Evidence for utility of the same PCR‐based markers for selection of extreme resistance to Potato virus Y controlled by Rysto of Solanum stoloniferum derived from different sources

Abstract

AbstractThe tuber‐bearing wild potato species, Solanum stoloniferum, carries a dominant gene, Rysto, which confers extreme resistance (ER) to Potato virus Y (PVY). This gene was introgressed to cultivated potato germplasm (Solanum tuberosum) using accessions of S. stoloniferum maintained in European gene banks. It is mainly used in potato breeding programmes in Europe. Rysto was recently mapped to potato chromosome XII. However, in this study, a different accession of S. stoloniferum (PI275244; Haw1293) was used as a female parent in a cross to obtain a diploid (2n = 2x = 24) potato population of 112 F1 genotypes. From this accession, ER to PVY has been introgressed to the potato breeding programmes at the International Potato Center (Peru). As expected, ER to PVY was inherited in a dominant, monogenic fashion in the F1 population. Marker‐specific choices of DNA polymerase and adjustments of PCR conditions were made to optimise marker detection. The corresponding gene (Rysto) was mapped to the chromosome XII using the previously described and new cleaved amplified polymorphic sequence (CAPS) markers, which are based on the restriction fragment length polymorphism loci GP122 (six markers) and GP269 (one marker), and the simple sequence repeat marker STM0003. Four GP122‐based CAPS markers and STM0003 detected the same genotypes expressing ER to PVY. Because of a few recombinants, that is ER genotypes lacking the markers and the genotypes that react with necrosis but contain the markers, the marker distance from Rysto was estimated as 15.2 cM in this F1 population. However, the distance may be less if necrosis was considered an altered response also controlled by Rysto. The markers also specifically detected independent European potato cultivars that express ER to PVY derived from S. stoloniferum. Phylogenetic analysis of the sequences amplified from the GP122 locus of S. stoloniferum and potato cultivars further confirmed that the Rysto gene from independent accessions of S. stoloniferum can be selected using the same markers and the protocols described in this study.