First report of clubroot (<i>Plasmodiophora brassicae</i>) on canola in Ontario

Al-Daoud, Fadi; Moran, M.; Gossen, B. D.; McDonald, Mary Ruth

doi:10.1080/07060661.2017.1393696

Cited by 19 publications

(9 citation statements)

References 8 publications

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“…3). Clade 2 consisted mainly of collections from canola in Prince Edward Island, Ontario [18], and North Dakota, USA, from sites where the pathotype has changed. Three of the five strains from China clustered together in Clade 3.…”

Section: Resultsmentioning

confidence: 99%

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Whole-genome DNA similarity and population structure of Plasmodiophora brassicae strains from Canada

Sedaghatkish

Gossen

et al. 2019

BMC Genomics

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Background Clubroot is an important disease of brassica crops world-wide. The causal agent, Plasmodiophora brassicae, has been present in Canada for over a century but was first identified on canola (Brassica napus) in Alberta, Canada in 2003. Genetic resistance to clubroot in an adapted canola cultivar has been available since 2009, but resistance breakdown was detected in 2013 and new pathotypes are increasing rapidly. Information on genetic similarity among pathogen populations across Canada could be useful in estimating the genetic variation in pathogen populations, predicting the effect of subsequent selection pressure on changes in the pathogen population over time, and even in identifying the origin of the initial pathogen introduction to canola in Alberta. Results The genomic sequences of 43 strains (34 field collections, 9 single-spore isolates) of P. brassicae from Canada, the United States, and China clustered into five clades based on SNP similarity. The strains from Canada separated into four clades, with two containing mostly strains from the Prairies (provinces of Alberta, Saskatchewan, and Manitoba) and two that were mostly from the rest of Canada or the USA. Several strains from China formed a separate clade. More than one pathotype and host were present in all four Canadian clades. The initial pathotypes from canola on the Prairies clustered separately from the pathotypes on canola that could overcome resistance to the initial pathotypes. Similarly, at one site in central Canada where resistance had broken down, about half of the genes differed (based on SNPs) between strains before and after the breakdown. Conclusion Clustering based on genome-wide DNA sequencing demonstrated that the initial pathotypes on canola on the Prairies clustered separately from the new virulent pathotypes on the Prairies. Analysis indicated that these ‘new’ pathotypes were likely present in the pathogen population at very low frequency, maintained through balancing selection, and increased rapidly in response to selection from repeated exposure to host resistance.

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Section: Resultsmentioning

confidence: 99%

“…The source of the initial infection on canola has never been determined. Following its initial identification in Alberta, clubroot on canola was identified in Manitoba in 2009 [16], in Saskatchewan in 2010 [17], and in Ontario in 2016 [18].…”

Section: Introductionmentioning

confidence: 99%

Whole-genome DNA similarity and population structure of Plasmodiophora brassicae strains from Canada

Sedaghatkish

Gossen

et al. 2019

BMC Genomics

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“…In the Canadian Prairies, clubroot was first identified on canola in 2003, in a dozen fields near Edmonton, Alberta (Tewari et al 2005). The disease has since then spread throughout central Alberta (Strelkov et al 2015) and has also been confirmed in canola fields in Saskatchewan (Ziesman et al 2019), Manitoba (Froese et al 2019), Ontario (Al-Daoud et al 2018) and North Dakota (Chittem et al 2014). Plasmodiophora brassicae can produce large numbers of resting spores, which can survive in the soil for up to 20 years (Wallenhammar 1996).…”

Section: Introductionmentioning

confidence: 97%

Plasmodiophora brassicae infection threshold – how many resting spores are required for infection of canola (Brassica napus)

Zahr

Yang

Dijanovic

et al. 2021

Preprint

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Clubroot, caused by Plasmodiophora brassicae, is an important disease of canola and other brassica crops. Improved understanding of host and pathogen biology is frequently useful in guiding management strategies. In order to better understand infection thresholds, seven-day old seedlings of canola cultivar Westar were inoculated with serially diluted concentrations of P. brassicae resting spores. Controlled soil and plant inoculation assays were performed and the plants maintained in a greenhouse for 42 days and clubroot disease severity evaluated visually. Clubroot symptoms were observed in soils containing as low as one spore/mL soil and on plants inoculated with as few as ≤ 100 resting spores. These thresholds were lower than any previously reported. The results indicated the importance of highly sensitive detection methods for P. brassicae diagnosis and quantification methods for clubroot risk prediction in soils. Furthermore, these results highlighted the low probability of obtaining P. brassicae single spore isolates.

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“…For both swede midge and clubroot, winter canola offers a potential solution to maintain or expand canola acreage in Ontario. For instance, clubroot resistance genes have been identified in European winter canola cultivars (Rahman et al 2011;Rahman et al 2014;Aigu et al 2020), and while this disease was first reported on Ontario spring canola in 2016 (Al-Daoud et al 2018), it has yet to be observed on winter canola (M. Moran, personal communication). Similarly, it has been hypothesized that the earlier transition to reproductive growth in winter canola relative to its spring counterpart may allow it to avoid the peak period of swede midge activity and thus, the damage to meristematic tissue that accompanies larval feeding (Chen et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Effect of seeding date on winter canola (Brassica napus L.) yield and oil quality in southern Ontario

et al. 2021

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Winter canola or winter oilseed rape (Brassica napus L.) is not commonly grown in Canada. While winter oilseed rape is the dominant growth form in Europe, Canadian canola production is dominated by spring types in western Canada. Research conducted in the 1980s indicated that the environmental conditions in southern Ontario are well suited to the production of winter canola. Since then, however, interest in the crop has ebbed and little to no research has been conducted on the agronomic issues that potentially limit its adoption in the province. The objective of this research was to identify an optimal seeding date for winter canola in southern Ontario. Three winter canola hybrids were evaluated across five seeding dates ranging from early September to late October. Results established the first two weeks of September as the optimal seeding period for winter canola in southern Ontario. Seeding winter canola during this period, such that greater than 600 GDD could be accumulated before the first fall frost, not only reduced winterkill to approximately 20% but also maximized yield potential and ensured optimal oil quality. Winter canola showed great potential for production in southern Ontario and its addition to current crop rotations would diversify and enhance crop production practices in this portion of the province.

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First report of clubroot (Plasmodiophora brassicae) on canola in Ontario

Cited by 19 publications

References 8 publications

Whole-genome DNA similarity and population structure of Plasmodiophora brassicae strains from Canada

Whole-genome DNA similarity and population structure of Plasmodiophora brassicae strains from Canada

Plasmodiophora brassicae infection threshold – how many resting spores are required for infection of canola (Brassica napus)

Effect of seeding date on winter canola (Brassica napus L.) yield and oil quality in southern Ontario

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