Karyotype analysis and physical mapping of 18S-5.8S-25S and 5S ribosomal RNA loci in species of genus Lens Miller (Fabaceae)

Abstract

The present study on five different species of genus Lens was conducted to prepare the standard karyotypes integrating the 18S-5.8S-25S and 5S rRNA loci using fluorescence in situ hybridisation and computer aided chromosome image analysis. The results revealed that the five species share different karyotypes with minor modifications, possibly as a result of chromosomal interchanges involving exchanges of chromosomal fragments of nearly similar size during the course of evolution of the genus Lens. In each of the five species, a single locus for 18S-5.8S-25S rRNA on a single pair of chromosomes and two loci for 5S rRNA, possibly representing two different repeat units of varying sizes, on two different pairs of chromosomes were mapped. The rRNA loci were localized at different chromosomal positions in different species and could be used as landmarks for chromosome identification. The idiograms based on measurements on chromosomes and the data on physical mapping of rRNA loci allowed clear distinction of the karyotypes of all the five species, which were hitherto considered to be similar. © 2002 Taylor & Francis Group, LLC.