Understanding the mechanisms for race-specific and non-specific resistance for effective use of cultivar resistance against blackleg of canola in western Canada

The Challenge

The pathogen shift of blackleg in canola has been studied for several years due to resistance breakdown. Based on the Avr-gene profile and R genes employed commercially, few canola cultivars would be expected to resist blackleg sufficiently in western Canada, yet severe disease damage is not observed in all regions. Quantitative resistance is suspected to be the main resistance type in canola cultivars, but little is understood about its mechanisms.

The Project

Provide science-based guidelines for optimal use of different types of host resistance against blackleg disease in canola. R-rated commercially available canola cultivars will be analyzed to determine the type of resistance, along with their response to different Avr genes. Race-specific and non-specific blackleg resistance will be observed during the infection process to differentiate between various key mechanisms associated with the resistance. Finally, environmental factors affecting the expression/efficacy of resistance will be monitored to determine if conditions affect resistance expression.

The Results

Increased understanding of race non-specific resistance to blackleg in Canadian canola cultivars. The mode of action associated with one of the cultivars with nonspecific resistance is related to programmed cell death, which can generate reactive oxygen species. Major-gene resistance, as shown by Rlm1, have different molecular mechanisms of defense response, including up-regulation of genes involved in jasmonic acid and salicylic acid pathways of canola plants.

Grower Benefits

A better understanding behind the mechanism of blackleg resistance will help prolong the effectiveness and use of commercially available resistant genetics in the field.