Mapping genetic factors controlling potato - cyst nematode interactions

Abstract

The thesis describes strategies for genetic mapping of the genomes of the potato cyst nematode and potato. Mapping in cyst nematodes was achieved by AFLP genotyping of single cysts and subsequent segregation analysis in a family of sibling populations. The genetic map of Globodera rostochiensis comprises nine linkage groups, a number similar to the haploid chromosome number determined. The low kb/cM ratio suggests that map based cloning of (a)virulence genes may be feasible for this organism.For potato, a mapping strategy based on catalogued, chromosome-specific AFLP markers facilitated the mapping of the nematode resistance loci Gpa2 and Grp1 . Gpa2 confers specific resistance to G. pallida and is tightly linked to a virus resistance on potato chromosome 12 . Locus Grp1 is identified by QTL mapping. It confers resistance to G. rostochiensis pathotype Ro 5 , partial resistance to G. pallida and maps on chromosome 5 . The spectra of nematode resistance loci and their positions on the potato genome suggest that these genes are involved in gene-for-gene interactions.</p