Wild potato species of the series Pinnatisecta - progress in their utilisation in potato breeding

Somatic hybrids between genebank accessions of three species of the series Pinnatisecta: Solanum cardiophyllum, S. pinnatisectum and S. tarnii, and commercial cultivars were produced and characterised for resistance to potato virus Y (PVY), foliage blight (Phytophthora infestans) and agronomic traits. The somatic hybrids were backcrossed with cultivated potato to produce BC progenies. Resistance to PVY was assessed by mechanical inoculation of green-house grown plants using isolates of five virus strains (N, O, NTN, NW, C) and by exposure to viruliferous aphid vectors in the field. The tuber quality and tuber yield of selected hybrids and BC clones were evaluated in the field. Parental clones, somatic hybrids and BC progenies were assessed for resistance to foliage blight by the detached-leaflet assay and artificial inoculation in the field with zoospores of P. infestans. Results suggest that both resistance traits were transferred to somatic hybrids by protoplast fusion and that they persist in BC clones with some segregation for resistance to foliage blight and PVY occurring in the BC1 and BC2 population.