Pathogenicity And Toxicity Offusarium Tucumaniaeandfusarium Crassistipitatumto Soybean Andarabidopsis Thaliana

Sudden death syndrome (SDS) of soybean is a fungal disease caused by at least four distinctFusariumspecies:F.tucumaniae,F.virguliforme,F.brasiliense, andF.crassistipitatum. All four species are present in Argentina. These fungi are soilborne pathogens that only colonize roots and cause root necrosis. However, damage also reaches the aboveground part of the plant, and foliar chlorosis and necrosis, followed by premature defoliation, can be observed. Although the pathogenicity and phytotoxicity ofF.virguliformehas been well characterized, knowledge regarding disease development by other fungal species is scarce. In this study, two plant species, soybean (Glycine max) andArabidopsis thaliana, and isolates from two fungal species,F.tucumaniaeandF.crassistipitatum, were used to comparatively analyse the fungal pathogenicity and the phytotoxicity of volatile organic compounds (VOCs) and cell-free culture filtrates. Fungal inoculation had a significant effect on plant growth, regardless of the plant species. In addition, infected soybean plants showed disease incidence and foliar and root symptoms. Inhibition ofA.thalianagrowth was not due to VOCs emitted by fungi. Instead, both pathogens were shown to produce toxins that caused typical SDS foliar symptoms in soybean and root length reduction inA.thaliana. As far as we know, this is the first report that demonstrates thatF.tucumaniaeandF.crassistipitatumaffectA.thalianagrowth and emit VOCs, and thatF.crassistipitatumproduces toxins.