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Identification of Sources of Resistance to Blackleg (Leptosphaeria maculans) in a Brassica napus Germplasm Collection

S. Mansouripour and L. E. del Río Mendoza

May 2017

Research

The increased prevalence of strains of pathogenicity group 4 of Leptosphaeria maculans, causal agent of blackleg, represents a serious threat to the canola (Brassica napus L.) industry in North Dakota, a state that contributes >85% of U.S. canola production. The objective of this study was to identify sources of resistance to PG-4 in a collection of 559 B. napus plant introduction materials (PIs). Replicated trials were conducted twice in the greenhouse using a mixture of five PG-4 isolates to evaluate the reaction at seedling stage; then, an elite group of PIs was evaluated in replicated field trials between 2014 and 2016 at Langdon, ND, using a combination of lab-produced inoculum and blackleg-infested canola residues. Combined analysis of field data indicated three PIs had on average 73 to 80% less (P < 0.05) internal stem tissue discoloration than the commercial hybrids used as the controls. These PIs could be used in canola breeding programs as good sources of resistance against PG-4; in addition, efforts should be made to characterize the resistance they carry.

doi:10.1094/PHP-02-17-0011-RS

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