Pathotypes of Plasmodiophora brassicae causing damage to oilseed rape in the Czech Republic and Poland

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.

Variation of Glucosinolate Contents in Clubroot-Resistant and -Susceptible Brassica napus Cultivars in Response to Virulence of Plasmodiophora brassicae

“…Physiological specialization has long been known to occur in P. brassicae [ 6 ], with pathotypes of the pathogen varying in their ability to infect specific host crops. Previous studies in European countries have revealed variations in pathotype distributions across different countries [ 7 , 8 , 9 , 10 ]. Pathotype 1 (P1) and Pathotype 3 (P3) or ECD 16/31/31 and 16/14/31 as classified on the differentials of Somé et al [ 11 ] and the European Clubroot Differential [ 12 ], respectively, are predominant in central Europe.…”

Molecular characterization of disease resistance in Brassica juncea – The current status and the way forward

“…Infection in oilseed brassicas has been reported worldwide (Saharan, 1993;Bhattacharya et al, 2014;Řičařová et al, 2016;Xue et al, 2017), as well as in B. juncea vegetables in China (Xue et al, 2017) and B. juncea crops in India (Chattopadhyay and Bagchi, 1989;Bhattacharya et al, 2014). A major first epidemic of clubroot occurred in the early 1980s in India (Laha et al, 1985), where disease incidence ranged from 30% on B. juncea to 70% on B. rapa (Chattopadhyay and Bagchi, 1989).…”

“…Infection in oilseed brassicas has been reported worldwide (Saharan, 1993; Bhattacharya et al, 2014; Řičařová et al, 2016; Xue et al, 2017), as well as in B . juncea vegetables in China (Xue et al, 2017) and B .…”

Influence of Soil-Borne Inoculum of Plasmodiophora brassicae Measured by qPCR on Disease Severity of Clubroot-Resistant Cultivars of Winter Oilseed Rape (Brassica napus L.)

“…The 25.5 Mb genome sequence of P. brassicae single spore isolate e3 was presented for the first time a few years ago [7]. Internationally, the spread of P. brassicae has increased rapidly in spring OSR (canola) in Canada [8,9], North Dakota [10], Finland [11] and Latin-America [12], and in winter OSR in the UK [13], Germany [14], Poland, [15,16], Czech Republic [17], China [18], and other countries.…”