Evidence of gene flow among Argentinean wild beans and landraces using morphoagronomic and molecular data

GALVÁN MARTA; MENÉNDEZ SEVILLANO MARIA; LANTERI ANALÍA; BALATTI PEDRO

ANNUAL REPORT OF THE BEAN IMPROVEMENT COOPERATIVE

Lugar: Michigan; Año: 2007 vol. 50 p. 3 - 4

0084-7747

Argentina is ranked fourth among counties exporting common bean around the world. Beans are cultivated mainly in northwestern Argentina, an area that also represents the southern most limit of the Andean diversification center of the common bean. Based on morphological data the presence of wild-weedy-cultivated complexes was reported in this region (Menéndez Sevillano, 2002; De Ron et al., 2004), suggesting that gene flow is occurring between sympatric populations. Diversity in cultivated beans as revealed by molecular analysis is low (Galván et al., 2001; Galván et al., 2003), therefore it is important to identify sources of diversity, such as wild populations and bean landraces, to use them in breeding programs. The purpose of this work was to characterize wild populations and landraces from Argentina by means of morphoagronomic and molecular data. Ten quantitative traits and ten ISSR primers were assayed among nine wild populations of common bean (Phaseolus vulgaris var aborigineus) and ten landraces from Northern Argentina. Cluster Analysis and Principal Coordinates Analysis of the molecular data grouped wild beans and landraces in two highly similar clusters, also showing a great variability within each cluster (Figure 1). In addition, it was observed a geographical structured genetic variability of wild beans indicated by the Mantel correlation test. On the other hand, genetic variability among landraces suggested homogeneous selection exerted by  farmers in different sites. Wild beans and landraces from one of the sites analyzed (Santa Victoria, Salta; 22°15´S Latitude and 24° 58´W Longitude) showed  high genetic similarity values considering the Jaccard index. One landrace from this site generated unique ISSR patterns and also showed segregation of wild characteristics such as small seeds, dehiscent pods and mottled seed pattern. These results suggested the existence of gene flow between wild and domesticated beans in this area. Therefore, the analysis of the variability and fertility of the hybrids generated would be of a great interest in order to use these beans to introgress characters from wild beans to domesticated cultivars, to broaden the genetic base of commercial beans.