Identification and Characterization of Spontaneous Auxotrophic Mutants in Fusarium langsethiae

Different diagnostic approaches for the characterization of the fungal community and Fusarium species complex composition of Italian durum wheat grain and correlation with secondary metabolite accumulation

BACKGROUND

The evolution of the fungal communities associated with durum wheat was assessed using different diagnostic approaches. Durum wheat grain samples were collected in three different Italian cultivation macro-areas (north, center and south). Fungal isolation was realized by potato dextrose agar (PDA) and by deep-freezing blotter (DFB). Identification of Fusarium isolates obtained from PDA was achieved by partial tef1α sequencing (PDA + tef1α), while those obtained from DFB were identified from their morphological characteristics (DFB + mc). The fungal biomass of eight Fusarium species was quantified in grains by quantitative polymerase chain reaction (qPCR). Fungal secondary metabolites were analyzed in grains by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Correlations between Fusarium detection techniques (PDA + tef1α; DFB + mc and qPCR) and mycotoxins in grains were assessed.

RESULTS

Alternaria and Fusarium showed the highest incidence among the fungal genera developed from grains. Within the Fusarium community, PDA + tef1α highlighted that F. avenaceum and F. graminearum were the most represented members, while, DFB + mc detected a high presence of F. proliferatum. Alternaria and Fusarium mycotoxins, principally enniatins, were particularly present in the grain harvested in central Italy. Deoxynivalenol was mainly detected in northern-central Italy.

CONCLUSIONS

The adoption of the different diagnostic techniques of Fusarium detection highlighted that, for some species, qPCR was the best method of predicting their mycotoxin contamination in grains. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Draft Genome Sequences of Prototrophic and Biotin-Auxotrophic Fusarium langsethiae Strains Isolated from an Oat Grain in the Northern Region of Russia

Fusarium langsethiae is a suspected plant-pathogenic fungus causing cereal contamination with trichothecene mycotoxins. Here, we report the genome sequences of two F. langsethiae strains, MFG217701 (a prototroph) and MFG217702 (a biotin auxotroph), isolated from a grain of oat harvested in Russia.

Levels of T-2 toxin and its metabolites, and the occurrence of Fusarium fungi in spring barley in the Czech Republic

Mycotoxins have been widely studied by many research groups but further multidisciplinary research is needed to better understand and clarify many issues. This study describes the use of high-performance liquid chromatography coupled with ion trap mass spectrometry (HPLC-MS) to measure T-2 toxin and its metabolites, such as HT-2 toxin, neosolaniol (NEO) and diacetoxyscirpenol (DAS), as well as masked glucosylated mycotoxins in Fusarium-infected Czech spring barley. In total, 152 spring barley samples from the 2018 harvest were analyzed by the ELISA screening method for the presence of T-2 toxin. The most contaminated samples (15), which exceeded the recommended maximum level set by the EU for the sum of T-2 and HT-2 toxin in unprocessed cereals (200 μg/kg), were analyzed by HPLC-MS/MS and microbiological testing. Isolated fungi were evaluated microscopically and identified by polymerase chain reaction (PCR) assays. The prevalence of Fusarium species in spring barley across the Czech Republic in 2018 showed a predominance of F. poae (12 barley samples) and F. tricinctum (9 barley samples). Other strains (F. sporotrichioides and F. langsethiae) were present at a lower frequency, in 1 and 2 samples, respectively. The average concentration of T-2 plus HT-2 toxin was 107.7 μg/kg, while NEO and DAS were found in a few samples at values close to their limit of quantification. HT-2 glucoside was identified in all samples.

Cultivation Area Affects the Presence of Fungal Communities and Secondary Metabolites in Italian Durum Wheat Grains

In this study, durum wheat kernels harvested in three climatically different Italian cultivation areas (Emilia Romagna, Umbria and Sardinia) in 2015, were analyzed with a combination of different isolation methods to determine their fungal communities, with a focus on Fusarium head blight (FHB) complex composition, and to detect fungal secondary metabolites in the grains. The genus Alternaria was the main component of durum wheat mycobiota in all investigated regions, with the Central Italian cultivation area showing the highest incidence of this fungal genus and of its secondary metabolites. Fusarium was the second most prevalent genus of the fungal community in all cultivation environments, even if regional differences in species composition were detected. In particular, Northern areas showed the highest Fusarium incidence, followed by Central and then Southern cultivation areas. Focusing on the FHB complex, a predominance of Fusariumpoae, in particular in Northern and Central cultivation areas, was found. Fusariumgraminearum, in the analyzed year, was mainly detected in Emilia Romagna. Because of the highest Fusarium incidence, durum wheat harvested in the Northern cultivation area showed the highest presence of Fusarium secondary metabolites. These results show that durum wheat cultivated in Northern Italy may be subject to a higher FHB infection risk and to Fusarium mycotoxins accumulation.

Analysis of Toxigenic Fusarium Species Associated with Wheat Grain from Three Regions of Russia: Volga, Ural, and West Siberia

Wheat grains collected in three regions of Russia—Volga, Ural, and West Siberia—were analyzed for triangulation of methods in analysis of toxigenic Fusarium species. The presence of fungi and quantitative content of their biomass were detected by using various analytical methods, including a mycological and immunochemical methods, and quantitative PCR. Additionally, an enzyme-linked immunosorbent assay and high-performance liquid chromatography with tandem mass spectrometry were applied for determination of mycotoxins. Regional differences were found regarding the contamination of wheat grain by Fusarium fungi and their toxins. The most important observation was the detection of F. graminearum in the Ural and West Siberian regions, where this pathogen had not been found previously. A maximum damaged grains by F. graminearum and F. sporotrichioides was found in the grain samples from West Siberia. The DNA of F. graminearum was detected in 19.2% and DNA of F. sporotrichioides was found in 84.1% of the analyzed grain samples. The amount of Fusarium antigens in the grain samples from the West Siberian region was 7–8 times higher than in the grain samples from the other two regions. Significant contamination of the grain with deoxynivalenol and T-2/HT-2 toxins (maximum contents were 2239 ppb and 199 ppb, respectively) was detected in the West Siberian region.