Elevated CO 2 Can Worsen Fusarium Head Blight Disease Severity in Wheat but the Fhb1 QTL Provides Reliable Disease Resistance.

Fusarium head blight (FHB) is a destructive fungal disease of wheat that causes significant economic loss due to lower yields and the contamination of grain with fungal toxins (mycotoxins), particularly deoxynivalenol (DON). FHB disease spread and mycotoxin contamination has been shown to worsen at elevated CO, therefore, it is important to identify climate-resilient FHB resistance. This work evaluates whether wheat with the quantitative trait locus (QTL), the most widely deployed FHB resistance locus in wheat breeding programs, provides reliable disease resistance at elevated CO. Near-isogenic wheat lines (NILs) derived from either a highly FHB susceptible or a more FHB resistant genetic background, with or without the QTL, were grown in growth chambers at ambient (400 ppm) and elevated (1000 ppm) CO conditions. Wheat was inoculated with and evaluated for FHB severity. At elevated CO, the NILs derived from more FHB-resistant wheat had increased disease spread, greater pathogen biomass and mycotoxin contamination, and lower rates of DON detoxification; this was not observed in wheat from a FHB susceptible genetic background. The QTL was not associated with increased disease severity in wheat grown at elevated CO and provided reliable disease resistance.