Left – tree showing phylogenetic relationships of the 23 Fusarium species complexes and placement of F. foetens within the F. oxysporum species complex. In the tree, species complex names are abbreviated using specific epithets of the species after which the complexes are named (e.g., the F. sambucinum species complex is abbreviated as sambucinum). Upper right – culture of F. foetens NRRL 38302 growing on potato dextrose agar medium. Lower right – chemical structures of beauvericin and fusaric acid, two mycotoxins produced by F. foetens. Image credit: Robert H. Proctor, Amy McGovern and Crystal Probyn.

Fusarium (family Nectriaceae) is a species-rich fungal genus that poses a dual threat to agriculture because many species cause destructive crop diseases and/or contaminate infected crops with toxic secondary metabolites (mycotoxins) that are health hazards to humans and other animals. Some Fusarium mycotoxins are frequent contaminants of dried distillers’ grains, coproducts of grain-based ethanol production used as a protein-rich livestock feed. In addition, some species of Fusarium are pathogens of energy crops such as corn and sugar cane. Some species can also exist as endophytes in plants, including some bioenergy crops.

DNA-based phylogenetic analyses have resolved Fusarium into 23 multi-species lineages known as species complexes. Fusarium foetens is a member of the Fusarium oxysporum species complex, which includes at least one other species, F. oxysporum. The latter species has an exceptionally broad host range and is one of the most extensively studied Fusarium species. Recent phylogenomic analyses have led to splitting of the species F. oxysporum into multiple species (Achari et al. 2020). Although the degree to which F. oxysporum should be split into multiple species is controversial, the close relationship of F. foetens to, and its phylogenetic distinctiveness from F. oxysporum will aid the understanding of the species diversity within the F. oxysporum species complex. Fusarium foetens can cause a severe wilt disease of some begonia hybrids and is reported to produce beauvericins and fusaric acid, mycotoxins whose effects on the health is poorly understood. Strain NRRL 38302 was isolated from the stem of a Pinus radiata seedling from Valdivia, Chile.

References:
Geiser DM, Al-Hatmi A, Aoki et al. 2021. Phylogenomic analysis of a 55.1 kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani Species Complex. Phytopathology 111: 1064-1079.

Achari SR, Kaur J, Dinh Q, et al. 2020. Phylogenetic relationship between Australian Fusarium oxysporum isolates and resolving the species complex using the multispecies coalescent model. BMC Genomics 21:248.