Differential staining with orcein, Giemsa, CMA, and DAPI for comparative chromosome study of 12 species of Australian Drosera (Droseraceae)
1995
Sheikh, S.A. | Kondo, K.
Differential stainings with orcein, Giemsa, CMA, and DAPI were compared in 12 species of Western Australian Drosera. Chromosome numbers of D. roseana, D. barbigera, D. leioblasta, D. oreopodion, D. mannii, D. walyunga, D. sewelliae, D. helodes, and D. echinoblasta are reported here for the first time. A marked difference regarding chromosome number was observed in Drosera dichrosepala (2n = 12) from that of the previous report (2n = 18). The karyotypes of the species showed commonly that degree of asymmetry in chromosome length was directly proportional to the mean chromosomal length whereas the number of chromosomes was inversely proportional. Bimodal karyotypes were observed in D. oreopodion, D. walyunga, D. barbigera, and D. echinoblasta, which perhaps resulted from interspecific hybridization of the former two and fragmentation in the latter two. Sat-chromosomes found in D. falconeri, D. sewelliae, D. helodes, and D. echinoblasta responded differently in differential staining. The C and fluorescent bands at the mostly terminal region revealed that maximum C-positive heterochromatin-rich segments, GC-rich segments, and AT-rich segments were accumulated at the ends of Drosera chromosomes. Some chromosomes could be identified by their specific staining property. On the basis of chromosome number and C- and fluorescent-banding pattern, we suggest that D. helodes and D. sewelliae are closely related.
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