Plasmodiophora brassicae infection threshold—how many resting spores are required for generating clubroot galls on canola (Brassica napus)

2022 ◽  
Author(s):  
Kher Zahr ◽  
Yalong Yang ◽  
Alian Sarkes ◽  
Snezana Dijanovic ◽  
Heting Fu ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae ◽  
Resting Spores

scholarly journals Greenhouse Evaluation of Clubroot Resistant-Brassica napus cv. Mendel and Its Efficacy Concerning Virulence and Soil Inoculum Levels of Plasmodiophora brassicae

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 151 ◽  
Author(s):  
Nazanin Zamani-Noor ◽  
Imke Krohne ◽  
Birger Koopmann
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae ◽  
Root Weight ◽  
Susceptible Cultivar ◽  
Clubroot Resistance ◽  
Soil Inoculum ◽  
Resting Spore ◽  
Greenhouse Evaluation ◽  
Major Resistance Gene ◽  
Resting Spores

Clubroot resistance of oilseed rape (OSR) cultivars frequently relies on a major resistance gene originating from cv. Mendel. The efficacy of this resistance was studied in greenhouse experiments using two Plasmodiophora brassicae isolates, which were either virulent (P1(+)) or avirulent (P1) on Mendel. Seeds of clubroot-susceptible cultivar Visby and clubroot-resistant cultivar Mendel were sown in soil mixtures inoculated with different concentrations of resting spores (101, 103, 105, and 107 resting spores/g soil). Clubroot severity, plant height, shoot and root weight as well as resting spore propagation were assessed for each isolate and cultivar separately at four dates after sowing. The OSR cultivars behaved significantly different in the measured parameters. The threshold of inoculum density to cause disease depended strongly on the virulence of the pathogen and susceptibility of the host plant. In Visby grown in soil infested with P1, clubroot symptoms and increases in root weight and the number of propagated resting spores occurred at inoculum levels of 101 resting spores and higher, whereas Mendel was not affected in soils under the three lowest inoculum densities. In contrast, the P1(+) isolate led to earlier and more severe symptoms, heavier galls, and a significantly higher number of new resting spores in both cultivars.

scholarly journals Isolation and Variation in Virulence of Single-Spore Isolates of Plasmodiophora brassicae from Canada

Plant Disease ◽  
2008 ◽  
Vol 92 (3) ◽  
pp. 456-462 ◽  
Author(s):  
S. Xue ◽  
T. Cao ◽  
R. J. Howard ◽  
S. F. Hwang ◽  
S. E. Strelkov
Keyword(s):  
British Columbia ◽  
Brassica Napus ◽  
Efficient Method ◽  
Plasmodiophora Brassicae ◽  
Breeding Strategy ◽  
Single Spore ◽  
Susceptible Host ◽  
Significant Difference ◽  
Resting Spores ◽  
Important Disease

Clubroot of crucifers, caused by Plasmodiophora brassicae, is emerging as an important disease of canola (Brassica napus) in Alberta, Canada. Populations of the pathogen often consist of a mixture of different pathotypes. Therefore, a simple and efficient method to isolate single resting spores of P. brassicae was developed, based on serial dilution of spore suspensions. The virulence of 24 single-spore isolates, representing five populations of the pathogen from Alberta, Ontario, and British Columbia, was characterized on the differentials of Williams and Somé et al. Symptoms were rated 6 weeks after inoculation and Fisher's least significant difference (P < 0.05) was used to differentiate resistant from susceptible host reactions. The pathotype composition of P. brassicae in Canada appeared more diverse when single-spore isolates were examined rather than populations of the pathogen. In Alberta, at least three and possibly four pathotypes were identified among the 14 isolates tested, whereas a maximum of only two pathotypes had been reported previously when populations of the pathogen were examined. Pathotype 3 or P2, as classified on the differentials of Williams and Somé et al., respectively, was found to be predominant in the province. The occurrence of other pathotypes at lower frequencies suggests that caution should be used in any breeding strategy, because rare pathotypes of P. brassicae may quickly become predominant if susceptible host genotypes are continuously grown.

Germination of Plasmodiophora brassicae resting spores stimulated by a non-host plant

2005 ◽  
Vol 113 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Hanna Friberg ◽  
Jan Lagerlöf ◽  
Birgitta Rämert
Keyword(s):  
Host Plant ◽  
Plasmodiophora Brassicae ◽  
Resting Spores

scholarly journals Mapping of clubroot (Plasmodiophora brassicae) resistance in canola (Brassica napus)

2015 ◽  
Vol 65 (3) ◽  
pp. 435-440 ◽  
Author(s):  
H. Zhang ◽  
J. Feng ◽  
S.-F. Hwang ◽  
S. E. Strelkov ◽  
I. Falak ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae

scholarly journals Endosphere microbiome comparison between symptomatic and asymptomatic roots of Brassica napus infected with Plasmodiophora brassicae

PLoS ONE ◽  
2017 ◽  
Vol 12 (10) ◽  
pp. e0185907 ◽  
Author(s):  
Ying Zhao ◽  
Zhixiao Gao ◽  
Binnian Tian ◽  
Kai Bi ◽  
Tao Chen ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae

The life history of Plasmodiophora brassicae Woron

1972 ◽  
Vol 180 (1058) ◽  
pp. 103-112 ◽  
Keyword(s):  
Life History ◽  
Root Hair ◽  
Plasmodiophora Brassicae ◽  
Root Hairs ◽  
Secondary Phase ◽  
Tissue Cultures ◽  
Resting Spore ◽  
Resting Spores ◽  
Seedling Roots ◽  
History Of

Resting spore germination and the root hair stages of the life history of Plasmodiophora brassicae were studied in stained preparations of infected Brassica rapa seedling roots. Naked protoplasts, usually possessing two unequal flagella, were released from resting spores through a small circular pore. They penetrated the root hairs of B. rapa and there developed into plasmodia which, after becoming multinucleate, cleaved to form zoosporangia con­taining incipient zoospores. Biflagellate zoospores were released from root hair zoosporangia and fused in pairs, although karyogamy did not occur. The resulting binucleate zoospores infected the cortical dells of B. rapa to form binucleate plasmodia, the earliest stages of the secondary phase of the life history. These findings are discussed in relation to previous studies on the life history of P. brassicae in Brassica plants and in Brassica tissue cultures, and a new complete life history, including nuclear fusion in the secondary plasmodium, is suggested for the organism.

Emergence of new virulence phenotypes of Plasmodiophora brassicae on canola (Brassica napus) in Alberta, Canada

2016 ◽  
Vol 145 (3) ◽  
pp. 517-529 ◽  
Author(s):  
Stephen E. Strelkov ◽  
Sheau-Fang Hwang ◽  
Victor P. Manolii ◽  
Tiesen Cao ◽  
David Feindel
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae

scholarly journals Effect of pathogen virulence on pathogenicity, host range and reproduction of Plasmodiophora brassicae, the causal agent of clubroot disease

Plant Disease ◽  
2021 ◽  
Author(s):  
Nazanin Zamani-Noor ◽  
Sinja Brand ◽  
Hans-Peter Soechting
Keyword(s):  
Plasmodiophora Brassicae ◽  
Brassica Species ◽  
Post Inoculation ◽  
Clubroot Disease ◽  
Alopecurus Myosuroides ◽  
Pathogen Virulence ◽  
Iberis Amara ◽  
Thlaspi Arvense ◽  
Resting Spores ◽  
Pathogen Dna

A series of greenhouse experiments was conducted to evaluate the effect of Plasmodiophora brassicae virulence on clubroot development and propagation of resting spores in 86 plant species from 19 botanical families. Plants were artificially inoculated with two isolates of P. brassicae, which were either virulent on clubroot-resistant oilseed rape cv. Mendel (P1 (+)) or avirulent on this cultivar (P1). Clubroot severity and the number of resting spores inside the roots were assessed 35 days post inoculation. Typical clubroot symptoms were observed only in the Brassicaceae family. P1 (+)-inoculated species exhibited more severe symptoms (2 to 10–fold more severe), bigger galls (1.1 to 5.8 fold heavier) and higher number of resting spores than the P1-inoculated plants. Among all Brassica species, Bunias orientalis, Coronopus squamatus and Raphanus sativus were fully resistant against both isolates, while Camelina sativa, Capsella bursa-pastoris, Coincya momensis, Descurainia sophia, Diplotaxis muralis, Erucastrum gallicum, Neslia paniculata, Sinapis alba, S. arvensis, Sisymbrium altissimum, S. loeselii and Thlaspi arvense were highly susceptible. Conringia orientalis, Diplotaxis tenuifolia, Hirschfeldia incana, Iberis amara, Lepidium campestre and Neslia paniculata were completely or partially resistant to P1-isolate but highly susceptible to P1 (+). These results propose that the basis for resistance in these species may be similar to that found in some commercial cultivars, and that these species could contribute to the build-up of inoculum of virulent pathotypes. Furthermore, the pathogen DNA was detected in Alopecurus myosuroides, Phacelia tanacatifolia, Papaver rhoeas and Pisum sativum. It can concluded that the number and diversity of hosts for P. brassicae are greater than previously reported.

Genetic structure of Plasmodiophora brassicae populations virulent on clubroot resistant canola (Brassica napus)

Plant Disease ◽  
2021 ◽  
Author(s):  
Homa Askarian ◽  
Alireza Akhavan ◽  
Leonardo Galindo González ◽  
Sheau-Fang Hwang ◽  
Stephen Ernest Strelkov
Keyword(s):  
Brassica Napus ◽  
Genetic Structure ◽  
Plasmodiophora Brassicae ◽  
Single Spore ◽  
Specific Primers ◽  
Brassica Napus L ◽  
Before And After ◽  
Differential Hosts ◽  
And Migration ◽  
Simple Sequence

Clubroot, caused by Plasmodiophora brassicae Woronin, is a significant threat to the canola (Brassica napus L.) industry in Canada. Clubroot resistance has been overcome in more than 200 fields since 2013, representing one of the biggest challenges to sustainable canola production. The genetic structure of 36 single-spore isolates derived from 12 field isolates of P. brassicae collected before and after the introduction of clubroot resistant (CR) canola cultivars (2005-2014) was evaluated by simple sequence repeat (SSR) marker analysis. Polymorphisms were detected in 32 loci with the identification of 93 distinct alleles. A low level of genetic diversity was found among the single-spore isolates. Haploid linkage disequilibrium and number of migrants suggested that recombination and migration were rare or almost absent in the tested P. brassicae population. A relatively clear relationship was found between the genetic structure and virulence phenotypes of the pathogen as defined on the differential hosts of Somé et al., Williams and the Canadian Clubroot Differential (CCD) set. Although genetic variability within each pathotype group, as classified on each differential system, was low, significant genetic differentiation was observed among the pathotypes. The highest correlation between genetic structure and virulence was found among matrices produced with genetic data and the hosts of the CCD set, with a threshold index of disease of 50% to distinguish susceptible from resistant reactions. Genetically homogeneous single-spore isolates provided a more complete and clearer picture of the population genetic structure of P. brassicae, and the results suggest some promise for the development of pathotype-specific primers.

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