Abstract

The Fusarium wilt caused by Fusarium oxyspoum f. sp. lycopersici (FOL) is a major biotic constraint for tomato production. The pathogenicity of this fungus is variable and it has not been well characterized in tomato. 30 FOL isolates representative of the three races were analyzed by random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and restriction fragment length polymorphism of intergenic spacer (RFLP-IGS) using DNA bulks for each race. Ten RAPD primers and 20 ISSR primers were selected, generating a large number of polymorphic bands. Among the tested primers, four ISSR (UBC 810, UBC 812, UBC 817, UBC 820) and four RAPD primers (OPB07, OPA08, OPA 18, OPA 20) revealed a specific fragment to races 1 and 3. Using the marker IGS, cutting with the enzymes HinfI, RsaI, AluI and HaeIII produced polymorphism information enabling the identification and genetic characterization among isolates of three races of this pathogen. Cluster analysis with UPGMA using genetic distance showed that the isolates of the three races belonged to two groups. Group 1 contained isolates of the races 1 and 2 and isolates of race 3 were placed in group 2. The results demonstrate the importance of molecular marker utilization in genetic characterization with the aim of rapid and accurate identification of these pathogens in tomato cropping systems in Brazil.

Key words: Fusarium wilt, tomato disease, molecular analysis, Solanum lycopersicum.