Characterization of the new strains of the clubroot pathogen in Alberta

The Challenge

New strains of Plasmodiophora brassicae have emerged, which are able to overcome resistance in “clubroot resistant” canola.

The Project

Identify and characterize the strains of P. brassicae that can overcome resistance and identify genetic resources that are not prone to this resistance breakdown. Develop molecular markers to distinguish P. brassicae strains and possibly identify pathogen populations based on pathotype.

The Results

The Canadian Clubroot Differential (CCD) set was created which includes the differentials of Williams and Somé et al., selected hosts of the European Clubroot Differential Set, and the Brassica napus cultivars ‘Brutor’, ‘Mendel’, ‘Westar’ and ‘45H29’. A total of 17 pathotypes were detected using the CCD set  compared to with five pathotypes using the system of Williams and two with the system of Somé et al., suggesting that the CCD set has a greater differentiating capacity. Additionally, a molecular marker was also developed to identify pathotype 5X which was the first of the resistance-breaking pathotypes of P. brassicae to be identified in Canada.

Grower Benefits

Shifts in the populations of the clubroot pathogen can now be tracked. This will help breeders determine which resistant genetics are required in commercially available canola to manage clubroot.