'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 SCREENING THE COMMONWEALTH POTATO COLLECTION FOR NOVEL SOURCES OF RESISTANCE TO THE POTATO CYST NEMATODE GLOBODERA PALLIDA L. CASTELLI, G. RAMSAY, S.J. NEILSON, M.S. PHILLIPS SCRI, Invergowrie, Dundee, DD2 5DA, Scotland

Professor Hawkes’ collection of potatoes has been incorporated into the Commonwealth Potato Collection.  The material originates from several expeditions to the Americas and represents a potentially valuable source of resistance to the PCN.  The germplasm screened included taxa mainly from Mexico, Bolivia, Argentina and Peru. Seeds from 197 accessions (66 species) have been screened for resistance to G. pallida and G. rostochiensis.  49.75% had G. pallida resistant clones and 52.11 % had G. rostochiensis resistant clones, from which 17 species are believed to be novel sources of resistance.  The most promising 16 species have been placed into culture for histological tests on the mode of resistance.  Molecular analysis of the resistant species to determine levels of diversity between the species has been done.