Identification of RAPD markers linked to fusarium crown and root rot resistance (Frl) in tomato

In tomato (Lycopersicon esculentum Mill.) a single dominant gene (Frl) on c hromosome 9 confers resistance to fusarium crown and root rot (crown rot) i ncited by Fusarium oxysporum f. sp. radicis-lycopersici. To identify random ly amplified polymorphic DNA (RAPD) markers linked to Frl, crown rot suscep tible and resistant tomato lines were screened for polymorphisms using 1000 random 10-mer primers and three reliable RAPD markers were found linked to Frl (UBC #'s 116, 194, and 655). A codominant polymorphic PCR marker of TG 101, a restriction fragment length polymorphic (RFLP) marker linked to Frl, was developed to facilitate the linkage studies. Using TG101 and the four RAPD markers, on a Fi-l segregating backcross population of 950 plants indi cated that all belong to the same linkage group. The polymorphic allele ord er was found to be TG101 - 655 - 116 - 194 - Frl. UBC 194 was found to be 5 .1 cM from Frl in this population. Furthermore, it was the only marker foun d in the resistant genotypes 'Mocis' and Fla 7226, whereas resistant genoty pes 'Momor', Ohio 89-1, and Fla 7464 all had UBC 194 and UBC #'s 116, 194, and 655.