Evaluation of Claviceps purpurea isolates on wheat reveals complex virulence and host susceptibility relationships

Ergot of cereals is caused by the fungus Claviceps purpurea, and results in yield loss and downgrading of grain contaminated with ergot bodies which contain toxic alkaloids. Some wheat lines have been shown to be resistant to ergot isolates from Manitoba, but we don’t know if these wheat lines are resistant to isolates of the pathogen from other parts of Canada or the world. The aim of this work was to determine if ergot isolates from different regions of the Canadian Prairies or the United Kingdom would cause similar disease severity on eight wheat lines which differ in their resistance to the ergot pathogen. Forty one ergot isolates from Canadian and United Kingdom collections were inoculated onto eight wheat genotypes (durum wheat lines ‘Melita’, ‘Kyle’, and 9260B-173A, and hexaploid spring wheat lines ‘Cadillac’, ‘Vista’, ‘Kenya Farmer’, ‘Lee’ and HY630). Differences in disease severity were observed among the wheat lines. Lines such as 9260B-173A had low disease severities when tested against most of the ergot isolates while others, such as ‘Cadillac’, had high disease severities. Differences in disease severity on the wheat lines did occur depending on which ergot isolate they were tested against. Ergot isolates from different regions of the Canadian Prairies or the United Kingdom did differ in the amount of disease they caused on the eight wheat genotypes. This information is important to wheat breeders who breed for resistance to ergot because it shows that they need to select the proper ergot isolates for testing to be sure that new wheat lines will be resistant to ergot in their areas they are grown.