The south of Colombia is a center of diversity for diploid potatoes in the Solanum tuberosum group Phureja. This germplasm is important for genetic studies and is used as a genetic resource in potato breeding programs. In Andean countries, Phureja group potatoes are a staple food and represent important incomes for smallholder farmers. We studied the genetic diversity and population structure of 110 diploid potato group Phureja accessions by analyzing allele frequencies using a set of 42 microsatellites (simple sequence repeats). The accessions used in this study were 97 diploid S. tuberosum Phureja group accessions from the Colombian Core Collection and 13 diploid accessions from the German germplasm bank. Allelic richness, heterozygosity, population differentiation (F statistics) and population allocation by means of Bayesian modeling analyses were performed. Results indicated that the population is highly diverse (Hs = 0.55), and genetic differentiation (FST = 0.09636) is mainly due to differences between accessions (FIS = 0.17115). These indexes of population differentiation suggest a moderate division within the population but not a marked population structure. Results with respect to the genetic structure of the analyzed germplasm provide the basis for the development and implementation of linkage and association mapping as well as methods for precision breeding such as the search for diagnostic molecular markers.

No abstract

BackgroundPotato frying color is an agronomic trait influenced by the sugar content of tubers. The candidate gene approach was employed to elucidate the molecular basis of this trait in Solanum tuberosum Group Phureja, which is mainly diploid and represents an important genetic resource for potato breeding. The objective of this research was to identify novel genetic variants related with frying quality in loci with key functions in carbohydrate metabolism, with the purpose of discovering genetic variability useful in breeding programs. Therefore, an association analysis was implemented with 109 SNP markers identified in ten candidate genes.ResultsThe analyses revealed four associations in the locus InvGE coding for an apoplastic invertase and one association in the locus SssI coding for a soluble starch synthase. The SNPs SssI-C 45711901 T and InvGE-C 2475454 T were associated with sucrose content and frying color, respectively, and were not found previously in tetraploid genotypes. The rare haplotype InvGE-A 2475187 C 2475295 A 2475344 was associated with higher fructose contents. Our study allowed a more detailed analysis of the sequence variation of exon 3 from InvGE, which was not possible in previous studies because of the high frequency of insertion-deletion polymorphisms in tetraploid potatoes.ConclusionThe association mapping strategy using a candidate gene approach in Group Phureja allowed the identification of novel SNP markers in InvGE and SssI associated with frying color and the tuber sugar content measured by High Performance Liquid Chromatography (HPLC). These novel associations might be useful in potato breeding programs for improving quality traits and to increase crop genetic variability. The results suggest that some genes involved in the natural variation of tuber sugar content and frying color are conserved in both Phureja and tetraploid germplasm. Nevertheless, the associated variants in both types of germplasm were present in different regions of these genes. This study contributes to the understanding of the genetic architecture of tuber sugar contents and frying color at harvest in Group Phureja.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-017-0489-3) contains supplementary material, which is available to authorized users.