Differential Fluorescent Chromosome Banding of Solanum nigrum L. and Solanum villosum L. from Bangladesh

Abstract

Two species of the genus Solanum viz. S. nigrum and S. villosum found in Bangladesh were cytogenetically investigated to confirm their taxonomic status. S. nigrum and S. villosum were found to possess 2n=24 and 2n=48 chromosomes, respectively. The centromeric formula 22m+2sm was found in S. nigrum and 48m in S. villosum. No gradual decrease of chromosomal length was observed in both the species indicated their karyotypes as primitive type. The individual chromosomal length ranged from 1.66 to 2.34 μm in S. nigrum and 1.66 to 2.66 μm in S. villosum. The total chromatin length in S. villosum (97.8 μm) was almost double to that of S. nigrum (48.94 μm). The range of relative length of chromosomes was similar in these two species. Solanum nigrum and S. villosum possessed 18 and 17 CMA positive bands, respectively. Most of the CMA-bands were present at the terminal region in both the species. The percentage of CMA banded region in S. villosum (35.43) was almost double to that of S. nigrum (18.69). A pair of DAPI positive bands was found on both the end of all the chromosomes in these 2 species. Each band was 0.5 μm in length. The karyotype of S. nigrum studied here indicated that the specimen was not actually S. nigrum rather it has much simillarities with S. americanum. Solanum villosum showed regular bivalent formation at metaphase-I and segregation at anaphase-I. The overall karyotypic features suggested S. villosum as an ancient auto-tetraploid of S. americanum which in course of time has started regular meiosis.