|GRAFENHAN, TOM - Canadian Grain Commission|
|JOHNSTON, PETER - Landcare Research|
Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2016
Publication Date: 1/30/2017
Citation: Grafenhan, T., Johnston, P.R., Vaughan, M.M., McCormick, S.P., Proctor, R.H., Busman, M., Ward, T.J., O'Donnell, K. 2017. Fusarium praegraminearum sp. nov. is a novel nivalenol mycotoxin-producing pathogen from New Zealand can induce head blight on wheat. Mycologia. 108(6):1229-1239.
Interpretive Summary: This research was conducted to characterize a novel Fusarium species, which our genetic and genomic data revealed is closely related to the most important head blight pathogens of cereals. Because species within this group are known to contaminate food and feed with toxins, and the whole genome sequence we generated suggested that this species might produce the trichothecene toxin nivalenol, we conducted experiments to assess whether it could produce toxins and induce head blight on wheat. Our experiments revealed that this novel species could produce nivalenol toxin in wheat and in solid and liquid cultures, and induce head blight on wheat. This pathogen was also able to produce zearalenone, which is an estrogenic reproductive toxin. Morphological and molecular genetic data were used to formally describe this novel species as F. praegraminearum, in recognition of its placement as the earliest diverging species lineage within this group of toxigenic plant pathogens. Results of this study should be of interest to mycotoxicologists, fungal biologists, quarantine officials, and plant pathologists who are focused on minimizing the threat that these fungi pose to cereal production worldwide.
Technical Abstract: We report on the molecular and morphological characterization of a novel B-type trichothecene toxin-producing species (i.e., B clade) recovered from litter in a maize field near Wellington, New Zealand, which is described as Fusarium praegraminearum sp. nov. This species was initially identified as F. acuminatum based on select morphological characters; however, it differs from this species in that it produces longer macroconidia in which the apical cell is not as pointed, chlamydospores are not produced, and its colony growth rate on agar is much faster. Molecular phylogenetic analyses of portions of 13 genes resolved F. praegraminearum as the basal most species within the B clade. Mycotoxin analyses demonstrated that it was able to produce 4-acetylnivalenol and 4,15-diacetylnivalenol, the nontrichothecene sesquiterpenes culmorin and hydroxy-culmorins, and the estrogen zearalenone in vitro. Results of a pathogenicity experiment revealed that F. praegraminearum was able to induce moderate head blight on wheat.