Resistance to PVM in potato parental lines bred in Młochów Research Center, IHAR.

During last 22 years in the Potato Genetics and Parental Lines Department at Młochów Research Center more than 210 parental lines resistant to Potato virus M (PVM) have been bred. Genes controlling resistance to PVM originated from two sources Solanum megistacrolobum (the gene Rm) or/and S. gourlayi (the gene Gm) were introduced into tetraploid breeding material. From these resistant lines 59 progenitors were chosen and offered to the potato breeders. The first resistant to PVM cultivar Triada and second one cv. Korona were registered in Poland in 1996 and 2002, respectively. At present 13 advanced breeding clones from different breeding stations derived from progenitors offered to breeders in 1986-1990 are evaluated in Preliminary Trials. One candidate cultivar tested in Registration Trials appeared to be resistant to PVM. Moreover 15 advanced breeding clones derived from progenitors offered during 1991-1995 were tested in Preliminary Trials. The mechanical and graft inoculations were used to identify the type of resistance to PVM in potatoes. The parental lines, which resistance to PVM is controlled by the gene Rm or/and Gm, express field resistance even under the high natural infection pressure. Increasing number of resistant to PVM new potato cultivars is expected.