Karyotype stability in the genus Phaseolus evidenced by the comparative mapping of the wild species Phaseolus microcarpus
Abstract:The genus Phaseolus L. (Fabaceae) is monophyletic and comprises approximately 75 species distributed into two principal clades. The five cultivated species, including the common bean (Phaseolus vulgaris), were placed in clade B. Clade A comprises only wild species, with more limited distribution. In the present work, bacterial artificial chromosomes (BACs) previously mapped in common bean (2n = 22) were used as probes in fluorescent in situ hybridization (FISH) in this comparative study of Phaseolus microcarpus (2n = 22), a species from clade A. We also analyzed the chromomycin A3 (CMA)/4′,6-diamidino-2-phenylindole (DAPI) banding pattern and the localization of rDNA and telomeric DNA sites. The single 45S rDNA site from P. microcarpus was mapped to chromosome 6, showing conservation to the P. vulgaris homeolog. Of the two 5S rDNA sites identified in both species, only the site on chromosome 10 appeared conserved. In spite of the phylogenetic distance between the two species, all of the single-copy BACs demonstrated conservation of synteny. However, four collinearity breaks were observed, probably caused by para- and pericentric inversions. Some variation in the repetitive fraction of the genome was also observed. Thus, a broader analysis of the genus confirms that few, rare inversions seem to represent the main karyotype changes during the evolution of this genus.
Keywords: bacterial artificial chromosome; cartographie comparée; chromosome bactérien artificiel; comparative mapping; fluorescent in situ hybridization; hybridation in situ en fluorescence; interstitial telomeric sequence; repetitive DNA sequences; séquence télomérique interstitielle; séquences répétitives d’ADN
Document Type: Research Article
Publication date: January 1, 2013
- From its inception in 1957, this international cytogenetics journal has catered to the research areas of the members of the Genetics Society of Canada; traditionally, these have included agriculture, entomology, genetics/cytogenetics, and evolutionary mechanisms. The contents of the journal have evolved as contributors developed new technologies and interests. A 20-member Editorial Board is composed of scientists from around the world. Reviews and commentary from respected experts are often featured.
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