Produção Nacional
Revisado por pares
Contrasting rDNA Evolution in Lima Bean (<i>Phaseolus lunatus </i>L.) and Common Bean (<i>P. vulgaris</i> L., Fabaceae)
2010; Karger Publishers; Volume: 132; Issue: 3 Linguagem: Inglês
10.1159/000321677
ISSN1424-8581
AutoresCícero Almeida, Andrea Pedrosa‐Harand,
Tópico(s)Legume Nitrogen Fixing Symbiosis
Resumo<i>Phaseolus vulgaris</i> has two 5S rDNA sites in chromosomes 6 and 10 and from two up to nine 45S rDNA sites depending on the accession. The presence of three 45S rDNA sites, in chromosomes 6, 9 and 10, is considered the ancestral state for the species. For <i>P. lunatus</i>, only one 5S and one 45S rDNA sites in distinct chromosomes were known. In order to investigate the homeologies among these rDNA-bearing chromosomes and the stability of the rDNA sites in <i>P. lunatus</i>, rDNA and <i>P. vulgaris</i> chromosome-specific probes were hybridized in situ to <i>P. lunatus</i>. The chromosomes bearing the 5S and the 45S rDNA of <i>P. lunatus</i> are homeologous to chromosomes 10 and 6 of <i>P. vulgaris</i>, respectively. In contrast to the common bean, no variation in the number of rDNA loci was detected, except for a duplication of the 5S rDNA in the same chromosome in a small group of cultivars. These results suggest that the 5S rDNA site in chromosome 10 and the 45S rDNA site in chromosome 6 represent the ancestral loci in the genus. The 5S rDNA site in chromosome 10 of <i>P. vulgaris</i> is located in the long arm, while in <i>P. lunatus</i> it is present in the short arm, suggesting the occurrence of a transposition or a pericentric inversion after separation of both lineages.
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