Identification of Molecular Markers Linked to Resistance to Different Pathotypes of Synchytrium endobioticum in a Dihaploid Potato Population

The obligate biotrophic, soil-borne fungus Synchytrium endobioticum is the causal agent of potato wart disease. The quarantine pathogen infects tubers, stolons and stems of the potato, causing yield losses of up to 50-100 %. Typical symptoms are the formation of cauliflower-like irregular galls on the below-ground parts of the plant. In Europe, 38 different pathotypes of Synchytrium endobioticum have been reported, with pathotypes 1, 2, 6 and 18 being the most relevant and aggressive forms. Common strategies to control the disease are strict phytosanitary measures and breeding of resistant cultivars. As the phenotypic evaluation of resistance to Synchytrium endobioticum is very laborious and often ambigiuous, DNA-based markers closely linked to wart resistance genes would considerably facilitate the detection of resistance to potato wart disease.

To reduce genome complexity a dihaploid potato population was generated from a highly resistant tetraploid potato cultivar through a so-called prickle pollination to facilitate molecular marker analyses. In a Bulked Segregant Analysis approach, Simple Sequence Repeat- and Single Strand Conformation Polymorphism-markers were identified that are significantly associated with resistance to different pathotypes of Synchytrium endobioticum. The identified markers were developed from resistance gene analogs in the Sen1-region on potato chromosome 11. In a genome wide SNP genotyping approach using the 12.8k SolCAP SNP genotyping array, SNP markers were identified that were also significantly linked with resistance and were also located on chromosome 11, indicating that Sen1 is the major locus conferring resistance to various pathotypes of Synchytrium endobioticum.