Contrasting evolution of a satellite DNA and its ancestral IGS rDNA in Phaseolus (Fabaceae).

Cícero Almeida, Artur Fonsêca, Karla Galvão Bezerra dos Santos, Magdalena Mosiolek, Andrea Pedrosa-Harand

Laboratory of Plant Cytogenetics and Molecular Biology, Department of Botany, Federal University of Pernambuco, Recife, PE, Brazil, 50670-420.

Genome / National Research Council Canada = Génome / Conseil national de recherches Canada 2012 Sep

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CC4 is a satellite DNA from common bean (Phaseolus vulgaris L.) that is similar to its intergenic spacer (IGS) rDNA. CC4 was originally hypothesized to be an old, fast evolving satellite family that has invaded common bean rDNA. To test this hypothesis and contribute to the understanding of IGS-like satellite DNA evolution, we have investigated its distribution in the genus Phaseolus and related species. CC4 was cloned and used as probe for Southern blot and FISH experiments. CC4 was observed as an independent satellite in common bean, forming two to three major and a few minor pericentromeric clusters. In Phaseolus coccineus, CC4 was present in four major clusters, also not co-localized with the 45S rDNA sites. Remarkably, in the less related species of the genus, signals were detected co-localized with the 45S rDNA sites, but co-localization was not observed in the species where CC4 is present as an independent satellite. No signal was detected in species from related genera. Altogether, the data suggest that CC4 has originated from the IGS rDNA in the P. vulgaris-P. coccineus lineage and has evolved slower than the IGS rDNA from this lineage.

Citation

Cícero Almeida, Artur Fonsêca, Karla Galvão Bezerra dos Santos, Magdalena Mosiolek, Andrea Pedrosa-Harand. Contrasting evolution of a satellite DNA and its ancestral IGS rDNA in Phaseolus (Fabaceae). Genome / National Research Council Canada = Génome / Conseil national de recherches Canada. 2012 Sep;55(9):683-9