- Agronomic: corn
- Pest Management: genetic resistance, prevention
Fusarium graminearum is the primary causal fungal pathogen of Fusarium root rot, Giberella stalk rot, and Fusarium ear rot in grain corn production in New York State. Besides causing direct yield losses, F. graminearum presents a severe risk to public health by producing mycotoxins, and a perennial agricultural concern by persisting in arable fields. Despite these detrimental effects, F. graminearum resistance among grain corn hybrids has not been evaluated, exposing growers to yield losses, and exacerbating endemic crop diseases associated with this destructive fungal pathogen. In the present proposal, an accurate evaluation system of F. graminearum resistance will be developed by quantifying morphological features, mycotoxin and plant defense compound accumulation, as well as expression of mycotoxigenic and plant defense marker genes during F. graminearum infection of maize seedlings. These characteristics will be measured in 14 long-season grain corn hybrids grown under controlled laboratory conditions and inoculated with 13 F. graminearum isolates collected in New York State. Characteristics significantly correlated with disease severity, mycotoxin production, and the rate of infection spread across tested plant and fungal genotypes will constitute a disease severity prediction system. Finally, the accuracy of this prediction system will be verified with field-collected corn seedlings naturally infected by F. graminearum. Establishment of this predictive evaluation system will help farmers to choose the most resistant grain corn hybrid for the particular F. graminearum genotypes that are present in their soil. Thereby, farmers will increase productivity, reduce disease management costs, and avoid subsequent mycotoxin contamination of their grain.
Project objectives from proposal:
1. Using a well-studied Fg isolate (Gz014NY98), investigate natural variation
in morphological features of Fg and maize tissue, levels of mycotoxins and maize defense compounds accumulated in infected tissue, and expression of maize and fungal marker genes among 14 New York grain corn hybrids along the progression of Fg infection. Three of these characteristics (i.e. disease severity, mycotoxin accumulation level, and rate of infection spread) are chosen to define resistance levels, because they are directly related to practical needs in Fg control. The other traits are selected based on previous publications (elaborated in Approach and Methods, and Literature Review).
2. Repeat the natural variation screen with 12 other Fg isolates, and compile these observations and quantifications into a broadly applicable Fg resistance evaluation and prediction system by testing for consistent pairwise correlation between traits across plant and fungal genotypes. Traits consistently correlated with the resistance-defining characteristics are hypothesized to be the predictive characteristics.
3. Verify the accuracy of this system by measuring the predictive and resistance-defining characteristics of field-collected grain corn seedlings infected with natural Fg isolates, and comparing the predicted and the experimentally measured resistance levels.