Mapping of Ve in tomato: a gene conferring resistance to the broad-spectrum pathogen, Verticillium dahliae race 1

The soil-borne fungi Verticillium spp. cause vascular wilt disease in a wid e range of crop plants. In tomato, resistance to Verticillium dahliae race 1 is conferred by a single dominant gene, Ve. Previous efforts to map Ve in tomato have yielded confusing results, locating it on different chromosome s, which subsequently raised the possibility that Verticillium resistance m ay be controlled by a number of loci. We used three different mapping popul ations to obtain an unambiguous map location of Ve: a recombinant inbred (R I) line population; an F-2 population segregating for Verticillium resistan ce; and a population of 50 introgression lines (IL). In all of the mapping populations Ve was positioned on the short arm of chromosome 9 tightly link ed to the RFLP marker GP39. This linkage was confirmed by screening for GP3 9 in different breeding lines with known resistance or susceptibility to Ve rticillium. A perfect match was found between GP39 and the Verticillium res ponse of the lines, indicating the potential of GP39 in the rapid detection of Verticillium resistance and as a starting point for map-based cloning o f Ve. This approach is particularly relevant for Verticillium dahliae race 1, since in the present work we also show that the isolate that infects tom ato is responsible for wilt disease in other important crop plants.