Identification of elite potato genotypes possessing multiple disease resistance genes through molecular approaches

• Resistant genes to the most important pathogens affecting potato yields viz., Phytopthora infestans, PVY and PCN were studied.
• Exotic and indigenous potato accessions (126) were phenotypically and genotypically characterized.
• This study validates the association of phenotypic resistance with the presence/absence of diagnostic marker linked with the gene of interest.
• Fourteen elite potato genotypes possessing multiple resistance genes are proposed which can be used as parents in various resistance breeding programmes through marker assisted selection (MAS).

World potato productivity including India was almost stagnant during the last two decades largely due to yield losses by biotic and abiotic stresses. Among biotic stresses, late blight, viruses and nematodes are the most devastating. Varieties resistant to individual stress have been deployed but the production remained limited because of other biotic stresses affecting the crop. Potato cultivars having multiple disease resistance are urgently required to boost production. Resistance to late blight is both qualitative and quantitative while extreme resistance to PVY can be imparted by the single dominant genes Ryadg and Rysto. Likewise resistance to potato cyst nematode is mainly imparted by the single dominant H1 and Gro1-4 genes. All these genes have been mapped and tightly linked molecular markers are available to perform marker-assisted selection (MAS). In the present study 126 parental clones were characterized for the presence of genes for resistance to late blight (R1, R2, R3a), PVY (Ryadg, Rysto) and potato cyst nematodes (H1, HC_QRL and Gro1-4) using molecular markers. The same clones were evaluated for disease resistance with standard phenotypic assays. Fourteen elite potato genotypes possessing multiple disease resistance genes were identified by means of linked molecular markers and their resistances were confirmed through phenotypic screening methods. These genotypes can be exploited as parents for hybridization to expedite the potato resistance breeding programmes.