A novel locus for extreme resistance to Potato virus Y (PVY), Ry-f sto , was identified on potato chromosome XII. The gene Ry-f sto has been introgressed from the wild potato species Solanum stoloniferum. Inheritance of Ry-f sto in the tetraploid potato population Rysto was consistent with the model of a single, dominant gene. Bulked segregant analysis identified an ISSR (inter-simple sequence repeat) marker UBC 857 980 linked to Ry-f sto . This marker mapped to linkage group XII of a reference potato RFLP (restriction fragment length polymorphism) map. Chromosome XII specific RFLP markers were converted into PCRbased STS and CAPS markers and tested for linkage with Ry-f sto in the population Rysto. CAPS marker GP122 718 was tightly linked to the resistance gene and was successfully used to identify Polish and German cultivars expressing extreme resistance to PVY. This indicates that the source of Ry-f sto has been widely utilized in various potato breeding programs and can be monitored by a diagnostic marker in markerassisted selection.

Globodera rostochiensis and Globodera pallida are parasitic root cyst nematodes of potato (PCN), which significantly reduce yield and quality. The genetics and available molecular markers should make resistance to nematodes an excellent candidate for marker assisted selection. The study presents results of testing the suitability of known molecular markers for detection of resistance in a set of cultivars. We revealed some inconsistencies in genealogical data of the cultivars and showed inconsistent usefulness in detecting resistant cultivars. The marker TG689 was identified in almost all cultivars resistant to G. rostochiensis and together with other markers was used for verifying the resistance in a group of breeding lines. The marker TG689 was the most effective. However, the efficiency of tested markers in selecting resistant individuals might be inadequate. In the case of quantitative resistance to G. pallida, marker SPUD1636 was found in resistant cultivars, and not in susceptible cultivars, but turned out to be inefficient in selecting resistant breeding lines.Resumen Globodera rostochiensis y Globodera pallida son nematodos de quiste parásitos de la raíz de la papa (PCN) que reducen significativamente el rendimiento y la calidad. La genética y los marcadores moleculares disponibles, deberían de hacer de la resistencia a nematodos un excelente candidato para selección asistida con marcadores. El estudio presenta resultados de probar lo deseable de los marcadores moleculares conocidos para la detección de resistencia en un grupo de variedades. Revelamos algunas inconsistencias en datos genealógicos de las variedades y mostramos uso inconsistente en la detección de variedades resistentes. El marcador TG689 se identificó en casi todas las variedades resistentes a G. rostochiensis y junto con otros marcadores se usó para verificar la resistencia en un grupo de líneas de mejoramiento. El marcador TG689 fue el más efectivo. No obstante, podría ser inadecuada la eficiencia de los marcadores probados en la selección de individuos resistentes. En el caso de resistencia cuantitativa a G. pallida, se encontró el marcador SPUD1636 en variedades resistentes y no en los susceptibles, pero resultó ser ineficiente en la selección de líneas de mejoramiento resistentes.

The two most important bacterial diseases of cultivated potato, blackleg of stems and tuber soft rot, are caused by Erwinia species. Genetic resistance currently present in cultivars is insufficient to protect the crop. New sources of polygenic resistance to Erwinia carotovora ssp. atroseptica (van Hall) Dye (Eca) have been selected in diploid hybrids originating from intercrossing Solanum tuberosum L with the wild species S. chacoense Bitter and S. yungasense Hawk. One F1 hybrid population derived from these materials was used to locate, on the molecular map of potato, quantitative trait loci (QTL) for resistance of tubers and leaves to Eca. A linkage map was constructed based on AFLP and RFLP markers including three resistance‐gene‐like (RGL) markers. Clustering of AFLP markers in putative centromeric regions was observed. QTL analysis revealed complex inheritance of resistance to Eca. Genetic factors affecting resistance to Eca were located on all 12 potato chromosomes. Putative QTL for tuber resistance were identified on 10 chromosomes. The QTL with the largest and most reproducible effect on tuber resistance mapped to chromosome I. Effects on leaf resistance were less reproducible than effects on tuber resistance. Putative QTL for leaf resistance were identified on 10 chromosomes. Inheritance of tuber and leaf resistance to Eca was largely independent. Several QTL for resistance to Eca were linked to RGL loci. Four of those QTL mapped to genomic segments that have been shown to contain factors for qualitative and quantitative resistance to different pathogens in potato, tomato (Lycopersicon esculentum Mill.), or tobacco (Nicotiana tabacum L.).

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Key message Sen2 gene for potato wart resistance, located on chromosome XI in a locus distinct from Sen1 , provides resistance against eight wart pathotypes, including the virulent ones important in Europe. AbstractSynchytrium endobioticum causes potato wart disease imposing severe losses in potato production, and as a quarantine pathogen in many countries, it results in lost trade markets and land for potato cultivation. The resistance to S. endobioticum pathotype 1(D1) is widespread in potato cultivars but new virulent pathotypes appear and the problem re-emerges. To characterize and map a new gene for resistance to potato wart, we used diploid F1 potato population from a cross of potato clone resistant to S. endobioticum pathotype 1(D1) and virulent pathotypes: 2(G1), 6(O1), 8(F1), 18(T1), 2(Ch1), 3(M1) and 39(P1) with a potato clone resistant to pathotype 1(D1) only. The 176 progeny clones were tested for resistance to eight wart pathotypes with a modified Glynne–Lemmerzahl method. Bimodal distributions and co-segregation of resistance in the population show that a single resistance gene, Sen2, underlies the resistance to eight pathotypes. Resistance to pathotype 1(D1) was additionally conferred by the locus Sen1 inherited from both parents. Sen2 was mapped to chromosome XI using DArTseq markers. The genetic and physical distances between Sen1 and Sen2 loci were indirectly estimated at 63 cM and 32 Mbp, respectively. We developed PCR markers co-segregating with the Sen2 locus that can be applied in marker-assisted selection of potatoes resistant to eight important pathotypes of S. endobioticum. Wide spectrum of the Sen2 resistance may be an indication of durability which can be enhanced by the pyramiding of the Sen2 and Sen1 loci as in 61 clones selected within this study.Electronic supplementary materialThe online version of this article (10.1007/s00122-018-3154-y) contains supplementary material, which is available to authorized users.