The Ry-fsto gene from Solanum stoloniferum for extreme resistant to Potato virus Y maps to potato chromosome XII and is diagnosed by PCR marker GP122718 in PVY resistant potato cultivars

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 PCR-based STS and CAPS markers and tested for linkage with Ry-f(sto) in the population Rysto. Caps markers 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 marker-assisted selection.