ABSTRACT. Analysis of DNA polymorphisms allows for the genetic identification and precise discrimination of species with a narrow genetic base such as common bean. The primary objectives of the present study were to molecularly characterize commercial common bean varieties developed at various research institutions using microsatellite markers and to determine the degree of genetic diversity among the bean varieties analyzed. Fifty cultivars representing 12 grain classes and 64 genitors, i.e., accessions used to develop these cultivars, were characterized. Based on an analysis of 24 simple sequence repeats, the estimates for the average number of alleles and genetic diversity were 8.29 and 0.646, respectively. The combined probability of identity was estimated at 7.05 x 10 -17 , indicating a high individual discriminatory power. Thirtytwo percent of the cultivars exhibited heterogeneity for multiple loci that reflected either homozygosity for different alleles of a given locus in different individuals or heterozygosity for the locus. The average 1964-1978 (2014) Molecular characterization of cultivated common bean genetic diversity for the groups of cultivars and genitors was 0.605 and 0.660, respectively, with no genetic differentiation (F ST ) between these groups. Although similar estimates of expected heterozygosity were observed when the cultivars were grouped by release date, a greater number of private alleles was observed in the most recent cultivars. The genetic differentiation among cultivars originating from different institutions was not different from zero (F ST = 0.01). The molecular profile database derived from these analyses may increase the statistical power of genetic estimates and may be incorporated into breeding programs for common bean. Furthermore, the profiles obtained for the different cultivars may be used as molecular descriptors to complement traditional descriptors used in distinctiveness, uniformity and stability tests, thereby improving the traceability of samples and their derivatives and helping to protect the intellectual property rights of breeders.

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ABSTRACT. The identification of germplasm genetic variability in breeding programs of the common bean (Phaseolus vulgaris) is essential for determining the potential of each combination of parent plants to obtain superior genotypes. The present study aimed to estimate the extent of genetic diversity in 172 lines and cultivars of the common bean by integrating five tests of value for cultivation and use (VCU) that were conducted over the last eight years by the breeding program of Embrapa Arroz e Feijão in Brazil. Nine multilocus genotyping systems composed of 36 fluorescent microsatellite markers distributed across 11 different chromosomes of the common bean were used, of which 24 were polymorphic. One hundred and eighty-seven alleles were identified, with an average of 7.79 alleles per locus and an average gene diversity of 0.65. The combined probability of identity for all loci was 1.32 x 10 between the selection cycles were identified, allowing the breeding program to develop a crossbreed between elite genotypes with a low degree of genetic relatedness. H E values (ranging from 0.31 to 0.63) and the genetic differentiation among the VCU tests (F ST of 0.159) supports for new strategies to increase the genetic base from which the program is conducted. Private alleles (26%) were identified and can be directly incorporated into the gene pool of cultivated germplasm, thereby contributing effectively to the expansion of genetic diversity in this bean-breeding program.