Evaluation of Fusarium Head Blight Resistance in a Canadian Winter Wheat DH population.

Fusarium head blight (FHB) is one of the most devastating diseases of wheat, causing significant reductions in grain yield and end-use quality. Fusarium graminearum is the common causal agent of FHB in North America and the accumulation of the fungal toxin, deoxynivalenol (DON), in grains and the end products is a serious concern for human and animal health. Canadian winter wheat varieties ‘AC Morley’ and ‘Emerson’ have shown notable FHB resistance in the field, but the genetic nature of FHB resistance in these varieties is not well understood. Haplotype analysis for major QTLs (Fhb1, Fhb2 and Fhb5) demonstrated the absence of Sumai 3 resistance, a well known source of FHB resistance, suggesting that ‘AC Morley’ and ‘Emerson’ may carry unique FHB resistance. The objective of this study was to evaluate the FHB reaction in a F1-derived doubled haploid (DH) population from a cross between ‘AC Morley’ and ‘Emerson’.
A population consisting of 99 DH lines was tested in field nurseries at Ottawa and Elora in 2017/18 along with parents and checks. A randomized complete block design was used with three replicates. Field plots were inoculated with a mixture of the isolates of 3ADON and 15ADON chemotypes followed by on-going mist-irrigation treatments. The FHB traits, disease incidence, severity, and visual rating index (VRI = (incidence x severity)/100) were determined. Fusarium damaged kernel (FDK) was estimated by counting the infected kernels in a petri dish containing 400 seed samples harvested from each plot. A sub-sample of 1g of the ground sample was used for DON analysis using the AAFC in-house DON ELISA assay. Plant height was also measured in relation to the FHB traits.
VRI scores ranged from 2.1 to 48.7 where AC Morley scored 38.2 and Emerson scored 8.5 at Ottawa location. VRI scores were low at Elora location with over 80% of the population scoring less than 10 and the highest score was 28.4. Both parents had VRI scores less than 5. A negative correlation (r= 0.24, P < 0.05) was observed between plant height and FHB index at Elora. The percentage of FDK and the level of DON accumulation will be presented. A wide distribution of phenotypic results was observed in the AC Morley/Emerson DH population and transgressive segregation for field resistance was detected. The DH population was genotyped using Wheat 90K Illumina SNP array. A planned analysis of quantitative trait loci (QTLs) for FHB resistance will provide insights into genetic architecture of the resistance in AC Morley and Emerson.