Methods to isolate and maintain clubroot for improved resistance screening and labeling

Project Summary

Clubroot is an important disease of canola caused by the pathogen Plasmodiophora brassicae. Disease management relies heavily on the planting of resistant canola varieties. Unfortunately, clubroot resistance screening and labeling are hindered by the fact that the pathogen cannot be cultured outside of a host plant, and hence must be maintained and increased in living plants.

Reproduction on these hosts can cause shifts in the virulence of the pathogen, so that breeders testing for resistance in a greenhouse may actually be using strains of P. brassicae that no longer represent what is found in the field. Moreover, because the recovery of single-spores isolates of the clubroot pathogen is difficult and time-consuming, “field isolates” often have to be used for resistance screening. These field isolates are usually heterogeneous and may consist of pathotype mixtures, producing inconsistent or fluctuating results.

The main goal of this project is to improve the effectiveness and reliability of clubroot resistance screening and labelling through two primary objectives:

(1) to develop best practices to maintain clubroot isolates in planta to avoid virulence shifts.

(2) to optimize microlaser technology as a fast and efficient way to isolate single-spore isolates for characterization and distribution.

The work will contribute to efforts by the Clubroot Steering Committee to introduce a sequential approach to labeling canola cultivars based on their ability to prevent infection by the prevalent and/or most significant pathotypes of P. brassicae in western Canada.

The outcomes of this research will facilitate informed decision-making by growers, enable more accurate information on the clubroot response of different canola varieties, and help to improve clubroot management.