Abstract
BackgroundArgentina has a long tradition of sunflower breeding, and its germplasm is a valuable genetic resource worldwide. However, knowledge of the genetic constitution and variability levels of the Argentinean germplasm is still scarce, rendering the global map of cultivated sunflower diversity incomplete. In this study, 42 microsatellite loci and 384 single nucleotide polymorphisms (SNPs) were used to characterize the first association mapping population used for quantitative trait loci mapping in sunflower, along with a selection of allied open-pollinated and composite populations from the germplasm bank of the National Institute of Agricultural Technology of Argentina. The ability of different kinds of markers to assess genetic diversity and population structure was also evaluated.ResultsThe analysis of polymorphism in the set of sunflower accessions studied here showed that both the microsatellites and SNP markers were informative for germplasm characterization, although to different extents. In general, the estimates of genetic variability were moderate. The average genetic diversity, as quantified by the expected heterozygosity, was 0.52 for SSR loci and 0.29 for SNPs. Within SSR markers, those derived from non-coding regions were able to capture higher levels of diversity than EST-SSR. A significant correlation was found between SSR and SNP- based genetic distances among accessions. Bayesian and multivariate methods were used to infer population structure. Evidence for the existence of three different genetic groups was found consistently across data sets (i.e., SSR, SNP and SSR + SNP), with the maintainer/restorer status being the most prevalent characteristic associated with group delimitation.ConclusionThe present study constitutes the first report comparing the performance of SSR and SNP markers for population genetics analysis in cultivated sunflower. We show that the SSR and SNP panels examined here, either used separately or in conjunction, allowed consistent estimations of genetic diversity and population structure in sunflower breeding materials. The generated knowledge about the levels of diversity and population structure of sunflower germplasm is an important contribution to this crop breeding and conservation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0360-x) contains supplementary material, which is available to authorized users.
Highlights
Argentina has a long tradition of sunflower breeding, and its germplasm is a valuable genetic resource worldwide
Within the association mapping population (AMP-IL), 25 alleles were unique to the maintainer (HA) lines, while 16 were private to the restorer (RHA) lines; and 36 alleles were private to the Argentinean germplasm when compared to the “Other origin” germplasm
The inbred lines included in the present work were part of the first association mapping study reported for sunflower [9] and are an essential component of the Instituto Nacional de Tecnología Agropecuaria (INTA) sunflower breeding program, as different complex characters are currently being assessed on these accessions
Summary
Argentina has a long tradition of sunflower breeding, and its germplasm is a valuable genetic resource worldwide. Knowledge of the genetic constitution and variability levels of the Argentinean germplasm is still scarce, rendering the global map of cultivated sunflower diversity incomplete. Macrocarpus) is one of the most important oilseed crops, with a cultivated area of 25 million hectares worldwide The history of introduction and adaptation of sunflower in Argentina is closely related to that of the human migration flows. The introduction of early materials from Russia, Canada and Romania, as well as the introgression with wild Helianthus species allowed the emergence of the Argentinean germplasm, which has a distinct genetic constitution and is well adapted to local growing conditions [2,3]. The introduction of heterosis, first described in 1966 [4], the incorporation of cytoplasmic male sterility after interspecific crossing with H. petiolaris Nutt [5], and the development of fertility restorer lines by Kinman in 1970 [6] allowed practical development of sunflower hybrids, with higher yield and quality potential, high homogeneity, maturing time synchronicity and better adaptation to field applications [7]
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