Identification of essentially derived soybean cultivars using microsatellite markers

Abstract

Soybean [Glycine max (L.) Merrill] is an annual herbaceous leguminous crop, with a high grain protein content and easy adaptation to diverse soil-climatic conditions. It is one of the main oil crops of the world, actually the most cultivated. This leguminous plant accounts for approximately 44% of the Brazilian agricultural production destined for exportation and is the crop that earns most foreign exchange for the country. In 2004, Brazil accounted for about 25% of the world’s soybean production (Conab 2005). In spite of the great number of commercial soybean varieties in Brazil, the genetic variability between them is minor, mainly because they were derived from the same set of some few ancestors (Hiromoto and Vello 1986, Abdelnoor et al. 1995). ABSTRACT Cultivars within a species are traditionally distinguished by morphological traits. In some species such as soybean however, varieties are generally obtained from very similar elite parent groups, which makes the morphological differentiation rather difficult. The aim of this study was to differentiate two soybean varieties by means of microsatellite markers. One variety was susceptible and the other resistant to soybean stem canker, the latter essentially derived from the former, in five backcross generations. The DNA used in the analysis was obtained from morphologically indistinguishable seed of the two varieties studied. Forty-two microsatellite loci distributed across the integrated genetic map of soybean were analyzed, of which one locus, Satt115, differentiated the two varieties, indicating that even essentially derived varieties can be discriminated by molecular markers.