The reported narrow genetic base of cultivated potato (Solanum tuberosum) can be expanded by the introgression of many related species with large genetic diversity. The analysis of the genetic structure of a potato population is important to broaden the genetic base of breeding programs by the identification of different genetic pools. A panel composed by 231 diverse genotypes was characterized using single nucleotide polymorphism (SNP) markers of the Illumina Infinium Potato SNP Array V2 to identify population structure and assess genetic diversity using discriminant analysis of principal components (DAPC) and pedigree analysis. Results revealed the presence of five clusters within the populations differentiated principally by ploidy, taxonomy, origin and breeding program. The information obtained in this work could be readily used as a guide for parental introduction in new breeding programs that want to maximize variability by combination of contrasting variability sources such as those presented here.

Potatoes is often considered a drought‐sensitive crop and its sustainable production is threatened due to frequent drought episodes. Drought tolerance is a complex trait of increasing importance in potatoes therefore its yield is threatened. The differential response of several physiological and agronomical traits was evaluated in a diverse potatoes panel under contrasting water regimes to identify quantitative trait loci (QTL) associated with drought tolerance using genome‐wide association analysis with 4859 high‐quality SNP markers. Phenotypic data were collected from multiple environments and years. QTL with diverse linkage disequilibrium blocks for proline concentration, water consumption and yield were detected on chromosomes 1, 4 and 10. These QTL detected were associated with known gene functions. The current study provides insights into the putative genes that controlled the responses to the drought tolerance in potatoes at physiological and agronomical levels. The QTL described in this work might be included in future marker‐assisted selection programmes linked with drought tolerance in potatoes.

BackgroundDiversity in crops is fundamental for plant breeding efforts. An accurate assessment of genetic diversity, using molecular markers, such as single nucleotide polymorphism (SNP), must be able to reveal the structure of the population under study. A characterization of population structure using easy measurable phenotypic traits could be a preliminary and low-cost approach to elucidate the genetic structure of a population. A potato population of 183 genotypes was evaluated using 4859 high-quality SNPs and 19 phenotypic traits commonly recorded in potato breeding programs. A Bayesian approach, Minimum Spanning Tree (MST) and diversity estimator, as well as multivariate analysis based on phenotypic traits, were adopted to assess the population structure.ResultsAnalysis based on molecular markers showed groups linked to the phylogenetic relationship among the germplasm as well as the link with the breeding program that provided the material. Diversity estimators consistently structured the population according to a priori group estimation. The phenotypic traits only discriminated main groups with contrasting characteristics, as different subspecies, ploidy level or membership in a breeding program, but were not able to discriminate within groups. A joint molecular and phenotypic characterization analysis discriminated groups based on phenotypic classification, taxonomic category, provenance source of genotypes and genetic background.ConclusionsThis paper shows the significant level of diversity existing in a parental population of potato as well as the putative phylogenetic relationships among the genotypes. The use of easily measurable phenotypic traits among highly contrasting genotypes could be a reasonable approach to estimate population structure in the initial phases of a potato breeding program.Electronic supplementary materialThe online version of this article (10.1186/s12863-017-0556-9) contains supplementary material, which is available to authorized users.

Water stress is the most significant environmental stress in agriculture worldwide.Potato (Solanum tuberosum L.) is a drought-susceptible crop. Water stress tolerance is a complex trait of increasing importance in potato. The objective of this work was to evaluate the differential response strategies associated with water stress tolerance in a highly diverse potato panel. Multienvironment trials were assessed, both in field and in glasshouse with contrasting water regimes. The yield, dry matter, and frying ability were measured in the field assays, whereas proline concentration (PrC), relative water content (RWC), and water consumption (WC) were measured in the glasshouse assays. A mixed linear model and ANOVA were performed. The best linear unbiased predictors (BLUPs) of every genotype for each measured variable were estimated.Pearson correlation coefficient (r) and principal component analysis (PCA) assessed the association among traits. The genotypes were ranked by their BLUPs values. The high diversity potato panel showed variability both in the response to water stress and within each water regime. In general, Solanum tuberosum spp. andigena genotypes were associated with the lowest PrC and higher yield, WC, and RWC. By using BLUPs, a panel of genotypes with good performance under water deficit was defined. This paper provides knowledge useful to design breeding strategies to water stress tolerance and new physiological research lines. The utilization of the elite genotypes identified in this study as progenitors constitute a starting point for breeding programs oriented to develop water-stress-tolerant varieties.