Gene Pool Classification of Common Bean Landraces from Chile Based on RAPD and Morphological Data

Abstract

Landraces of common bean (Phaseolus vulgaris L.) from Chile are a phenotypically diverse group whose relationship to the two major gene pools (Andean and Mesoamerican) is unclear. The genetic composition of 69 Chilean landraces, 15 commercial cuitivars grown in Chile, and 11 previously characterized check accessions was examined using RAPDs (random amplified polymorphic DNA). The 25 primers used generated 106 polymorphic bands. A genetic distance (GD) matrix based on simple matching of RAPD phenotypes was converted to a two dimensional plot using multidimensional scaling (MDS). Two major clusters, encompassing most of the accessions, were apparent on the resulting plot and were identified with the Andean and the Mesoamerican gene pools. No obvious signs of introgression or hybridization between gene pools were observed. Clustering analysis using bootstrap samples of the RAPD bands showed that as few as 20 randomly chosen bands could classify the accessions into the correct gene pools nearly as well as all 106 bands. In general, the Andean landraces were collected at more northerly latitudes and higher altitudes than the Mesoamerican landraces. Morphological data were collected for 63 landraces for seven numerical traits and 13 categorical traits. The morphological data used were to create a distance matrix and analyzed as with the RAPD data, but no clear separation of the groups was seen. Accessions from the two groups identified by RAPDs differed significantly for 11 of the 20 traits examined. It was concluded that by RAPDs, the Chilean landraces could be readily classified into the Andean and Mesoamerican gene pools. Morphological traits were less effective at classification.

Diversidade genética em cultivares locais e comerciais de feijão baseada em marcadores RAPD

“…Nienhuis et al (1995) demonstraram em feijão que, com número de bandas igual ou superior a 100, o coeficiente de variação das distâncias genéticas entre os genótipos estabiliza. De forma mais drástica, Johns et al (1997) A variabilidade genética dentro de cada um dos grupos (andino e mesoamericano) é relativamente restrita. Os genótipos do grupo andino apresentaram similaridade superior a 75% e os do grupo mesoamericano, similaridade superior a 65%, quando considerada a cultivar 25 BRM, e superior a 82% entre as outras 28 cultivares incluídas neste grupo (Figura 1).…”

“…Recentemente, diversos autores Vasconcelos et al, 1996;Johns et al, 1997;Cattan-Toupance et al, 1998;Vera et al, 1999;Beebe et al, 2000;Eichenberg et al, 2000) têm demonstrado que marcadores RAPD são capazes de separar genótipos de feijão de acordo com o centro de domesticação.…”

Microsatellite characterization of Andean races of common bean (Phaseolus vulgaris L.)

“…Three of the between genotypes from the southern range of wild and cultivated common beans in the Andes and would provide a possible explanation for the origin of the race from wild beans that do exist in Argentina but that do not exist in Chile (Santalla et al 2004). This point is important given the lack of evidence for a separate domestication leading to race Chile and the incongruence that this race may have arisen separately even though it has not been associated with specific wild accessions (Debouck et al 1993;Johns et al 1997;Chacón et al 2005). Our results may indicate that race Chile precursors moved from the primary center of origin in Northwestern Argentina across the Andes mountains into temperate latitudes in central Chile, a hypothesis that would be supported by results from Sonnante et al (1994) showing close relationship of race Chile genotypes with Argentine wild accessions.…”

“…This was the case for Johns et al (1997) who tried to distinguish the Chile race using RAPDs, Duarte et al (1999) who attempted to differentiate various races with RAPDs and F o r P e e r R e v i e w Beebe et al (2001) who used AFLPs to characterize wild and cultivated Andean beans but could only distinguish wild accessions not cultivars. The conclusions of these three studies predict that there is less diversity among Andean cultivars than in Mesoamerican cultivars and that compared to wild accessions the cultivated Andean gene pool underwent a reduction in diversity, however none of the studies could define race structure at the molecular level or define how this structure would agree with the morphological classification made by Singh et al (1991a, b).…”

Phenotypic diversity in cold-tolerant peanut (Arachis hypogaea L.) germplasm

“…The diversity index was calculated by averaging all the differences in the phenotypic values for each trait divided by its respective range (Johns et al 1997).…”