European Journal of Plant Pathology (2016) 145, 559-572

Veronika Ricarová, Joanna Kaczmarek, Stephen E. Strelkov, Jan Kazda, Wolfgang Lueders, Pavel Rysanek, Victor Manolii and Malgorzata Jedryczka (2016)
Quantitative PCR shows propagation of Plasmodiophora brassicae in Swedish long term field trials
European Journal of Plant Pathology 145 (3), 559-572
Abstract: Winter oilseed rape (Brassica napus) is an important crop in the Czech Republic and Poland. Clubroot disease caused by the pathogen Plasmodiophora brassicae is a serious and still-growing problem for oilseed rape growers in both countries. The aim of this study was to evaluate the pathotype composition of P. brassicae populations from the Czech Republic and Poland, according to the three evaluation systems, and to determine soil inoculum loads for representative fields via traditional end-point PCR as well as quantitative PCR analysis. There were considerable differences between the populations of P. brassicae from both countries, and the number of pathotypes varied depending on the evaluation system and the threshold used to distinguish susceptible vs. resistant plant reactions. This is the first study comparing the effect of different thresholds. Using an index of disease (ID) of 25 % to distinguish susceptible vs. resistant reactions, there was a total of seven pathotypes identified based on the differentials of Williams, five with the system of Somé et al., and 18 with the European Clubroot Differential (ECD) set. However, based on a threshold of 50 %, there were nine pathotypes according to the evaluation system by Williams, four based on the differentials of Somé et al., and 15 with the ECD set. Changing of the thresholds led to the reclassification of some pathotypes. Several pathotypes were common in both countries. High amounts of pathogen DNA were found in many of the field soils analysed by quantitative PCR. There was a weak correlation between soil pH and infestation of P. brassicae for the Polish soils.
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Database assignments for author(s): Malgorzata Jedryczka, Stephen E. Strelkov, Joanna Kaczmarek, Veronika Ricarová

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plasmodiophora brassicae	Rape/canola (Brassica napus)	Czech Republic
	Plasmodiophora brassicae	Rape/canola (Brassica napus)	Poland