Comparison of CMA-karyotypes in three Dendrobium spp

Abstract

Three orchid species, namely Dendrobium moschatum Sw., D. aphyllum Roxb. and D. aggregatum Roxb, were investigated by classical cytogenetics and CMA fluorescent banding methods. Dendrobium moschatum was found to possess 2n=40 chromosomes whereas, In=38 chromosomes found in D. aphyllum and D. aggregatum. The centromeric formula was 34 m+6 sm in D. moschatum, 38 m in D. aphyllum and 32m+6sm in D. aggregatum. No gradual decrease of chromosomal length was observed in these species indicated as primitive type. The total length of In chromosome complements in D. moschatum was 55.74μm and 59.94μm in D. aphyllum. Total length was remarkably less in D. aggregatum (44.15μm). A pair of bright CMA bands was found in the interphase nuclei of these 3 species. In metaphase stage, 6 CMA bands were found in D. moschatum. The number of CMA bands was 4 and 10 in D. aphyllum and D. aggregatum, respectively. The percentage of CMA banded region in D. aphyllum was 4.76% while it was about double in D. moschatum (11.33%) and 3 times in D. aggregatum (15.38%). The CMA karyotypic features suggested that number, distribution and location of CMA bands were found to be speciesspecific. © 2010 The Japan Mendel Society.