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Ontario Grain Farmer Magazine

Understanding the fitness of Fusarium graminearum isolates after inoculation and the impact of environment towards the identification of commercial winter wheat varieties with consistently low DON levels

Principal Investigator: Helen Booker

Research Institution: University of Guelph

Timeline: April 2024 – March 2025   

Objectives:

  • Prepare inoculum and screen Fusarium graminearum (Fg) (chemotypes 3ADON, 15ADON, and their mixtures) used in Ontario inoculated Fusarium nurseries, and new 15ADON/3ANX-producing Fg isolates from commercial fields in Ontario, to screen moderately resistant (MR), moderately susceptible (MS), and susceptible/highly susceptible (S/HS) checks in Orthogonal variety trials.
  • Determine wheat genotype Type II resistance x Fg isolate interactions using point inoculation under controlled environment conditions.
  • Determine Fg isolate fitness, Fusarium head blight (FHB) symptom development, deoxynivalenol (DON) production potential, Fusarium damage kernels (FDK) level, and genotype x Fg isolate interaction (Type 1 resistance as the incidence rating and Type II resistance as the severity rating) using spray inoculation at the Ridgetown Fusarium nursery.
  • Use a biplot analysis to identify weather variables associated with FHB visual symptoms and DON in grain of commercial winter wheat varieties evaluated at inoculated Fusarium nurseries in Ontario. Determine the correlation between FHB visual symptoms and DON value in grain for commercial wheat varieties evaluated at inoculated Fusarium nurseries in Ontario.
  • Develop ‘best’ sampling protocols (e.g., replications, sample size) when using enzyme linked immune assay (ELISA) for DON evaluation of commercial wheat varieties evaluated at inoculated Fusarium nurseries in Ontario.
  • Understand the role of natural infection and/or prevalence of specific Fg isolates impacting infection in inoculated Fusarium nurseries in Ontario.

Impacts:

  • The most significant impact of FHB is the loss of grade (and subsequent price discount) of harvested grain and food safety concerns due to DON. The results of this research will help ensure the ranking of winter wheat entries in Ontario Registration and Performance trials are valid, and will help mitigate this serious issue in future winter wheat cultivars developed for production in Ontario.

Scientific Summary:

Cereal production in Ontario suffers from Fusarium graminearum infections (Fg; the causal agent of Fusarium blight (FHB) in wheat), which decrease crop yield and result in trichothecene mycotoxin accumulation, including deoxynivalenol (DON) in harvested grain. A critical negative impact of FHB is reduced harvested grain quality. When the grade drops from #1 to #2, the cost is ~$12/acre for farmers; a drop to #3 costs the farmer $35-$101/acre. Long-term rotation studies demonstrate wheat in Ontario rotations increases row crop yields and profits. Rotation sites at Elora and Ridgetown that included small grains had superior soil structure, organic matter, and soil health scores. Global climate change may affect water availability, further limiting crop yields. Improving soil structure by including winter wheat in crop rotations could address both issues. However, FHB susceptibility must be addressed to support efforts to promote winter wheat in crop rotations in Ontario.

During the 1990s, Canadian crops lost approximately $520M due to FHB. Breeding for genetic resistance is an effective and environmentally friendly FHB management strategy, but it can be difficult. Moderately resistant varieties (e.g., Marker) are showing susceptibility to a mixture of 3ADON and 15ADON Fg chemotypes under inoculated field conditions. The inoculated Fusarium nurseries at Ridgetown, Elora and Ottawa are important for screening new/existing wheat varieties against FHB. Screening results are heavily impacted by the environment; daily temperatures now fluctuate between 10 and 20 degrees Celsius during the growing season due to climate change. This study will evaluate several components of protocols currently used to screen wheat lines in inoculated FHB nurseries and will provide the best methodology to determine resistance/tolerance to DON in winter wheat. The results may change the evaluation protocols and will identify the effect of Fg chemotypes and the interaction between Fg chemotypes and wheat varieties, allowing better identification of winter wheat varieties with resistance to DON accumulation for commercial production in Ontario.

External Funding Partners:

None.