scholarly journals Virulence Spectrum of Single-Spore and Field Isolates of Plasmodiophora brassicae Able to Overcome Resistance in Canola (Brassica napus)

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Homa Askarian ◽  
Alireza Akhavan ◽  
Victor P. Manolii ◽  
Tiesen Cao ◽  
Sheau-Fang Hwang ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Confidence Interval ◽  
Plasmodiophora Brassicae ◽  
Large Collection ◽  
Single Spore ◽  
Brassica Napus L ◽  
Clubroot Resistance ◽  
Field Isolates ◽  
Virulence Spectrum ◽  
Important Disease

Clubroot, caused by Plasmodiophora brassicae Woronin, is an important disease of canola (Brassica napus L.) that is managed mainly by planting clubroot-resistant (CR) cultivars. Field isolates of P. brassicae can be heterogeneous mixtures of various pathotypes, making assessments of the genetics of host–pathogen interactions challenging. Thirty-four single-spore isolates were obtained from nine field isolates of the pathogen collected from CR canola cultivars. The virulence patterns of the single-spore and field isolates were assessed on the 13 host genotypes of the Canadian Clubroot Differential (CCD) set, which includes the differentials of Williams and Somé et al. Indices of disease (IDs) severity of 25, 33, and 50% (±95% confidence interval) were compared as potential thresholds to distinguish between resistant and susceptible reactions, with an ID of 50% giving the most consistent responses for pathotype classification purposes. With this threshold, 13 pathotypes could be distinguished based on the CCD system, 7 on the differentials of Williams, and 3 on the hosts of Somé et al. The highest correlations were observed among virulence matrices generated using the three threshold IDs on the CCD set. Genetically homogeneous single-spore isolates gave a clearer profile of the P. brassicae pathotype structure. Novel pathotypes, not reported in Canada previously, were identified among the isolates. This large collection of single-spore isolates can serve as a reference in screening and breeding for clubroot resistance.

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.

Variation for virulence on Brassica napus L. amongst Plasmodiophora brassicae collections from France and derived single‐spore isolates

1996 ◽  
Vol 45 (3) ◽  
pp. 432-439 ◽  
Author(s):  
A. SOME ◽  
M. J. MANZANARES ◽  
F. LAURENS ◽  
F. BARON ◽  
G. THOMAS ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae ◽  
Single Spore ◽  
Brassica Napus L

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.

Seed treatment of canola (Brassica napus) with the endomycorrhizal fungus Piriformospora indica does not reduce clubroot

2020 ◽  
Author(s):  
Afsaneh Sedaghatkish ◽  
Bruce D. Gossen ◽  
Mary Ruth McDonald
Keyword(s):  
Brassica Napus ◽  
Microscopic Observation ◽  
Seed Treatment ◽  
Plasmodiophora Brassicae ◽  
Piriformospora Indica ◽  
Brassica Crops ◽  
Growth Room ◽  
Treated Seed ◽  
Important Disease

A Basidiomycete endomycorrhizal fungus, Piriformospora indica, colonizes and promotes the growth of canola and other Brassica crops, and can reduce diseases of other crops. Clubroot is an important disease of Bbrassica crops caused by the obligate, soil-borne pathogen Plasmodiophora brassicae. The effect of P. indica on clubroot severity in canola was assessed in replicated growth room studies. Seed was treated with P. indica using a proprietary process. Microscopic observation confirmed that canola roots grown from treated seed were colonized by P. indica. However, P. indica did not consistently reduce clubroot severity and did not promote the growth of canola.

Putative role of IAA during the early response of Brassica napus L. to Plasmodiophora brassicae

2016 ◽  
Vol 145 (3) ◽  
pp. 601-613 ◽  
Author(s):  
Li Xu ◽  
Li Ren ◽  
Kunrong Chen ◽  
Fan Liu ◽  
Xiaoping Fang
Keyword(s):  
Brassica Napus ◽  
Plasmodiophora Brassicae ◽  
Early Response ◽  
Brassica Napus L ◽  
Putative Role

scholarly journals Comparative Transcriptome Analysis of Rutabaga (Brassica napus) Cultivars Indicates Activation of Salicylic Acid and Ethylene-Mediated Defenses in Response to Plasmodiophora brassicae

2020 ◽  
Vol 21 (21) ◽  
pp. 8381
Author(s):  
Qinqin Zhou ◽  
Leonardo Galindo-González ◽  
Victor Manolii ◽  
Sheau-Fang Hwang ◽  
Stephen E. Strelkov
Keyword(s):  
Salicylic Acid ◽  
Brassica Napus ◽  
Defense Mechanisms ◽  
Plasmodiophora Brassicae ◽  
Leucine Zippers ◽  
Brassica Napus L ◽  
Soilborne Disease ◽  
Essential Components ◽  
Genes Encoding ◽  
Respiratory Burst Oxidase

Clubroot, caused by Plasmodiophora brassicae Woronin, is an important soilborne disease of Brassica napus L. and other crucifers. To improve understanding of the mechanisms of resistance and pathogenesis in the clubroot pathosystem, the rutabaga (B. napus subsp. rapifera Metzg) cultivars ‘Wilhelmsburger’ (resistant) and ‘Laurentian’ (susceptible) were inoculated with P. brassicae pathotype 3A and their transcriptomes were analyzed at 7, 14, and 21 days after inoculation (dai) by RNA sequencing (RNA-seq). Thousands of transcripts with significant changes in expression were identified in each host at each time-point in inoculated vs. non-inoculated plants. Molecular responses at 7 and 14 dai supported clear differences in the clubroot response mechanisms of the two genotypes. Both the resistant and the susceptible cultivars activated receptor-like protein (RLP) genes, resistance (R) genes, and genes involved in salicylic acid (SA) signaling as clubroot defense mechanisms. In addition, genes related to calcium signaling and genes encoding leucine-rich repeat (LRR) receptor kinases, the respiratory burst oxidase homolog (RBOH) protein, and transcription factors such as WRKYs, ethylene responsive factors, and basic leucine zippers (bZIPs), appeared to be upregulated in ‘Wilhelmsburger’ to restrict P. brassicae development. Some of these genes are essential components of molecular defenses, including ethylene (ET) signaling and the oxidative burst. Our study highlights the importance of activation of genes associated with SA- and ET-mediated responses in the resistant cultivar. A set of candidate genes showing contrasting patterns of expression between the resistant and susceptible cultivars was identified and includes potential targets for further study and validation through approaches such as gene editing.

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