Phenotypic and molecular characterization of potato germplasm for potato cyst nematode resistance

Potato cyst nematode (PCN) is considered to be the most devastating pest causing major yield losses in potato worldwide. Resistant potato cultivars would be the most effective strategy to control PCN however, they may not posses enough resistance to all pathotypes of PCN. Therefore breeding programme should focus on developing varieties with horizontal resistance which can be achieved by using parental lines with multiple resistant genes. Hence, the present study was conducted to characterize the phenotypic and genotypic resistance of parental lines against PCN and also an attempt was made to find out the pollen viability of the parental lines to improve the breeding efficiency. Sixty six genotypes were screened phenotypically as well as genotypically against PCN. Out of which, 54 lines were found phenotypically resistant to G. rostochiensis, 48 to G. pallida and 44 to both the species of PCN. The same set of parental lines was also validated using linked molecular markers. In molecular characterization, the markers linked with H1 gene (TG689 and 57R) were found in majority of the parental lines screened. Marker SPUD 1636 linked to GPa5 QTL was positive for three genotypes whereas HC marker (GPaV(vm) QTL) was positive for 30 parental lines. TG432 linked to Grpl gene is positive for 27 parental lines whereas the marker Gro 1-4-1 is not amplified in any of the screened parental lines. Pollen viability of parental lines varied from 15.8 to 93.6%. The results of the study will facilitate breeding of novel resistant varieties by efficient selection of ideal male parent with good pollen potential and multiple resistance to several PCN pathotypes.