Effect of natural selection on common bean (Phaseolus vulgaris) microsatellite alleles

1Universidade Federal de Lavras, Departamento de Biologia, Lavras, MG, Brazil. The effect of natural selection on microsatellite simple sequence repeat (SSR) alleles was investigated in two distinct common bean (Phaseolus vulgaris) generations (F8 and F24) derived from the cross between the P. vulgaris cultivars Carioca MG x ESAL 686. The F2 segregant population was propagated by the bulk method and 107 plants were sam-pled in two generations (F8 and F24). Each plant generated one family which was replicated by the bulk method to F8:11 and F24:27 families from which DNA was extracted. Thirty pairs of microsatellite primers were polymorphic for the par-ents and the bulk of the F24:27 families. Out of 30 loci selected by natural selection, 29 microsatellite alleles came from the Carioca MG parent and one allele came from the ESAL 686 parent. Natural selection affected all the generations and its intensity was specific for each locus and generation. Therefore all the alleles selected at each locus must be important for adaptation in a breeding program