'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 ISOLATION AND CHARACTERISATION OF A WIDE-SPECTRUM NEMATODE RESISTANCE GENE (HERO) OF TOMATO A. KUMAR, K. ERNST, A. HOLT, M. SOBCZAK, M. PHILLIPS, M. GANAL Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA Scotland

Potato cyst nematodes (PCN; Globodera rostochiensis and G. Pallida) are major pests worldwide.  Major resistance genes to both species are lacking in potato cultivars and their related wild Solanum species, which is hindering the potato-breeding programme.  We have shown that the major nematode resistance gene (Hero) from tomato confers resistance (<80%) to both species of PCN G. Rostochiensis and G. pallida.  This, the Hero gene could be very valuable for incorporating PCN resistance in potato cultivars.  Comparative microscopical studies of the infected in vitro roots of susceptible tomato cultivar Money maker (MM) and Hero containing tomato lines with Ro1 have revealed that the resistant response conferred by the Hero gene is activated after establishment of a functional syncytium.  Moreover, a series of changes occurs in resistant plants leading to formation of a layer of necrotic cells separating the syncytium from stellar conductive tissues and this is followed by degradation of the syncytium.  A number of cosmid clones ranging from 10-20 Kb spanning the Hero locus have been identified and cosmid-based transformation constructs in Agrobacterium have been used to introduce into the PCN susceptible tomato line Money Maker.  PCN test on these transgenic plants has revealed that one of the cosmid clones contains the functional copy of the Hero gene.  Furthermore, sequencing analysis has revealed that the Hero gene belongs to a multigene family, which comprises 14 copies (6 of them are truncated), of the Hero gene homologue.  Presently, we are testing the ability of the tomato Hero gene to confer resistance against species in potatoes.