Fusarium is a genus that includes the most devastating soil-borne fungal agents. Examples are F. verticillioides (Fv) and F. oxysporum (Fo) that can infect maize and ortive plants, respectively. Fv is the main contaminant of maize seeds stocks and it produce mycotoxins that are highly cancerogenic for animals. The most important Fv mycotoxins are fumonisins due to the high cancerogenic potential. The EU compiled several laws to regulate the concentration of fumonisins in maize seed stocks. The role of mycotoxins is elusive. Our results show that mutants of Fv in the FUM1 gene, the key enzyme in fumonisins production, display no difference in necrosis severity in stalk maize assay. These data suggest that the necrosis is not generated by the effect of the mycotoxins. F. musae (Fm) is a sister species of Fv causing postharvest disease on bananas. Although the two species are genetically similar, they have distinct host ranges with Fm not being able to colonize maize.
Similarly to Fv and Fm, different forma specialis of F. oxysporum have distinct hosts. For example, Fo f.sp. lycopersici (Fol) is able to colonize tomato but not melon while the Fo f.sp. melonis (Fom) infect melon and not tomatoes. As in Fv, the role of mycotoxins in Fo is elusive but there is a lot of information on the role of effectors. The best studied effectors in Fol are the SIX effectors. These effectors are well characterized and play a crucial role in full virulence of Fol in tomato. Some of these effectors are pathogenicity factors. Recently, a single Fom gene was identified to be essential for the host specificity. These results show that a single gene can be responsible for host specificity in Fo species.
The aim of this project is to use comparative genomics to identify specific effectors of Fv essential for the virulence and/or the pathogenicity on maize and to identify the pathogenicity factor that makes Fo f. sp. melongena pathogenic on Solanum melongena when compared to Fol or Fom.
