Mapping Ergot Resistance in Durum Wheat

Ergot, caused by the ascomycete Claviceps purpurea (Fr.) Tul., has emerged as an important disease of durum wheat in Canada. Ergot contamination has increased since 2000 to as high as 50% of wheat lots being downgraded at Alberta grain elevators in 2013. Ergot sclerotia contain toxic alkaloids, which can cause severe health problems and even death if ingested. The durum wheat line 9260B-173A, identified as a source of ergot resistance, was studied in an AC Avonlea/9260B-173A recombinant inbred line (RIL) population. Subsequently, a doubled haploid (DH) population was studied, AC Avonlea/RIL-3, where RIL-3 was an ergot resistant line from the AC Avonlea/9260B-173A population. These populations were phenotyped for honeydew and sclerotial production by inoculation of florets with a 10⁴ conidia per ml suspension of six C. purpurea isolates in growth chamber experiments. Genotyping was performed with the wheat 90K Infinium SNP beadchip assay and with the KASP SNP assay. Linkage maps were developed for each population and QTL analysis conducted. A major QTL on chromosome 2A reduced honeydew production and percent infected florets (i.e. sclerotia number). Another major QTL on chromosome 5B reduced sclerotia mass per spike, percent infected florets, and mean sclerotia mass. A third QTL on chromosome 1B reduced mean sclerotia mass. These results will enable marker-assisted selection of ergot resistance and guide future genetic research.