Microsatellite variation in maize landraces from Northwestern Argentina: genetic diversity, population structure and racial affliations

Abstract

The highland region or Northwestern Argentina (NWA) is one of the southernmost areas of native maize cultivation and constitutes an expansion of the Peruvian Andes sphere of inXuence. To examine the genetic diversity and racial aYliations of the landraces cultivated in this area, 18 microsatellite markers were used to characterize 147individuals from 6 maize races representative of traditional materials. For the whole data set, a total of 184 alleles were found, with an average of 10.2 alleles per locus. The average gene diversity was 0.571. The observed patterns of genetic diVerentiation suggest that historical association is probably the main factor in shaping population structure for the landraces studied here. In agreement with morphological and cytogenetic data, Bayesian analysis of NWA landraces revealed the occurrence of three main gene pools. Assessment of racial aYliations using a combined dataset including previous data on American landraces showed a clear relationship between one of these gene pools and typical Andean races, whereas the remaining two gene pools exhibited a closer association to Caribbean accessions and native germplasm from the United States, respectively. These results highlight the importance of integrating regional genetic studies if a deeper understanding of maize diversification and dispersal is to be achieved.