Comparative study of the generic and chromosomal variation using RAPD marker method

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Brachyscome Cass comprises about 80 species and occurs in a diversity of habitats from the rainfall zones to the arid regions of Australia. This genus shows extraordinary chromosomal versatility, involving structural changes and variation in number from n=2 to 15 as well as intraspecific polyploidy and thus offers excellent opportunities to examine chromosomal evolution from the structural changes in genes or other DNA molecules. We analyzed generic differences among species which have different chromosome numbers, n=9,4,3, but closely related each other, using polymerase chain reaction method.1. In the RAPD marker analyzes, we could not detected species specific band patterns. Band patterns of the taxa having n=9 were conservative, while those with n=3 and 4 showed significant variation even within the same species.2. In the analyzes of the adh gene polymorphism, species with n=9 had a signal PCR products. While taxa with n=3 and 4 had three or more PCR products which contained inserted elements in the intron sequence.It is interesting that the species with n=9 are conservative both chromosomal and molecular levels in comparison with those of species with the advanced chromosome number. Genomic reorganization has occurred not only at the chromosomal levels but also at the molecular ones in the advanced annual species with small chromosome number.