title: Microsatellite diversity and genetic structure among common bean (Phaseolus vulgaris L.) landraces in Brazil, a secondary center of diversity.
abstract: Brazil is the largest producer and consumer of common bean (Phaseolus vulgaris L.), which is the most important source of human dietary protein in that country. This study assessed the genetic diversity and the structure of a sample of 279 geo-referenced common bean landraces from Brazil, using molecular markers. Sixty-seven microsatellite markers spread over the 11 linkage groups of the common bean genome, as well as Phaseolin, PvTFL1y, APA and four SCAR markers were used. As expected, the sample showed lower genetic diversity compared to the diversity in the primary center of diversification. Andean and Mesoamerican gene pools were both present but the latter gene pool was four times more frequent than the former. The two gene pools could be clearly distinguished; limited admixture was observed between these groups. The Mesoamerican group consisted of two sub-populations, with a high level of admixture between them leading to a large proportion of stabilized hybrids not observed in the centers of domestication. Thus, Brazil can be considered a secondary center of diversification of common bean. A high degree of genome-wide multilocus associations even among unlinked loci was observed, confirming the high level of structure in the sample and suggesting that association mapping should be conducted in separate Andean and Mesoamerican Brazilian samples.
authors.affiliation: Section of Crop and Ecosystem Sciences, Department of Plant Sciences/MS1, University of California, Davis, CA 95616-8780, USA.
authors.forename: Marília Lobo
authors.initials: ML
authors.lastname: Burle
authors.forename: Jaime Roberto
authors.initials: JR
authors.lastname: Fonseca
authors.forename: James A
authors.initials: JA
authors.lastname: Kami
authors.forename: Paul
authors.initials: P
authors.lastname: Gepts
mesh_terms: D001938:Brazil; D002874:Chromosome Mapping; D005788:Gene Pool; D056426:Genetic Loci / Q000235:genetics; D005819:Genetic Markers; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics; D005843:Geography; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats / Q000235:genetics*; D008957:Models, Genetic; D027805:Phaseolus / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic
chemical_list: D005819:Genetic Markers