Karyotype Analysis of Three Corchorus Species.

Abstract

The fluorescent banded somatic karyotypes of Corchorus capsularis, C. olitorius and C. trilocularis showed 14 more or less equal sized metacentric chromosomes each. The orcein stained interphase nuclei revealed the presence of a big nucleolus surrounded by a clear non-staining zone. Moreover, the nucleoli were associated with a pair of prominent dots. All of these characteristics make their interphase nucleus unique. Only 2 CMA-stained satellites were found in the interphase, prophase, prometaphase and metaphase plates of these 3 species. These bands indicate the presence of stable GC-rich sequences at the satellited region of these species. The size of satellites and the length of the satellited chromosomes were found nearly same in these species. Two chromosomes of C. capsularis, however, contained one interstitial CMA-positive band in each. The 2 satellited chromosomes of C. capsularis, C. olitorius and C. trilocularis had 2 DAPI-negative bands at the satellited regions. One interstitial DAPI-positive band was found in C. capsularis. These chromosomes could easily be identified with CMA and DAPI. The base specific banding similarity of their chromosome suggests that their genomes may derive from a common ancestor.