Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2011
Publication Date: 4/22/2011
Citation: Yli-Mattila, T., Ward, T.J., O Donnell, K., Proctor, R., Burkin, A., Kononenko, G., Gavrilova, O., Aoki, T., McCormick, S.P., Gagkaeva, T. 2011. Fusarium sibiricum sp. nov, a novel type A trichothecene-producing Fusarium from northern Asia closely related to F. sporotrichioides and F. langsethiae. International Journal of Food Microbiology. 147(1):58-68. Interpretive Summary: Mycotoxigenic fungi within the genus Fusarium contaminate grain with trichothecene toxins that pose a significant threat to food safety, animal health, and agricultural production. Despite the economic and public health significance of these fungi, significant gaps exist in our knowledge of Fusarium diversity and toxin production potential. This study was conducted to characterize novel T-2 trichothecene toxin-producing fusarial pathogens isolated from small grain cereals in Asia. The results indicate that these isolates represent a novel species, Fusarium sibiricum, which produces T-2 toxin and other trichothecene toxins. Molecular probes were developed that successfully distinguish F. sibiricum from closely related toxigenic species of Fusarium. These results will improve toxin monitoring and prediction efforts as well as plant disease control programs, and will directly support quarantine officials efforts to prevent the inadvertent introduction of this foreign pathogen into the United States and other non-indigenous areas.
Technical Abstract: Production of type A trichothecenes has been reported in the closely related species Fusarium langsethiae and F. sporotrichioides. Here, we characterized a collection of Fusarium isolates from Siberia and the Russian Far East (hereafter Asian isolates) that produce high levels of the type A trichothecene T-2 toxin and are similar in morphology to the type A trichothecene-producing F. langsethiae, and to F. poae which often produces the type B trichothecene nivalenol. The Asian isolates possess unique macroscopic and microscopic characters and have a unique TG repeat in the nuclear ribosomal intergenic spacer (IGS) region. The TRI1-TRI16 locus in the Asian isolates, which determines type A versus type B trichothecene production in other species, is more similar in organization and sequence to the TRI1-TRI16 locus in F. sporotrichioides and F. langsethiae than to that in F. poae. Phylogenetic analysis of the combined sequences of the TRI1 and TRI16 gene coding regions indicate that the genes in the Asian isolates are more closely related to those of F. sporotrichioides than F. langsethiae. Phylogenetic analysis with combined sequences of the beta-tubulin, translation elongation factor, RNA polymerase II and phosphate permease gene sequences resolved the Asian isolates into a well-supported sister lineage to F. sporotrichioides, with F. langsethiae forming a sister lineage to F. sporotrichioides and the Asian isolates. The Asian isolates are conspecific with Norwegian isolate IBT 9959 based on morphological and molecular characters. In addition, the European F. langsethiae isolates from Finland and Russia were resolved into two distinct subgroups based on translation elongation factor and IGS sequences. Nucleotide polymorphisms within the IGS rDNA were used to design PCR primers that successfully differentiated the Asian isolates from F. sporotrichioides and F. langsethiae. Based on these data, we formally propose that the Asian isolates together with Norwegian isolate IBT 9959 comprise a novel phylogenetic species, F. sibiricum, while the two subgroups of F. langsethiae only represent intraspecific groups.