscyphus zollingeri (Gottsche) Schiffn. n=10+m22. Jungermannia truncata Nees n=923. Lejeunea sordida (Nees) Nees n=9+m24. Lejeunea subacuta Mitt. n=8, n=925. Lepidolejeunea bidentula (Steph.) R.M.Schust. n=926. Leucolejeunea paroica N.Kitag. n=827. Leucolejeunea turgida (Mitt.) Verd. n=928. Lopholejeunea eulopha (Taylor) Schiffn. n=9 39. Lopholejeunea soae R.L.Zhu & Gradst. n=830. Lopholejeunea subfusca (Nees) Schiffn. n=831. Marsupella commutata (Limpr.) Bernet n=932. Metzgeria consanguinea Schiffn. n=833. Notoscyphus lutescens (Lehm.) Mitt. n=934. Nowellia aciliata (P.C.Chen & P.C.Wu) Mizut. n=935. Plagiochila fordiana Steph. n=8+m36. Plagiochila gracilis Lindenb. & Gottsche n=8+m37. Plagiochila peculiaris Schiffn n=8+m38. Plagiochila salacensis Gottsche n=8+m39. Plagiochila wightii Nees ex Lindenb. n=940. Pleurozia subinflata (Austin) Austin n=8+m41. Podomitrium malaccense (Steph.) Campb. n=942. Porella campylophylla (Lehm. & Lindenb.) Trevis. n=843. Radula acuminata Steph. n=844. Radula acuta Mitt. n=845. Radula amoena Herzog n=8 46. Radula anceps Sande Lac. n=847. Radula cavifolia Hampe ex Gottsche et al. n=848. Radula formosa (Meissn.) Nees n=849. Radula gedena Gottsche ex Steph. n=850. Radula inouei K.Yamada n=851. Radula onraedtii K.Yamada n=852. Radula philippinensis K.Yamada n=853. Riccardia elata (Steph.) Schiffn. n=9+m54. Riccardia graeffei (Steph.) Hewson n=9+m55. Riccardia kodame Mizut. & S.Hatt. n=9+m56. Schiffneriolejeunea tumida (Nees & Mont.) Gradst. var. haskarliana (Gottsche) Gradst.& Terken n=857. Tuyamaella molischii (Schiffn.) S.Hatt. n=9, n=8...