Summary Although Crinum pratense and C. defixum have similar karyomorphology i.e. 2n=22 chromosomes, diffuse type of interphase nuclei and continuous type of prophase chromosomes when stained with orcein, yet a major variation, such as two CMA-positive bands in C. pratense and one in C. defixum at mataphase were found. The CMA-positive bands in both the species were found in interphase and as well as prophase. The GC-rich repetitive sequences seemed to keep their domain intact throughout the cell cycle. During counter staining with DAPI, the CMA-positive portions showed DAPI-negative bands. Reversible banding indicated that the amount of GC-rich bases was more abundant in the former species. Moreover, DAPI-positive bands appeared at the centromeric regions of 18 out of 22 chromosomes in C. pratense which were totally absent in C. defixum. It showed the AT-rich nature of C. pratense chromosome complements. Two species had different isozyme activity. Activities of esterase and acid phosphatase were higher in C. defixum. Thus the two species showed distinct variations in their fluorescent karyotypes and activities of isozymes. These features support their different species rank.The genus Crinum L. belongs to the family Amaryllidaceae. Two different species of Crinum, C. pratense and C. defixum are found to grow generally in the hilly areas as well as in the plains of north-eastern part of Bangladesh. Their morphological variations are not sufficient to distinguish them as separate species. Moreover, orcein stained karyotype analysis failed to show remarkable variation among them (Alam et al. 1991). Therefore, it is necessary to study their karyotypes by using reversible fluorescent banding techniques along with some other parameters.Materials and methods C. pratense and C. defixum were collected from Sylhet and Gazipur Districts, respectively and maintained in the Botanical Garden, Department of Botany, University of Dhaka, Bangladesh.The karyotypes of these two species were prepared by using chromomycin A3 (CMA) and 4-6'-diamidino-2-phenyl indole (DAPI). These were compared with their conventional karyotypes. Moreover, resting nuclei and prophase chromosomes stained with both orcein and fluorochromes were analysed. In addition to these isozyme studies following polyacrylamide gel electrophoresis (PAGE), were also done. For fluorescent banding, Alam and Kondo's (1995) method was used. Following PAGE isozyme activity on the gels were detected according to the methods of Aiirs and Orton (1983).
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