Continue monitoring Leptosphaeria maculans populations following the introduction of resistant genes Rlm2, Rlm4 and Rlm7 for effective resistance deployment on the Canadian Prairies

Project Summary

Overview

Genetic resistance plays an important role in blackleg management on canola, but effective deployment of specific resistance (R) genes depends on the knowledge of pathogen race structure. Monitoring L. maculans populations on the Prairies since 2010 has revealed the changes of several avirulence (Avr) genes. This has prompted the introduction of new canola varieties carrying the R genes Rlm2, Rlm4 and/or Rlm7 recently. It is generally believed that the pathogen population will adapt to the newly-introduced R genes, resulting in erosion in resistance over time.

This project will build on the progress of the ‘Monitoring the race dynamics of Leptosphaeria maculans for effective deployment and rotation of resistance genes for sustainable management of blackleg of canola in western Canada‘ project.

Purpose

The proposed project is intended to provide canola industry and breeders updated information on pathogen race changes (Avr profile). It will also attempt to address the need to improve the tool with Avr profiling and assess the impact of lowered blackleg levels (by resistance) on reducing seed contamination by the pathogen inoculum.

The information on the prevalence and distribution of L. maculans races can help breeders to determine effective regimes of R genes to be used in new canola varieties. For agronomists, the information will help recommendations for optimal rotation of resistant canola cultivars. The study may also identify the emergence of virulent pathogen races as did in the previous study, providing breeders and industry early warning before significant resistance erosion resulting from the defeat of Rlm2, Rlm4 or Rlm7.

Objective

The main objectives are:

• Conducting annual analysis of L. maculans race structure on the Prairies based on Avr profiling to detect any major shift in the pathogen virulence.

• To develop KASP markers for the detection of AvrLm10 and AvrLmS-Lep2 in L. maculans.
• To assess the impact of newly introduced R genes on blackleg in relation to the Avr profile of pathogen at different locations.

The information on L. maculans race structure is frequently sought after by all stakeholders. Ultimately canola producers are the biggest beneficiary of this study because the information can help guide the deployment and rotation of canola cultivars carrying effective R genes against blackleg. Effective use of cultivar resistance, in combination with other management practices such as on-farm scouting and extended crop rotation will help mitigate the impact of blackleg on the Prairies.