Abstract
Key message Sen2gene for potato wart resistance, located on chromosome XI in a locus distinct fromSen1, provides resistance against eight wart pathotypes, including the virulent ones important in Europe.Synchytrium 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.
Highlights
Synchytrium endobioticum (Schilberszky) Percival is the causal agent of potato (Solanum tuberosum L.) wart disease
A majority of observed variation of resistance was explained by the plant genotype, as coefficients of determination R2 ascribed to this factor ranged from 0.96 to 0.99 depending on pathotype of S. endobioticum used in resistance tests
The same progeny clones were resistant to all virulent pathotypes of S. endobioticum, and there were no clones of intermediate resistance
Summary
Synchytrium endobioticum (Schilberszky) Percival is the causal agent of potato (Solanum tuberosum L.) wart disease. The pathogen originates from the Andean region of South. The presence of potato wart has been reported in Asia, Africa, Europe, Oceania, North America and South America (Baayen et al 2006; Obidiegwu et al 2014). S. endobioticum is considered the most important quarantine pathogen of potato in almost all countries where potatoes are grown. It causes serious yield losses as well as a long-term soil contamination, since the winter sporangia are able to survive in the soil more than four decades (Przetakiewicz 2015a). The disease can be restricted only by quarantine and phytosanitary measures and cultivation of resistant cultivars (Ballvora et al 2011)
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