Toxin Profile, Fertility and AFLP Analysis of Fusarium verticillioides from Banana Fruits

Gibberella fujikuroi is composed of at least nine mating populations (MPs), corresponding to biological species and assigned letters (from A to I). Each MP possesses a specific toxicological profile and a preferential host. Members of Fusarium verticillioides and F. thapsinum, anamorphs respectively of MPs A (G. moniliformis) and F (G. thapsina), share identical morphological traits, but they have a different preferential hosts (maize and sorghum, respectively) and toxin profiles, beingable the only member of MP A to produce fumonisins and the only member of MP F to produce moniliformin. Isolates from banana fruits were identified morphologically as F. verticillioides. The isolates were analyzed for fumonisin and moniliformin production. While none of the isolates produced fumonisin, all the isolates produced moniliformin. The isolates were crossed with tester strains of MPs A and F, showing ability to produce fertile perithecia only when crossed by MP A tester strains isolated from maize. However, the time required for the formation of fertile perithecia and their size differed significantly from the usual fertile crosses of strains belonging to MP A. Pathogenicity tests using such isolates of F. verticillioides isolated from banana and a set of F. verticillioides isolates isolated from maize were also performed on banana fruits. The data showed that the isolates from banana were more pathogenic. Finally, isolates from banana and maize were compared using AFLP. The results revealed that isolates from banana and maize produced two distinctly different clusters. In conclusion, isolates of F. verticillioides from banana showed specific traits (toxin production, in vitro fertility, pathogenicity and molecular profiles), that were different to those of the same species from maize. This could reflect important differences in the ecology and natural history of the population from banana and should encourage further investigations into the mechanisms of toxin production and pathogenicity within the same MP.