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Title: A polyphasic approach for characterization of a collection of cereal isolates of the Fusarium incarnatum-equiseti species complex

item VILLANI, ALESSANDRA - National Research Council - Italy
item MORETTI, ANTONIO - National Research Council - Italy
item DE SAEGER, SARAH - Ghent University
item HAN, ZHENG - Ghent University
item DI MAVUNGU, JOSE - Ghent University
item SOARES, CELIA - University Of Minho
item Proctor, Robert
item VENANCIO, ARMANDO - University Of Minho
item LIMA, NELSON - University Of Minho
item LOGRIECO, ANTONIO - National Research Council - Italy
item SUSCA, ANTONIA - National Research Council - Italy

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2016
Publication Date: 6/22/2016
Publication URL:
Citation: Villani, A., Moretti, A., De Saeger, S., Han, Z., Di Mavungu, J.D., Soares, C.M., Proctor, R.H., Venancio, A., Lima, N., Stea, G., Paciolla, C., Logrieco, A.F., Susca, A. 2016. A polyphasic approach for characterization of a collection of cereal isolates of the Fusarium incarnatum-equiseti species complex. International Journal of Food Microbiology. 234:24-35.

Interpretive Summary: Collectively, species of the fungus Fusarium can cause diseases on almost all crops and can produce toxins that pose a risk to the health of humans and livestock animals. Analysis of DNA sequence variation has been used to divide Fusarium into groups of closely related species, or species complexes. The Fusarium incarnatum-equiseti species complex (FIESC) consists of at least 30 species, designated FIESC 1 – FIESC 30. These fungi occur in various habits, including on plants and animals. However, it is not clear whether any the species predominate on a particular host or group of hosts. To assess what FIESC species can occur on cereal crops, we characterized a collection of 69 Fusarium strains with FIESC-like morphology that were obtained from barley, corn, oats, rice or wheat from Europe or North America. Analysis of DNA sequence variation indicate that the strains are members of four previously described and one novel FIESC species. However, 55% of the isolates were members of the same species, FIESC 5. These data suggest that relatively few FIESC species predominate on cereals in Europe and North America. Analysis of a subset of the isolates for toxin production revealed that all isolates produced a group of toxins known as trichothecenes but differed in the kinds of trichothecenes produced. Thus, members of FIESC that occur on cereals have the potential to contaminate grain with trichothecene toxins. This research will be of use to academic, government and industrial scientists who assess health risks posed by fungi and develop strategies to reduce toxin contamination in crops.

Technical Abstract: DNA-based phylogenetic analyses have resolved the fungal genus Fusarium into multiple species complexes. The F. incarnatum-equiseti species complex (FIESC) includes fusaria associated with several diseases of agriculturally important crops, including cereals. Although members of FIESC are considered to be moderately aggressive, they are able to produce a diversity of mycotoxins, including trichothecenes, that can accumulate to harmful levels in cereals. FIESC exhibits high levels of cryptic speciation, and as a result it is often necessary to use approaches other than morphological characterization to distinguish between species. In the current study, we used a polyphasic approach to characterize a collection of 69 FIESC isolates recovered from cereals in Europe and North America. In a species phylogeny inferred from nucleotide sequences of the four housekeeping genes, 65 of the isolates were resolved within the Equiseti clade of FIESC, and four isolates were resolved within the Incarnatum clade. Seven isolates were not resolved within the previously described phylogenetic species, suggesting that they are a novel species, designated here as FIESC 31. Phylogenies based on nucleotide sequences of trichothecene biosynthetic genes and MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry) data were largely concordant with the housekeeping gene-based species phylogeny. Finally, Liquid Chromatography (Time-Of-Flight) Mass Spectrometry [LC-(TOF-)MS(/MS)] revealed variability in mycotoxin production profiles among the different phylogenetic species and haplotypes investigated in this study.