Background: Arachis hypogaea (peanut) is an important crop worldwide, being mostly used for edible oil production, direct consumption and animal feed. Cultivated peanut is an allotetraploid species with two different genome components, A and B. Genetic linkage maps can greatly assist molecular breeding and genomic studies. However, the development of linkage maps for A. hypogaea is difficult because it has very low levels of polymorphism. This can be overcome by the utilization of wild species of Arachis, which present the A-and Bgenomes in the diploid state, and show high levels of genetic variability.

Background: The genus Arachis includes Arachis hypogaea (cultivated peanut) and wild species that are used in peanut breeding or as forage. Molecular markers have been employed in several studies of this genus, but microsatellite markers have only been used in few investigations. Microsatellites are very informative and are useful to assess genetic variability, analyze mating systems and in genetic mapping. The objectives of this study were to develop A. hypogaea microsatellite loci and to evaluate the transferability of these markers to other Arachis species.

The genus Arachis currently comprises 69 described species, some of which have potential and real value as human and animal foods. These Arachis species have been collected and maintained in germplasm banks to provide material that can be used as sources of genes in breeding programs and for the selection of new cultivars. One of the principal objectives of germplasm conservation is the evaluation of genetic variability, which is best conducted using molecular markers. We investigated the use of heterologous primers to amplify microsatellite loci that could be used to evaluate genetic variability in Arachis germplasm. Fifteen microsatellite primer pairs were tested in 76 accessions of 34 species from the nine Arachis sections. The data indicated that heterologous primers were very useful in Arachis since they had high transferability among the species (91%) and allowed the amplification of very polymorphic putative loci, which allowed both the characterization of most accessions and to make inferences about the mating systems of some species analyzed. Our data also revealed that the germplasm analyzed showed high variability, even when represented by few accessions.