Fusarium head blight and deoxynivalenol from barley in the Maritime Provinces

Abstract

Fusarium Head Blight (FHB) is one of the most devastating agriculture diseases that affects barley worldwide by reducing crop yields and grain quality. The main causal organism of concern in Eastern Canada is the fungal pathogen, Fusarium graminearum. This pathogen inhibits protein synthesis in the seeds, resulting in low yields, and can produce mycotoxins to contaminate the grains. Deoxynivalenol (DON) is the most important mycotoxins as it is toxic to animals and humans. It is important to perform barley disease surveys in the Maritimes as they have ceased in the early 2000s, resulting in a lack of FHB information in these provinces. To further understand the presence of FHB causing species and DON in the Maritime provinces, barley seeds were collected by partners at the Atlantic Grains Council. Seed samples were separated per field to isolate Fusarium species, and a second subsample ground for quantitative-PCR (qPCR) and DON analysis. A total of 336 isolates were collected, the majority being F. graminearum, other species identified were F. poae, F. avenaceum, and F. sporotrichioides. DON concentrations ranged from 0 to 15.6 ppm in each field. Nova Scotia presented the highest disease level based on qPCR of F. graminearum DNA, isolate numbers and DON levels, with less disease presence in New Brunswick and PEI. F. graminearum DNA correlated significantly with DON concentration (R²=0.92). A virulence assay using F. graminearum isolates from each province was performed to observe differences between provincial isolates and to assess visual rating methods. qPCR data did reveal a weak positive correlation with visual severity ratings (R²=0.48). This qPCR assay revealed a rapid and reliable method to evaluate and quantify FHB in barley to be used in future surveys. Correlation results can be used to increase precision in other agronomic studies that aim to reduce FHB severity.