Growing Forward 2: Canola Disease Management Tools for the Prairies - Blackleg and Sclerotinia

Date: March 2018
Term: 5 years
Status: Completed
Researcher(s): H. Borhan, L. Buckwaldt, D. Hegedus – Agriculture and Agri-Food Canada, R. Belanger – University of Laval, D. Fernando, G. Li – University of Manitoba S. Strelkov – University of Alberta
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a

Project Summary

Surveillance monitoring has shown that blackleg is again increasing in incidence and severity in western Canada, in part due to breakdown of a widely used major resistance gene. Sclerotinia stem rot is also a serious disease for canola growers, particularly in severe wet and cool growing seasons. Several research projects have addressed these concerns, with the outcomes helping to pave the way for new tools and technology, advancements in disease gene screening and new sources of disease resistance genetics. Farmers benefit directly from the research by being able to understand and manage these diseases in their own fields, and maximizing productivity through access to new and improved disease resistant canola cultivars.

Blackleg Risk Mitigation plan to protect international trade

Blackleg historically has caused significant economic loss in Canada and recently has been a trade issue between China and Canada as China is concerned that imported infected seed and dockage from Canada will transmit the disease to oilseed rape in China. This research has directly addressed China’s phytosanitary concern by mitigating risk of introduction of blackleg from Canadian canola by reducing disease in Canada’s canola crop. Furthermore, this research will provide significant economic return to Canada’s canola industry by reducing crop loss and maximizing productivity through access to new and improved disease resistant canola cultivars.

The 2016 MOU between Canada and China commits Canada to reducing blackleg in the field to mitigate risk for China. The research projects and KTT generated from the GF2 AgriInnovation Program Stream have a direct impact on the success of the MOU.

Several research projects have addressed these concerns, with the outcomes helping to pave the way for new tools and technology, advancements in disease gene screening and new sources of disease resistance genetics. The outcomes are as follows:

1. Rapid field diagnostics test for blackleg disease.

China requested that Canada develop a rapid “in-field” test to identify blackleg races present on the canola stubble. The PCR biomarkers, which were developed as part of this project were shared with public and private pathology labs across western Canada. Four labs now have the markers for commercial evaluation. When growers detect significant amounts of blackleg in their field they may now send stubble samples to pathology labs for genetic testing. The pathology lab will then provide the grower with information on the specific races of blackleg in their field. This will enable canola growers to make informed decisions about choosing the appropriate blackleg resistance in their canola variety that best matches the profile of the blackleg strain in the field. This is an important tool for managing blackleg in the field and addresses a concern of a major trading partner.

2. Surveillance and Identification of blackleg pathogen population in Western Canada.

A stronger understanding of blackleg pathogen population across Western Canada was gained, which will help determine where to deploy specific varieties and R-genes to match the population. This will help to increase the durability of resistance genes and better manage the disease.

3. Identification of new sources and genes for blackleg resistance.

More than 1,100 B. napus and B. rapa accessions are characterized for the profile of known Rlm genes (resistance to blackleg), an invaluable resource for canola breeding programs. Several novel blackleg resistance genes were identified, which can be used by seed companies to improve their genetic base. Preliminary mapping conducted on one of these lines support presence of a novel broad spectrum R gene against blackleg disease. A total of 58 lines with quantitative (adult plant) resistance to blackleg disease were identified and presence of adult plant resistance (APR) was confirmed. APR against blackleg disease of canola is a durable form of resistance and protects canola against the blackleg infection. Also, the first in-depth characterization of Brassicaceae AQPs (aquaporins) highlights transport mechanisms and related physiological processes that could be exploited in breeding programs of sustainable stress tolerant crops.

4. Development of Blackleg resistance gene labels.

The durability of some R genes used within commercial cultivars is now understood. This helped form the foundation for major gene resistance labels now used in blackleg resistance identification. Producers can now choose varieties with R genes that are durable to the specific blackleg races. Australia and Europe have used these labels to enable producers to choose the best gene that is most effective against the blackleg race present in their field. China has recognized that this was a gap in our risk mitigation plan and this research has provided background to develop the gene labelling model and provides the information to producers in an easy to use fashion. This will also play a significant role in reducing blackleg in the field in Canada, and assist breeders in advancing cultivar resistance and durability.

5. Development of a blackleg yield loss model.

Producers can now estimate the amount of yield loss from blackleg in their canola fields. This is a key model that highlights the negative impacts of the disease and the economic constraints it can place on a crop. Being able to show the economic and agronomic impact of the disease to producers helps further showcase why blackleg is an important disease to manage on farm.

Using the yield loss model on the blackleg infested canola acres in western Canada shows that producers and industry have lost $500 million in revenue annually in the past several years. Return on investment for this research is significant if you consider direct loss to industry and potential economic impact to Canada if canola trade with China is halted. Key KTT tools include the western Canadian blackleg survey, the Blackleg Scouting Video, www.blackleg.ca, and the development of the Blackleg Steering Group.

Advancing Sclerotinia Resistance

Sclerotinia stem rot is a serious disease for canola growers, particularly in wet and cool growing seasons, with yield losses estimated at $1.7 billion in 7 of the last 14 crop years. Although fungicide application, currently the only option, can reduce disease severity, financial returns are not guaranteed, since it is difficult to predict which fields need treatment. The outcomes of this research include the identification of new sclerotinia resistant B. napus lines, the development of new protocols and genome sequencing and screening. These outcomes will help industry and farmers improve management of this disease in canola, and provide significant economic return to Canada’s canola industry by reducing crop loss. The outcomes are as follows:

6. Identification and characterization of new isolates, proteins, genes/sequencing for sclerotinia resistance.

Although sclerotinia resistance is a very rare trait, researchers have successfully generated B. napus lines with high levels of sclerotinia resistance, and identified several well- characterized S. sclerotiorum isolates for selecting resistance in breeding lines. The new genetic material of B. napus is the best source of sclerotinia resistance available to plant breeders both in Canada and internationally. The development of linkage maps and molecular markers associated with sclerotinia resistance, along with the set of 17 well- characterized sclerotinia isolates are needed for development of canola varieties that hold up against the pathogen population in western Canada, with the first resistant varieties expected to be available to growers in the next 2-3 years.

The discovery of new S. sclerotiorum proteins allowed researchers to catalogue for the first time the entire suite of genes deployed during each stage of the infection on canola, and contributed to an international consortium of Australian, US, European and Canadian researchers to sequence the S. sclerotiorum genome, which was published and deposited in a public database. A new international consortium is now comparing the genomes of S. sclerotiorum isolates from around the world to provide information on virulence and crop specificity.

7. Development of Standard Protocol for assessing sclerotinia resistance in canola.

A new ‘stem test’ protocol for testing of canola varieties with a claim of sclerotinia resistance was adopted by the Western Canadian Canola/Rapeseed Recommending Committee (WCC/RRC) in 2015. Most canola breeders are now using the sclerotinia stem test to ensure potential new varieties meet the requirements of WCC/RRC.

Full Report PDF: Canola Disease Management Tools for the Prairies - Blackleg and Sclerotinia