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.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-010-1350-5) contains supplementary material, which is available to authorized users.

Common bean {Phaseotus vulgaris L.) is the most important legume crop for direct human consumption in Brazil. Overall patterns of genetic diversity of common bean in the country are not well understood. Hence, this study sought to integrate morphological and agronomic evaluations with prior molecular diversity data from a geo-referenced collection of Brazilian common bean. Our sample included 279 randomly chosen landrace accessions from the main growing regions of beans in Brazil. Eighteen morphological and three agronomic characters (yield and susceptibility to common bacterial blight and rust diseases) were evaluated in field conditions in Brazil or California. Results show that the sample was diverse morphologically but did not include all the morphological variability described in domesticated common bean outside Brazil. Several accessions showed clear morphological differences in spite of having the same name. The integration of the current morphological and agronomic evaluations with a prior 74-marker diversity assessment of the same landraces improved the identification of five subpopulations identified on the basis of microsatellite diversity. These subpopulations could be distinguished by their morphology, the type and frequency of the market classes they included, and the frequency of susceptibility to diseases. This information will facilitate the management and use of P. vulgaris genetic diversity in Brazil.

Resumo -A coleção de germoplasma de arroz da Embrapa consiste aproximadamente de 10.000 acessos. O objetivo desse trabalho foi estabelecer a Coleção Nuclear (CN) dessa coleção utilizando as informações e dados disponí-veis sobre seus acessos. A estratégia CN foi introduzida no manejo de recursos genéticos vegetais com o principal objetivo de ampliar e sistematizar o uso desses recursos. Uma CN deve ser selecionada procurando reter a variabilidade genética existente na coleção inteira (CI) com um mínimo de redundância. Os acessos da coleção de arroz foram classificados em três estratos: a) variedades tradicionais do Brasil (VT); b) linhagens/ cultivares melhoradas do Brasil (LCM); e c) linhagens/cultivares introduzidas (LCI). As variedades tradicionais foram ainda classificadas segundo o sistema de cultivo (terras altas, várzeas e facultativo). Os três estratos foram representados na Coleção Nuclear, mas ênfase maior foi dada às variedades tradicionais, que constituíram 308 acessos. Os acessos foram alocados para cada sistema de cultivo, proporcionalmente ao produto do logarítmo do número de variedades tradicionais pelo índice de Shannon (medida de diversidade) de cada um deles. A seleção dos acessos foi feita com o auxilio do Sistema de Informação Geográfica (SIG). A CN brasileira de arroz está formada por 550 acessos Termos para indexação: Oryza sativa, SIG, diversidade genética, recursos genéticos, terras altas, várzeas. Constructing a rice core collection for BrazilAbstract -The Rice Germplasm Collection of Embrapa consists of approximately 10,000 accessions. This study aimed to establish a core collection using the currently available information data for those accessions. The strategy Core Collection (CN) was introduced in the management of plant genetic resources with the main purpose of improving the use of these resources. CN should be selected in order to preserve the genetic variability of the whole collection (CI), with minimum redundancy. The accessions within the rice collection were classified into three strata: a) landraces from Brazil (VT); b) breeding materials from Brazil (LCM); and c) introductions (LCI). The landraces were further classified according to crop system (uplands, lowlands and facultative). These three strata were represented in the Core Collection, but more emphasis was considered in representing the landraces, which are represented by 308 accessions. The accessions were allocated, for each crop system, proportionally to the product of the logarithm of the number of landraces by the Shannon Diversity Index (a measure of genetic diversity) within each crop system. Curators and breeders, supported by a Geographical Information System (GIS) made the selection of the accessions. The final Brazilian rice Core Collection consists of 550 accesses.Index terms: Oryza sativa, GIS, genetic diversity, genetic resources, uplands, lowlands. IntroduçãoO arroz (Oryza sativa L.) é cultivado em todos os continentes, sendo um alimento nutritivo na dieta de mais da metade da população mundial. Foi d...

The objective of this study was to characterize for the first time polyphenols and DPPH (2-diphenyl-1-picryhydrazyl radical) antioxidant activity in commonly cultivated accessions