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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Mycotoxin Prevention and Applied Microbiology Research » Research » Publications at this Location » Publication #320647
Title: Variation in type A trichothecene production and trichothecene biosynthetic genes in Fusarium goolgardi from natural ecosystems of Australia

Author
item ROCHA, L - Royal Botanical Gardens
item LAURENCE, M - Royal Botanical Gardens
item Proctor, Robert
item McCormick, Susan
item SUMMERELL, B - Royal Botanical Gardens
item LIEW, E - Royal Botanical Gardens

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2015
Publication Date: 11/5/2015
Publication URL: http://handle.nal.usda.gov/10113/62297
Citation: Rocha, L.O., Laurence, M.H., Proctor, R.H., McCormick, S.P., Summerell, B.A., Liew, E.C.Y. 2015. Variation in type A trichothecene production and trichothecene biosynthetic genes in Fusarium goolgardi from natural ecosystems of Australia. Toxins. 7(11): 4577-4594.

Interpretive Summary: T-2 toxin is a trichothecene mycotoxin produced by Fusarium species in infected small grains, especially oats and barley. Ingestion of T-2 toxin contaminated grain can result in a variety of symptoms including diarrhea, hemorrhaging and feed refusal. Trichothecenes are also phytotoxic and are important virulence factors in some plant diseases such as wheat head blight. We found that T-2 toxin and related trichothecenes are produced by Fusarium goolgardi, a fungus that grows on Xanthorrhea glauca, a very large plant known as the grass tree in Eastern Australia that can suffer from dieback. We determined the genetic relationship between F. goolgardi and other trichothecene-producing species. The production of T-2 toxin by a fungus isolated from this natural environment suggests that the toxin may contribute to the decline of the grass trees.

Technical Abstract: The fungal species Fusarium goolgardi occurs on the plant Xanthorrhoea glauca in natural ecosystems of Australia and is closely related to fusaria that produce a subgroup (type A) of trichothecene mycotoxins that lack a carbonyl group at carbon atom 8 (C-8). Here, mass spectrometric analysis revealed that F. goolgardi isolates also produce type A trichothecenes, but exhibited one of two production phenotypes (chemotypes). Some isolates produced multiple type A trichothecenes including 4,15-diacetoxyscirpenol (DAS), neosolaniol (NEO), acetyl-neosolaniol (Ac-NEO) and T-2 toxin (DAS-NEO-T2 chemotype), which have an acyl, hydroxyl or no functional group at C-8. Other isolates produced only DAS (DAS chemotype), which has no functional group at C-8. In phylogenies inferred from trichothecene biosynthetic gene (TRI) sequences, F. goolgardi isolates were resolved as a monophyletic clade distinct from other type A trichothecene-producing species. However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus. Phylogenies based on different TRI loci resolved isolates with different chemotypes into distinct clades, even though only the TRI1-TRI16 locus is responsible for structural variation at C-8. Sequence analysis revealed that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but nonfunctional due to point mutation-induced premature stop codons in isolates with the DAS chemotype. These results provide evidence for the genetic basis of trichothecene chemotype variation in F. goolgardi and lead to the question: are the two chemotypes representative of two distinct populations?