Comparison of ELISA for Fusarium, visual screening, and deoxynivalenol analysis of Fusarium head blight for barley field nurseries

Breeding for resistance to Fusarium head blight {FHB; caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein) Petch]} is complicated because there is no accurate method for quantifying the disease organism. Most breeders rely on visual scoring for FHB and deoxynivalenol (DON) analysis to assess disease severity, but both DON and visual scoring are subject to error. The objective of this study was to compare a Fusarium-specific quantifiable enzyme-linked immunosorbent assay (ELISA) to DON and visual assessment of FHB. A doubled-haploid mapping population was grown in two environments and breeding lines in the North American Barley Scab Evaluation Nursery (NABSEN) were grown at four locations. Both experiments used a randomized complete block design and were analyzed for Fusarium by ELISA, DON, and visually scored for FHB. ELISA values for the doubled-haploid lines were consistent over years, and lines that were low in ELISA were also Iow in DON. Broad sense heritability was greater for ELISA (0.48) than DON (0.19) or visual scores of disease (0.29) in the NABSEN study. Numbers of locations and replications necessary to screen for disease were calculated for ELISA, DON, ancl FHB. ELISA required one-third to one-fourth as many replications and locations as did DON or FHB. Temperature and osmotic potential had little effect on mycelial antigen used for ELISA in vitro, but both affected DON. ELISA is a practical alternative to combined visual scores and DON analysis for breeders interested in improving FHB resistance.