The Cf-ECP2 gene is linked to, but not part of, the Cf-4/Cf-9 cluster on the short arm of chromosome 1 in tomato

A gene has been identified in tomato, which confers resistance to Cladospor ium fulvum through recognition of the pathogenicity factor ECP2. Segregatio n analysis of F-2 and F-3 populations showed monogenic dominant inheritance , as for previously reported Cf resistances. The gene has been designated C f-ECP2. Using several mapping populations, Cf-ECP2 was accurately mapped on chromosome 1, 7.7 cM proximal to TG236 and 6.0 cM distal to TG184. Althoug h Cf-ECP2 is linked to Cf-4, it is not located in the Hcr9 cluster "Milky W ay". Therefore, Cf-ECP2 is the first functional Cf homologue on chromosome 1 that does not belong to this Hcr9 cluster. No recombination events betwee n Cf-ECP2 and CT116 have been observed in three populations tested, represe nting 282 individuals. The low value for the physical distance per cM aroun d CT116 reported previously and the high probability that Cf-ECP2 is also a member of a Hcr9 cluster will facilitate cloning of the locus.