Improving blackleg disease management of Brassica napus from knowledge of genetic interactions with Leptosphaeria maculans^†

^†Contribution to the symposium “Signalling in Plant-Pathogen Interactions” held during the Canadian Phytopathological Society Annual Meeting, 22–25 June 2009, Winnipeg, MB.

Abstract

Leptosphaeria maculans , the cause of blackleg or phoma stem canker of oilseed rape and canola ( Brassica napus ) is becoming a model system for the study of genetic relationships between host and pathogen. Knowledge of this relationship has progressed from the discovery of differential reactions among canola varieties and pathogen isolates to the elucidation of specific resistance genes in the host and the corresponding avirulence genes in the pathogen. The use of a race-specific resistance strategy to manage this disease has been of great value in Canada, Australia and Europe; however, due to the pathogen's propensity to change, new pathotypes or races have been observed to arise rapidly. This paper reviews these developments and discusses applications of this knowledge to applied management of this disease in B. napus .

Résumé: Leptosphaeria maculans, l'agent causal de la jambe noire ou de la nécrose du collet (phoma) chez le colza et le canola (Brassica napus), est en voie de devenir un système modèle pour l'étude des relations génétiques entre l'hôte et l'agent pathogène. Les connaissances associées à cets relation ont progressé, et ce, de la découverte d'interactions différentielles entre les variétés de canola et les isolats de L. maculans jusqu'à l'élucidation des gènes spécifiques de la résistance chez l'hôte et des gènes d'avirulence correspondants chez l'agent pathogène. L'utilisation d'une stratégie faisant appel à la résistance spécifique pour gérer cette maladie a été des plus efficaces au Canada, en Australie et en Europe. Toutefois, à cause de la tendance naturelle de L. maculans à s'adapter nous avons observé l'apparition rapide de nouveaux pathotypes ou de nouvelles races. Cet article passe en revue ces progrès et discute des applications de ces connaissances à la gestion de la maladie chez B. napus.

Keywords:

• blackleg resistance
• gene-for-gene interactions
• oilseed rape
• Phoma lingam

Mots clés:

• interactions gène-à-gène
• Phoma lingam
• résistance à la nécrosse de collet

Acknowledgements

Past support from the Saskatchewan Canola Development Commission and the Alberta Canola Producers Association through the Canola Council of Canada and the Matching Investment Initiative of Agriculture and Agri-Food Canada is gratefully acknowledged by the senior author. Also recognized are the contributions of the Organization for Economic Co-operation and Development's Co-operative Research Programme and the excellent technical work of Mr D. Cross and Ms C. Kirkham. Dr Kutcher is grateful to Dr N. Larkan for a critical review of the manuscript and to the late Dr Roger Rimmer as a mentor and colleague.

Notes

^†Contribution to the symposium “Signalling in Plant-Pathogen Interactions” held during the Canadian Phytopathological Society Annual Meeting, 22–25 June 2009, Winnipeg, MB.