Assessment of Genes R1 and R3 Conferring Resistance to Late Blight and of Gene R Ysto Conferring Resistance to Potato Virus Y in Two Wild Species Accessions and their Hybrid Progenies/ Izturîbas Pret Lakstu Puvi Gçnu R1 Un R3 Un Izturîbas Pret Kartupeïu Vîrusu Y Gçna Rysto Novçrtçjums Divu Savvaïas Sugu Lînijâs Un To Hibrîdos

The oomycete Phytophthora infestans Mont. (de Bary), which causes potato late blight, and Potato Virus Y (PVY) are economically important potato pathogens. More virulent P. infestans strains have evolved and are able to overcome resistance genes introgressed earlier to cultivated potato from wild Solanum species, especially from S. demissim Lindl. Potato cultivars resistant to the previously common type of PVY^N may be susceptible to the more virulent isolates of PVY. In previous research, S. guerreroense Corr. (grr) and S. neoantipoviczii Buk. (nan) accessions were rated as resistant to P. infestans and to two (grr) and three (nan) strains of PVY. These parental accessions and their respective hybrid offspring were screened using polymerase chain reaction (PCR) tests to detect alleles conferring resistance to P. infestans (R1 and R3) and to PVY (Ry_sto). Screenings were made in detached leaflet tests (P. infestans), and with the aid of ELISA tests (PVY). The resistance of two hybrids derived from grr was rated as high, mostly due to a hypersensitivity reaction. The allele R3 was detected in only one grr plant among 20 plant populations for each grr and nan accession. R1 and R3 alleles were more frequently detected in one hybrid of grr (grr × B.d.R5.). The resistance allele Ry_sto was found in nan and provided host plant resistance to three strains of PVY, including PVY^NTN. Hybrids derived from this accession were characterised by a high frequency of plants bearing the resistant allele Ry_sto. In the parental clone tbr × phu, as well as in grr and its hybrids, only the susceptible allele at Ry_sto locus was detected.