Genetic relationships of Arachis (Fabaceae) accessions based on microsatellite markers

The genus Arachis is endemic to South America and contains 83 described species assembled into nine taxonomical sections. The section Arachis is of particular interest because it includes the cultivated peanut (A. hypogaea) and its closely related wild species. In this study, we used 26 microsatellite markers to analyze the genetic variability and relationships of some recently collected germplasm accessions of species in the Arachis section, with emphasis on the B genome species. The knowledge of the genetic relationships among species and accessions is necessary for a more efficient management of germplasm collections and use of wild species for crop improvement. This is especially important for the B genome species, as only one accession of A. ipaensis, the B genome donor to the allotetraploid A. hypogaea (AABB), is available in germplasm collections worldwide. The results shed more light on the genetic relationships between accessions of A. ipaensis, A. gregoryi, A. magna, A. valida and A. williamsii, what expands the number of accessions for incorporation of useful genes from the species associated with the peanut B genome. The analyses also showed a generally high level of intraspecific genetic variability, but usually grouped the accessions according to their genome types and species. However, accessions of some species did not group as expected, and these results suggest the need of further taxonomic revision of a few taxa, especially some accessions of A. gregoryi, A. magna and A. kuhlmannii and the circumscriptions of sections Erectoides and Procumbentes.

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China Summary: This study analyzed the genetic variability and relationships of germplasm accessions of species in the Arachis section, with emphasis on the B genome species, using microsatellite markers. The results provide valuable information for the management and use of wild species in crop improvement. They also suggest the need for further taxonomic revision of certain taxa and sections in the Arachis genus.