Histopathology of the Plasmodiophora brassicae-Chinese Cabbage Interaction in Hosts Carrying Different Sources of Resistance

Clubroot is a serious soil-borne disease of crucifers caused by the obligate parasite Plasmodiophora brassicae. The genetic basis and histopathology of clubroot resistance in two Chinese cabbage (Brassica rapa ssp. pekinensis) inbred lines Bap055 and Bap246, challenged with pathotype 4 of P. brassicae, was evaluated. The Chinese cabbage cultivar “Juxin” served as a susceptible check. The resistance in Bap055 was found to be controlled by the CRa gene, while resistance in Bap246 fit a model of control by unknown recessive gene. Infection of the roots by P. brassicae was examined by inverted microscopy. Despite their resistance, primary and secondary infection were observed to occur in Bap055 and Bap246. Primary infection was detected at 2 days post-inoculation (DPI) in “Juxin,” at 4 DPI in Bap055, and at 6 DPI in Bap246. Infection occurred most quickly on “Juxin,” with 60% of the root hairs infected at 10 DPI, followed by Bap055 (31% of the root hairs infected at 12 DPI) and Bap246 (20% of the root hairs infected at 14 DPI). Secondary infection of “Juxin” was first observed at 8 DPI, while in Bap055 and Bap246, secondary infection was first observed at 10 DPI. At 14 DPI, the percentage of cortical infection in “Juxin,” Bap055 and Bap246 was 93.3, 20.0, and 11.1%, respectively. Although cortical infection was more widespread in Bap055 than in Bap246, secondary infection in both of these hosts was restricted relative to the susceptible check, and the vascular system remained intact. A large number of binucleate secondary plasmodia were observed in “Juxin” and the vascular system was disrupted at 16 DPI; in Bap055 and Bap246, only a few secondary plasmodia were visible, with no binucleate secondary plasmodia. The defense mechanisms and expression of resistance appears to differ between Chinese cabbage cultivars carrying different sources of resistance.

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The Role of Primary and Secondary Infection in Host Response to Plasmodiophora brassicae

Phytopathology ◽

10.1094/phyto-07-13-0189-r ◽

2014 ◽

Vol 104 (10) ◽

pp. 1078-1087 ◽

Cited By ~ 22

Author(s):

Mary Ruth McDonald ◽

Kalpana Sharma ◽

Bruce D. Gossen ◽

Abhinandan Deora ◽

Jie Feng ◽

...

Keyword(s):

Plasmodiophora Brassicae ◽

Secondary Infection ◽

Root Hairs ◽

Secondary Phase ◽

Primary Phase ◽

Root Cortex ◽

Resting Spores ◽

Cortical Infection ◽

Root Hair Infection

The disease cycle of Plasmodiophora brassicae consists of a primary phase in root hairs followed by a secondary phase in the root cortex and adjacent tissues. However, the role of root hair infection in subsequent cortical infection and development of P. brassicae is not well understood. To examine the role of the primary and secondary stages separately, inoculation studies with resting spores (source of primary zoospores) and secondary zoospores of a virulent and avirulent pathotype were conducted on canola (Brassica napus). The size of secondary zoospores and number of nuclei were also examined. The zoospores were larger (≈9.6 to 14.4 μm) than in previous reports and all were uninucleate. Inoculation with secondary zoospores alone produced both primary and secondary infection, even with the avirulent pathotype. No symptoms developed from inoculation with avirulent primary zoospores but tiny, bead-shaped clubs developed from inoculation with avirulent secondary zoospores. Inoculation with virulent secondary zoospores alone resulted in lower disease severity than inoculation with virulent resting spores alone. The results indicate that recognition of infection by the host and initiation of a response (induction or suppression of resistance) occurs during primary infection, although recognition can also occur during cortical infection and development.

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Transcriptome and Coexpression Network Analyses Reveal Hub Genes in Chinese Cabbage (Brassica rapa L. ssp. pekinensis) During Different Stages of Plasmodiophora brassicae Infection

Frontiers in Plant Science ◽

10.3389/fpls.2021.650252 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yuxiang Yuan ◽

Liuyue Qin ◽

Henan Su ◽

Shuangjuan Yang ◽

Xiaochun Wei ◽

...

Keyword(s):

Chinese Cabbage ◽

Plasmodiophora Brassicae ◽

Primary Root ◽

Resistance Mechanisms ◽

Coexpression Network ◽

Hub Genes ◽

Clubroot Resistance ◽

Network Analyses ◽

Cortical Infection ◽

Root Hair Infection

Clubroot, caused by the soil-borne protist Plasmodiophora brassicae, is one of the most destructive diseases of Chinese cabbage worldwide. However, the clubroot resistance mechanisms remain unclear. In this study, in both clubroot-resistant (DH40R) and clubroot-susceptible (DH199S) Chinese cabbage lines, the primary (root hair infection) and secondary (cortical infection) infection stages started 2 and 5 days after inoculation (dai), respectively. With the extension of the infection time, cortical infection was blocked and complete P. brassica resistance was observed in DH40R, while disease scales of 1, 2, and 3 were observed at 8, 13, and 22 dai in DH199S. Transcriptome analysis at 0, 2, 5, 8, 13, and 22 dai identified 5,750 relative DEGs (rDEGs) between DH40R and DH199S. The results indicated that genes associated with auxin, PR, disease resistance proteins, oxidative stress, and WRKY and MYB transcription factors were involved in clubroot resistance regulation. In addition, weighted gene coexpression network analysis (WGCNA) identified three of the modules whose functions were highly associated with clubroot-resistant, including ten hub genes related to clubroot resistance (ARF2, EDR1, LOX4, NHL3, NHL13, NAC29, two AOP1, EARLI 1, and POD56). These results provide valuable information for better understanding the molecular regulatory mechanism of Chinese cabbage clubroot resistance.

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New Sources of Resistance to Black rot in Crucifers and Inheritance of Resistance.

HortScience ◽

10.21273/hortsci.25.9.1122f ◽

1990 ◽

Vol 25 (9) ◽

pp. 1122f-1122

Author(s):

Z. H. Guo ◽

M. H. Dickson ◽

J. E. Hunter

Keyword(s):

Chinese Cabbage ◽

Dominant Gene ◽

Recessive Gene ◽

Brassica Species ◽

Black Rot ◽

Inheritance Of Resistance ◽

Quantitative Inheritance ◽

Sources Of Resistance ◽

Moderate Resistance ◽

High Level

Resistance to Black rot was studied in B. oleracea, B. campestris and B. napus, using three different inoculation procedures. The results indicated that hydathode inoculation without wounding and the wound suspension technique were useful for differentiating levels of resistance found in B. oleracea and B. campestris, but not in B. napus. Only the wound colony method allowed differentiation between high and moderate resistance in B napus. B. napus, PI 199947 and PI 199949, exhibited the highest resistance found in cultivated Brassica species. In B. campestris, two chinese cabbage accessions showed quantitative inheritance for moderate levels of resistance. In B. napus, the high level of reistance was conferred by one dominant gene, to which the symbol Br was assigned, whereas the moderate resistance was due to one recessive gene bm.

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Infection and Gene Expression of the Clubroot Pathogen Plasmodiophora brassicae in Resistant and Susceptible Canola Cultivars

Plant Disease ◽

10.1094/pdis-11-15-1255-re ◽

2016 ◽

Vol 100 (4) ◽

pp. 824-828 ◽

Cited By ~ 6

Author(s):

Weixin Fei ◽

Jie Feng ◽

Songbai Rong ◽

Stephen E. Strelkov ◽

Zhimou Gao ◽

...

Keyword(s):

Primary Infection ◽

Plasmodiophora Brassicae ◽

Secondary Infection ◽

Quantitative Polymerase Chain Reaction ◽

Expression Patterns ◽

Root Hairs ◽

Resistant Cultivar ◽

In Planta ◽

Secondary Infections ◽

Polymerase Chain

Infection by the clubroot pathogen Plasmodiophora brassicae on resistant and susceptible canola cultivars was investigated at various times following inoculation. Primary infection occurred on more than 90% of root hairs in both cultivars at 7 days after inoculation (dai), and thereafter declined to less than 20% at 14 to 35 dai. The amount of primary infection on the two cultivars was similar at each time point. Secondary infections were rare in both cultivars at 5 and 7 dai but became common after 14 dai. At 14 to 28 dai, the level of secondary infection was greater in the resistant cultivar than in the susceptible one. The in planta expression of 12 selected P. brassicae genes was investigated by reverse-transcription quantitative polymerase chain reaction. All genes were upregulated at 5 or 7 dai in the resistant cultivar. In the susceptible cultivar, the 12 genes could be classified into three groups according to their expression patterns: 2 genes showed an expression peak at 14 dai, 3 showed two expression peaks at 14 and 35 dai, and the others showed an expression peak at 35 dai. Results from this study will be useful in breeding for resistance and in selecting candidate pathogenicity genes for further studies.

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Plasmodiophora brassicae in Yunnan and its Resistant Sources in Chinese Cabbage

International Journal of Agriculture and Biology ◽

10.17957/ijab/15.1732 ◽

2021 ◽

Vol 25 (04) ◽

pp. 805-812

Author(s):

Xueyu Han

Keyword(s):

Differential System ◽

Resistance Genes ◽

Chinese Cabbage ◽

Yunnan Province ◽

Plasmodiophora Brassicae ◽

Sources Of Resistance ◽

Clubroot Disease ◽

Resistant Genes ◽

Disease Resistant ◽

Resistant Sources

The Williams differential system was employed for pathotype identification of 34 Plasmodiophora brassicaeroot samples collected from Yunnan Province and pathotypes 1, 2, 4, 10 and 14 were detected. Pathotype 4 was dominant with 70.59% of all the samples in Yunnan. The distribution of the P. brassicae pathotypes was mapped. Resistance to P. brassicae (clubroot disease) was investigated in 22 Chinese cabbage cultivars and it was found that the cultivar Shangpin had multiple resistances and was immune while Shangpin CR527 and Shangpin CR523 were resistant to P. brassicae. These cultivars can be used by farmers as sources of resistance to P. brassicae, to aid them in reducing disease in their crops. Seven known clubroot-resistant genes were detected in the 22 Chinese cabbage cultivars. CRa and CRb were found to be the most resistant to P. brassicae pathotype 4. Beisheng CR12 was resistant to pathotypes 1, 4, 10 and 14, but did not carry any known resistance genes, which indicated that unknown resistant genes were present. This study will lay the foundation for the control of clubroot disease and promote disease-resistant breeding of Chinese cabbage. © 2021 Friends Science Publishers

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Identification of physiological races of Plasmodiophora brassicae causing club root in Chinese cabbage from Northeast China

JOURNAL OF HUNAN AGRICULTURAL UNIVERSITY ◽

10.3724/sp.j.1238.2013.00176 ◽

2014 ◽

Vol 39 (2) ◽

pp. 176-178 ◽

Cited By ~ 2

Author(s):

Yang ZHAO ◽

Yuan-jun BAI ◽

Ze-yan MIAO ◽

Ying LI ◽

Kui-hua ZHAO

Keyword(s):

Chinese Cabbage ◽

Northeast China ◽

Plasmodiophora Brassicae ◽

Physiological Races

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Quantitative Resistance to witches’ broom disease in progenies of different sources of resistance.

Crop Protection ◽

10.1016/j.cropro.2021.105678 ◽

2021 ◽

pp. 105678

Author(s):

Alezania Silva Pereira ◽

Uilson Vanderlei Lopes ◽

José Luís Pires ◽

Mariana Araujo Barreto ◽

Lindolfo Pereira dos Santos ◽

...

Keyword(s):

Quantitative Resistance ◽

Sources Of Resistance ◽

Broom Disease ◽

Different Sources

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The life history of Plasmodiophora brassicae Woron

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1972.0008 ◽

1972 ◽

Vol 180 (1058) ◽

pp. 103-112 ◽

Cited By ~ 109

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.

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

Plant Disease ◽

10.1094/pdis-02-21-0410-re ◽

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.

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