Towards adaptation of a detached head assay for measuring resistance to initial infection (Type 1

Citation

Pordel P, Ryabova D, Goyal RK, Chatterton S, Kovalchuk I, Foroud NA. Towards adaptation of a detached head assay for measuring resistance to initial infection (Type I resistance) by Fusarium graminearum in wheat. 6th Canadian Workshop of Fusarium Head Blight, Ottawa ON, CANADA, November 20-22, 2016. p.83

Résumé

Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum and related species, results in economic loss and grain quality reduction. Disease resistance is typically reported as FHB index, which is a combined measure of incidence (percentage of diseased heads) and severity (percentage of diseased spikelets within diseased heads). FHB index, evaluated through spray or grain spawn inoculation, provides a measure of resistance that is sometimes correlated with resistance to initial infection (Type 1 resistance). However, it does not give an accurate measurement of resistance to initial infection because the value of FHB index is influenced by other forms of resistances, such as disease spread (Type 2 resistance). Disease incidence can be equated to some extent with Type 1 resistance, but a lack of uniform exposure of heads within a plant or a plot affects the reliability and reproducibility of results. Greenhouse disease evaluations offer a higher level of control, but do not eliminate the variability inherent to spray inoculation methods. We are modifying a detached head assay, which we are combining with histological assessments in an effort to establish an improved protocol to assess the mechanisms of Type 1 resistance. This method will be employed to assess the role of hormone signalling in the wheat response to Fusarium graminearum.