2 COMPLEX RESISTANCE LOCI REVEALED IN TOMATO BY CLASSICAL AND RFLP MAPPING OF THE CF-2, CF-4, CF-5, AND CF-9 GENES FOR RESISTANCE TO CLADOSPORIUM-FULVUM

To develop effective strategies for cloning tomato genes for resistance to Cladosporium fulvum, we have tested the reported genetic locations of four such Cf genes. Cf-2 has been reported to be on chromosome 6, Cf-4 on chromosome 1, Cf-5 on chromosome 4, and Cf-9 on chromosome 10. Our mapping studies confirm that Cf-2 is on chromosome 6. Cf-5 is not on chromosome 4, but on chromosome 6 at the same location as Cf-2. Classical mapping places both Cf-2 and Cf-5 approximately 2 centiMorgans (cM) proximal to yv on the long arm of chromosome 6, and less than 1 cM from tl on the short arm. Restriction fragment length polymorphism (RFLP) mapping places Cf-2 close to the chromosome 6 marker TG232. Cf-4 is on the short arm of chromosome 1, loosely linked and distal to the visible marker au. Cf-9 is not on chromosome 10, but on chromosome 1 at the same location as Cf-1. Classical mapping places Cf-9 approximately 14 cM distal to au and approximately 19 cM from ses, loosely linked to the chromosome 1 markers irr, Lpg, and com, but unlinked to ms-32, imb, and br. RFLP mapping places Cf-9 between the chromosome 1 markers TG236 and TG301. Tests for allelism show that Cf-2 is allelic or very closely linked to Cf-5 and that Cf-4 is allelic or very closely linked to Cf-9.