NX-Toxins from Fusarium graminearum isolates in western Canada

Fusarium graminearum is considered an important plant pathogen, especially on the cereal crops, given the significance of the fusarium head blight it causes, severity, and accompanied economic losses. Every year significant quantities of grain becomes unfit for human and animal consumption due to mycotoxin contamination leading to huge economic losses world-wide. Over the past decade, newer mycotoxins known as NX toxins, were observed, produced by Fusarium species. Under the changing climate, where increased precipitation, moisture, temperature are a common occurrence, there is an increased risk of incidence of fungal diseases and subsequent accumulation of new and modified mycotoxins. Recently, a small percentage of Fusarium graminearum strains from Canada and U.S. were found to produce a novel NX-2 toxin in cereal crops. These new F. graminearum strains could pose a new threat to food safety in Canada and world-wide. However, the lack of reliable molecular and analytical methods to detect NX-2 isolates have limited the early detection and study of the novel NX-producing isolates in Canada. In the current study, Fusarium graminearum isolates and analytical methods targeting NX toxins were investigated. These methods will help in monitoring NX-producing isolates world-wide, characterizing their trends in the spatial and temporal dynamics, as well as promote early detection of emerging threats to plant, human, and animal health.
Seven days old Fusarium graminearum isolates were sub-cultured in sterile rice for 10 days. Ground rice samples were extracted for mycotoxins (NX-2, NX-3, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and nivalenol) with a solvent mixture containing acetonitrile, methanol, and water followed by sonication and centrifugation. The separated supernatant was filtered and an aliquot was evaporated to dryness under vacuum. Dried extracts were re-suspended in solvent matching the mobile phases used for separation of analytes on liquid chromatography column. A labelled internal standard was added followed by analysis using an ultra-high performance liquid chromatograph coupled with an orbitrap tribrid mass spectrometer.
Preliminary results indicate a strong correlation between NX-2 toxins and other trichothecene mycotoxins. The details of this correlations and significance of these finding will be presented. These findings will help develop proactive mitigation strategies to increase resiliency in agriculture and achieve food security.