Identification of amplified restriction fragment polymorphism (AFLP) markers tightly linked to the tomato Cf-9 gene for resistance to Cladosporium fulvum.

Using the technique of amplified restriction fragment polymorphism (AFLP) analysis, and bulked segregant pools from F2 progeny of the cross Lycopersicon esculentum (Cf9) x L. pennellii, approximately 42,000 AFLP loci for tight linkage to the tomato Cf-9 gene for resistance to Cladosporium fulvum have been screened. Analysis of F2 recombinants identified three markers which co-segregated with Cf-9. The Cf-9 gene has recently been isolated by transposon tagging using the maize transposon Dissociation (Ds). Analysis of plasmid clones containing Cf-9 shows that two of these markers are located on opposite sides of the gene separated by 15.5 kbp of intervening DNA. AFLP analysis provides a rapid and efficient technique for detecting large numbers of DNA markers and should expedite plant gene isolation by positional cloning and the construction of high-density molecular linkage maps of plant genomes.