Identification of potato hybrids resistant to late blight using R-gene markers and artificial infection

Relevance. Late blight is a disease associated with significant economic losses in potatoes. Losses from this disease in Russia average over 4 million tons annually. The optimal strategy for containing and combating the spread of the pathogen is the development of resistant potato varieties carrying one or more Rpi genes combined with a high level of horizontal resistance. The aim of research. To identify late blight-resistant genotypes among hybrids of different genetic origins and correlate their resistance level with the presence of Rpi genes. Materials and methods. The study involved potato hybrids of different genetic origins, selected for their agronomic and biological traits from 45 crosses. Resistance to late blight was assessed using a laboratory method, artificially infecting leaves and tubers. The presence of molecular markers was assessed using PCR methods using previously published SCAR markers for five Rpi genes (R1, R2, R3a, R3b, and Rpi-blb1 = Rpi-sto1). Results. The screening identified 24 hybrids with high and very high foliar resistance, most of which carried at least one Rpi gene. The R2 gene was predominant among the very highly resistant and resistant samples. The R1 gene was more common in the group of hybrids with moderate resistance and without leaf resistance. Tuber resistance level does not depend on the number and combination of Rpi genes and is likely controlled by a different set of genes. These results reflect the complexity of genotype-phenotype interactions in the potato plant-Phytophthora infestans system. To increase the efficiency of using molecular markers in breeding for the production and selection of late blight-resistant potato genotypes, it is necessary to expand the range of tested markers of known R-genes and conduct an analysis of the original parental forms, on the basis of which to evaluate the hybrid offspring.