Jarosław Plich, Jarosław Przetakiewicz, Jadwiga Śliwka, Bogdan Flis,  Iwona Wasilewicz-Flis,  Ewa Zimnoch-Guzowska

Theoretical and Applied Genetics; November 2018, Volume 131, Issue 11, pp 2321–2331

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.

Abstract

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.

See: https://link.springer.com/article/10.1007/s00122-018-3154-y

Figure 3: Positions of loci Sen1 and Sen2 for S. endobioticum resistance on the simplified genetic maps of chromosome XI developed using diploid F1 potato population SEN 12-01. Only five markers per map are shown, and the remaining ones are listed in the Online Resource 3. a Joined map (P1 + P2) of chromosome XI showing the position of Sen2, constructed of 273 markers, using 176 individuals and a maximum likelihood algorithm. b Joined map (P1 + P2) of chromosome XI showing the position of Sen1, constructed of 150 markers, using 96 individuals, regression mapping and Haldane’s mapping function. Maps were constructed using JoinMap^® 4.1 (Van Oojien 2006). Genetic distances (cM) on the left and marker/loci names on the right of the chromosome representations