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.

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.

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.

Influence of resistant cultivars and crop intervals on clubroot of canola

2019 ◽  
Vol 99 (6) ◽  
pp. 862-872 ◽  
Author(s):  
S.F. Hwang ◽  
H.U. Ahmed ◽  
Q. Zhou ◽  
H. Fu ◽  
G.D. Turnbull ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Seed Yield ◽  
Plant Biomass ◽  
Plasmodiophora Brassicae ◽  
Disease Index ◽  
Yield Increase ◽  
Resting Spore ◽  
Important Constraint ◽  
Significant Yield ◽  
Very High

Clubroot, caused by Plasmodiophora brassicae, is an important constraint on canola (Brassica napus) production in Canada. Rotations of clubroot-resistant (CR) canola cultivars in various sequences and planting intervals between canola with non-host crops and fallow periods were evaluated to determine their effects on clubroot severity and P. brassicae resting spore populations under field and micro-plot conditions. Under micro-plot conditions, the rotation sequences including CR canola, continuous fallow, and the non-host barley reduced gall weight by 63%–100% and clubroot severity by 34%–100% compared with continuous planting of susceptible canola. No visible clubroot symptoms developed following continuous fallow or the non-host crop. Under field conditions, clubroot severity was very high (78% disease index) in the continuous susceptible canola sequence. Most of the CR canola rotation sequences significantly reduced clubroot severity by 12%–23%, but continuous fallow, continuous barley, and alternating the CR canola cultivars ‘45H29’ or ‘73-47’ with ‘TC72429-10’ reduced clubroot severity by 32%–36%. A comparison of intervals between canola crops and four cropping sequences (continuous susceptible canola, alternating canola with barley or pea, a 2-yr non-host interval between canola crops, and a 3-yr non-host interval between canola crops) was conducted over 5 yr. A 2- or 3-yr non-host interval improved plant height, plant biomass, and seed yield, and reduced gall mass, P. brassicae propagules in the soil, and clubroot severity. A significant yield increase of more than 3600% was observed in a 3-yr non-host interval.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil

2019 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Qixing Zhou ◽  
David Feindel ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

AbstractClubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot has been challenging, due largely to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores g-1 soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C and being buried in the soil were better conditions for spore survival than were −20°C, 30°C and at the soil surface. Most of the spores kept on the soil surface were killed, suggesting the negative effect of light on spore viability. Additional experiments confirmed that ultraviolet (UV) light contributed a large negative effect on spore viability as lower pathogenicity and less DNA content were observed from the 2-and 3-hour UV light treated spores compared to the untreated control. Finally, this work demonstrated that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil.

2021 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Hafiz Ahmed ◽  
Qixing Zhou ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

Clubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot is challenging, largely due to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores/g soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C, and being buried in the soil were more conductive conditions for spore survival compared to -20°C, 30°C, and at the soil surface. 99.99% of the spores kept on the soil surface were non-viable, suggesting a negative effect of light on spore viability. Additional experiments confirmed the negative effect of UV light on spore viability as spores receiving 2- and 3-hour UV light exhibited lower disease potential and contained less DNA content compared to the untreated control. Finally, this work confirmed that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

Effect of canola (Brassica napus) cultivar rotation on Plasmodiophora brassicae pathotype composition

2020 ◽  
Vol 100 (2) ◽  
pp. 218-225 ◽  
Author(s):  
Tiesen Cao ◽  
Victor P. Manolii ◽  
Qixing Zhou ◽  
Sheau-Fang Hwang ◽  
Stephen E. Strelkov
Keyword(s):  
Brassica Napus ◽  
Quantitative Pcr ◽  
Plasmodiophora Brassicae ◽  
Pcr Analysis ◽  
Susceptible Cultivar ◽  
Specific Primers ◽  
Greenhouse Experiments ◽  
Pathogen Populations ◽  
Soil Mix ◽  
The Impact

In Canada, clubroot (Plasmodiophora brassicae) disease is managed mainly by planting clubroot resistant (CR) canola (Brassica napus). New pathotypes of P. brassicae have emerged recently, however, which are virulent on most CR canola cultivars. To understand the impact of cultivar rotation on pathotype abundance, greenhouse experiments were conducted in which different canola cultivar rotations were grown in a soil mix containing equal amounts of pathotypes 5X and 3, which are virulent and avirulent, respectively, on CR canola. The rotation treatments included: T1, the same susceptible cultivar planted over four cycles; T2, the same CR cultivar planted over four cycles; and T3, different CR cultivars planted in each cycle. Clubroot severity increased from cycles one to four in all treatments, with the exception of one CR cultivar in T3 that may carry a different source of resistance. Pathogen populations were recovered with a susceptible bait crop and pathotyped on the differentials of Williams plus a CR host (B. napus ‘Mendel’). The percentage of galls classified as pathotype 5X in T1 declined from 50% to 6.7% over the course of the experiment, while galls classified as pathotype 5X increased from 50% to 66.7% in both T2 and T3. Quantitative PCR analysis of the soil with pathotype 5X-specific primers generally confirmed an increase in 5X DNA. The results suggest that continuous planting of CR canola favours a rapid proliferation of virulent pathotypes of P. brassicae, as indicated by the increases in pathotype 5X observed in this study.

scholarly journals Identification of Plasmodiophora brassicae Wor. isolate suppressing clubroot resistance in ‘Kilaxy’ F1 white cabbage

2014 ◽  
Vol 26 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Maria Wesołowska
Keyword(s):  
Plant Resistance ◽  
Plasmodiophora Brassicae ◽  
The Other ◽  
Infestation Level ◽  
Harvest Time ◽  
Clubroot Resistance ◽  
Resting Spore ◽  
Resistant Genes ◽  
Seed Inoculation ◽  
White Cabbage

ABSTRACT The purpose of this study was the evaluation of the pathogenicity of Plasmodiophora brassicae Wor. field isolates gathered from clubroot-infected white cabbage Brassica oleracea var. capitata L. f. alba plants grown in different areas of Poland. The virulence of seven isolates of the pathogen was tested. Breeding materials from white cabbage resistant and susceptible to P. brassicae were used as standard objects for isolate virulence screening. Cabbage seeds were infected by submerging them into a resting-spore suspension. A screening of plant resistance using a nine-degree scale based on root symptoms was carried out at the eight-week-old plantlets stage and at harvest time on afield infected by P. brassicae spores. Isolates from Pobiednik and Grębałów were defined as more virulent. The P isolate from Pobiednik also infested plants of the clubroot resistant ‘Kilaxy’ F1 cultivar, which indicated the suppression of clubroot resistance. Its reaction to the other six isolates confirmed the resistance of this cultivar. The susceptible HTM line was characterised by the highest infestation level. A difference in the susceptibility level was noticed between lines derived from those with resistant genes, i.e. Oregon123 and ‘Badger Shipper’. The Oregon123 line was less susceptible to the applied isolates. The effect of the isolates used for seed inoculation on the reaction of the dormant plants to the pathogen on the clubroot field was observed.

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