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Comparative C-banding and Fluorescent-banding Analysis of Seven Species of Drosera (Droseraceae).

1996; International Society of Cytology; Volume: 61; Issue: 4 Linguagem: Inglês

10.1508/cytologia.61.383

1348-7019

Shamimul Alam Sheikh, Katsuhiko Kondo,

Chromosomal and Genetic Variations

Approximately 60 species (about 2/3rd) of the Drosera L. are endemic to Australia in different climatic zones.The discovery of new Drosera species is still going on (Kondo 1984, Lowrie 1994).A series of aneuploid chromosome numbers were reported in Australian Drosera species with a basic chromosome numbers of X = 6, 7, 8, 9, 10, 11, 13 and 14 (Kondo 1976, Kondo et al. 1976, Kondo and Oliver 1979).Moreover, the diffuse centromeric nature of the chromosomes made the genus more interesting among the Drosera cytogeneticists.Kondo and Lavarack (1984) demonstrated that the variation in chromosome number and morphology of Australian Drosera species could be correlated with different geographical distribution, population, habit and habitat.As a result of the apparent explosive speciation in Drosera in Australia, species are often difficult to discriminate morphologically (Marchant and Lowrie 1992).It is well known that if morphological data are meagre, cytological studies may provide more informations to solve the taxonomic problems.Thus, an attempt was undertaken to clarify the relationships among the Australian Drosera species using karyomorphological data (Kondo 1976, Kondo et al. 1976 , Kondo and Oliver 1979).However, only conventional karyotypic study would not be able to provide sufficient informations especially in the case of closely related species and taxa .Giemsa C-banding (Sarker and Datta 1987, Zheng et al. 1991) and DNA base specific fluorescent banding (Schweizer 1976, Hizume et al. 1989) have been used in different plant materials for critical and detailed chromosome analysis.However, such investigations have yet been very much lacking in Drosera species.Thus, it becomes an urgent need to study the differential banding schedules for providing more detailed karyotypic illustrations that would be helpful for unambiguous classification in Australian Drosera species .In this paper we analyzed C-and fluorescent banding karyotypes together with conventional orcein karyotypes of seven species of Australian Drosera . Materials and methodsTable 1 shows the plant materials used in this study.Gemmae or seeds of the seven species were purchased from Australia.Propagation and cultivation of gemmae and seeds were carried out in the greenhouse of the Laboratory of Plant Chromosome and Gene Stock, Faculty of Science Hiroshima University.Some gemmae of D. callistos and seeds of D. petiolaris were surface sterilized and inoculated in hormone free 1/2 Murashige and Skoog (1962) (MS) medium supplemented with 0.2% gellan gum and 3% sucrose for in vitro culture .