scholarly journals Temporal dynamics of bacterial and fungal communities during the infection of Brassica rapa roots by the protist Plasmodiophora brassicae: The impact of a pathogen on the plant root and rhizosphere microbiota

2018 ◽  
Author(s):  
Lionel Lebreton ◽  
Anne-Yvonne Guillerm-Erckelboudt ◽  
Kévin Gazengel ◽  
Juliette Linglin ◽  
Morgane Ourry ◽  
...  

AbstractThe temporal dynamics of rhizosphere and root microbiota composition was compared between healthy and infected Chinese cabbage plants by the pathogen Plasmodiophora brassicae. When inoculated with P. brassicae, disease was measured at five sampling dates from early root hair infection to late gall development. The first symptoms of clubroot disease appeared 14 days after inoculation (DAI) and increased drastically between 14 and 35 DAI. The structure of microbial communities associated to rhizosphere soil and root from healthy and inoculated plants was characterized through high-throughput DNA sequencing of bacterial (16S) and fungal (18S) molecular markers and compared at each sampling date. In healthy plants, Proteobacteria and Bacteroidetes bacterial phyla dominated the rhizosphere and root microbiota of Chinese cabbage. Rhizosphere bacterial communities contained higher abundances of Actinobacteria and Firmicutes compared to the roots. Moreover, a drastic shift of fungal communities of healthy plants occurred between the two last sampling dates, especially in plant roots, where most of Ascomycota fungi dominated until they were replaced by a fungus assigned to the Chytridiomycota phylum. Parasitic invasion by P. brassicae disrupted the rhizosphere and root-associated community assembly at a late step during the root secondary cortical infection stage of clubroot disease. At this stage, Flavisolibacter and Streptomyces in the rhizosphere, and Bacillus in the roots, were drastically less abundant upon parasite invasion. Rhizosphere of plants colonized by P. brassicae was significantly more invaded by the Chytridiomycota fungus, which could reflect a mutualistic relationship in this compartment between these two microorganisms.

2018 ◽  
pp. 97-100
Author(s):  
A. A. Ushakov ◽  
L. L. Bondareva ◽  
I. A. Engalycheva

Clubroot disease (causative organism Plasmodiophora brassicae Wor.) is among the most economically important and harmful diseases of the cole crops, and the damage due to this disease may reach up to 50-75% of the yield and even 100% in epiphytotics years. Even resistant varieties become susceptible over the years, because of appearance of the new pathogen races and change of climatic conditions in the main growing areas of the crop. In this context the Laboratory of Plant Immunity and Protection, of Federal State Budgetary Scientific Institution “Federal Scientific Vegetable Center” implements continuous phytoimmunological evaluation of collection and selection specimens and also directional material rather than just annual monitoring of causative organism dissemination in order to find new resistance sources. For this purpose an artificial infection background is used: compost obtained from decomposed nodules on the cabbage roots affected by clubroot disease (infection load 105-106 spores/cm3). The resistance of white cabbage varieties was evaluated during the harvesting period using five-point score of the root system damage, which formed the basis for categorization into resistance groups. For the analysis of artificial background intensity and specimen ranking the individual plants of the white cabbage variety Slava 1305, which is a susceptibility standard, were randomly planted in the entire area of the infection background. The impact of atmospheric conditions in the study year on the results of phytopathological evaluation of cabbage selection specimens against the infection background is demonstrated. Under unfavorable conditions for pathogen development (2014) the most specimens (74%) were categorized as relatively resistant, while in favourable for pathogen year 2015 relatively resistant specimens comprised only 5% of the total number of studied specimens. Since the same specimen may show different level of resistance depending on the year conditions, the stability of character manifestation is the important criterion for identification of the resistance resources. Phytopathological evaluation aimed on selection of clubroot-resistant forms in the Moscow region should last for at least three years even with the use of infection background. Long-lasting evaluation showed that the strains No 234/15,140/14,216/17 exhibiting high resistance to clubroot against artificial infection background regardless of the year conditions are the most valuable for selection. The resistance of white cabbage selection varieties to clubroot disease was studied against the infection background.


PLoS ONE ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. e0204195 ◽  
Author(s):  
Lionel Lebreton ◽  
Anne-Yvonne Guillerm-Erckelboudt ◽  
Kévin Gazengel ◽  
Juliette Linglin ◽  
Morgane Ourry ◽  
...  

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S87-S94 ◽  
Author(s):  
G.R. Dixon

Host plants and soil borne pathogens that attack them exist within an ecological matrix populated by numerous microbial species that may influence the access of pathogenesis. These events are moderated by physical and chemical components of the soil. The impact of inorganic and organic nutrients on pathogenesis and the development of host resistance are discussed in this review using two host – pathogen combinations as examples. Calcium, boron, nitrogen and pH have been demonstrated to affect the processes of resting spore germination, host invasion and colonisation in the Plasmodiophora brassicae-Brassica combination that results in clubroot disease. Organic nutrients that have associated biostimulant properties have been demonstrated to influence the development of Pythium ultimum-Brassica combination that results in damping-off disease. This latter combination is affected by the presence of antagonistic microbial flora as demonstrated by increased ATP, extra-cellular enzyme and siderophore production. In both examples there are indications of the manner by which host resistance to pathogenesis may be enhanced by changes to the nutrient status surrounding host plants. These effects are discussed in relation to the development of integrated control strategies that permit disease control with minimal environmental impact.


Plant Disease ◽  
2015 ◽  
Vol 99 (6) ◽  
pp. 776-779 ◽  
Author(s):  
Hui Zhang ◽  
Jie Feng ◽  
Shujiang Zhang ◽  
Shifan Zhang ◽  
Fei Li ◽  
...  

Clubroot disease, caused by Plasmodiophora brassicae Woronin, has become a major problem in cruciferous crops worldwide. Chinese cabbage (Brassica rapa), pak choi (B. rapa), and mustard (B. juncea) are important vegetable crops in China. Development of clubroot-resistant cultivars of these crops is urgently needed. In this study, 71 B. rapa and B. juncea genotypes from China, including cultivars and inbred lines, were evaluated for resistance to three P. brassicae pathotypes. A significant interaction was observed between the P. brassicae pathotypes and the Brassica genotypes. Pathotype 3, as defined on the differentials of Williams, exhibited the weakest virulence on all plant material. By contrast, pathotypes 5 and 6 were both highly pathogenic on most of the tested genotypes. In all, 10 of the 14 Chinese cabbage cultivars were resistant to all three pathotypes, while 4 were resistant only to a specific pathotype. Seven of eight progenies obtained from the selfing of Chinese cabbage cultivars were resistant to pathotype 3 but most were susceptible to pathotypes 5 and 6. Most inbred lines of Chinese cabbage and all inbred lines of pak choi and mustard were susceptible to all three pathotypes but their susceptibility was lower to pathotype 3 than to pathotypes 5 and 6.


2021 ◽  
Vol 12 ◽  
Author(s):  
Yuanliang Hu ◽  
Lu Qiu ◽  
Zongjie Zhang ◽  
Kai Liu ◽  
Xian Xia ◽  
...  

Clubroot caused by Plasmodiophora brassicae is one of the most destructive diseases in cruciferous crops. Streptomyces alfalfae XY25T, a biological control agent, exhibited great ability to relieve clubroot disease, regulate rhizosphere bacterial and fungal communities in Chinese cabbage, and promote its growth in greenhouse. Therefore, field experiments were carried out to investigate the effects of S. alfalfae XY25T on clubroot and rhizosphere microbial community in Chinese cabbage. Results showed that the control efficiency of clubroot by S. alfalfae XY25T was 69.4%. Applying the agent can alleviate soil acidification; increase the contents of soil organic matter, available nitrogen, available phosphorus, and available potassium; and enhance activities of invertase, urease, catalase, and alkaline phosphatase. During Chinese cabbage growth, bacterial diversity decreased first and then increased, and fungal diversity decreased gradually after inoculation with S. alfalfae XY25T. High-throughput sequencing analysis showed that the main bacterial phyla were Proteobacteria, Bacteroidetes, Acidobacteria, and Planctomycetes, and the major fungal phyla were Ascomycota and Basidiomycota in rhizosphere soil. The dominant bacterial genera were Flavobacterium, Candidatus, Pseudomonas, Stenotrophomonas, Sphingomonas, Flavisolibacter, and Gemmatimonbacteria with no significant difference in abundance, and the major fungal genera were Monographella, Aspergillus, Hypocreales, Chytridiaceae, Fusarium, Pleosporales, Agaricales, Mortierella, and Pleosporales. The significant differences were observed among Pleosporales, Basidiomycota, Colletotrichum, two strains attributed to Agaricales, and another two unidentified fungi by using S. alfalfae XY25T. Moreover, quantitative real-time PCR results indicated that P. brassicae content was significantly decreased after the agent inoculation. In conclusion, S. alfalfae XY25T can affect rhizosphere microbial communities; therefore, applying the agent is an effective approach to reduce the damage caused by clubroot.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Yu Gao ◽  
Guanghui Xu

Clubroot disease, caused byPlasmodiophora brassicae, is a serious soil-borne disease of crucifer worldwide, and it can significantly reduce yield and quality. Although some agrochemicals have been used to manage clubroot and can provide effective control, increasing use of chemical inputs causes several negative effects. In this study, using Chinese cabbage (Brassica rapaL. subsp.chinensis) as the test crop, we developed an effective nonchemical method that would protect the roots againstP. brassicaeinfection by using a combination heat treatment and a cocktail of biocontrol agents. The data showed that this method could cause 91.7% inhibition ofP. brassicaeinfection. The average height of plants (13.5 cm) using this method was about twice higher than that in control group (6.7 cm), and the average plant weight (3.19 g) was about three times increased compared to that in control set (1.23 g).


2020 ◽  
Vol 21 (11) ◽  
pp. 3896 ◽  
Author(s):  
Rawnak Laila ◽  
Arif Hasan Khan Robin ◽  
Jong-In Park ◽  
Gopal Saha ◽  
Hoy-Taek Kim ◽  
...  

The obligate biotroph Plasmodiophora brassicae causes clubroot disease in oilseeds and vegetables of the Brassicaceae family, and cytokinins play a vital role in clubroot formation. In this study, we examined the expression patterns of 17 cytokinin-related genes involved in the biosynthesis, signaling, and degradation in Chinese cabbage inoculated with the Korean pathotype group 4 isolate of P. brassicae, Seosan. This isolate produced the most severe clubroot symptoms in Chinese cabbage cultivar “Bullam-3-ho” compared to three other Korean geographical isolates investigated. BrIPT1, a cytokinin biosynthesis gene, was induced on Day 1 and Day 28 in infected root tissues and the upregulation of this biosynthetic gene coincided with the higher expression of the response regulators BrRR1, on both Days and BrRR6 on Day 1 and 3. BrRR3 and 4 genes were also induced during gall enlargement on Day 35 in leaf tissues. The BrRR4 gene, which positively interact with phytochrome B, was consistently induced in leaf tissues on Day 1, 3, and 14 in the inoculated plants. The cytokinin degrading gene BrCKX3-6 were induced on Day 14, before gall initiation. BrCKX2,3,6 were induced until Day 28 and their expression was downregulated on Day 35. This insight improves our current understanding of the role of cytokinin signaling genes in clubroot disease development.


2021 ◽  
Author(s):  
Sebastian Martinez

Rice is an important crop in Uruguay associated mostly with livestock production in a rice and pasture rotation system since the 1920s. However, in recent years there has been interest in intensifying the production in some of these systems to satisfy market demands and increase income. Intensification occurs by augmenting the rice frequency in the rotation, including new crops like sorghum and soybean, or shortening the pasture phase. A long-term experiment was established in 2012 in the main rice producing area of Uruguay with the objective to study the impact of intensification in rice rotations. After the first cycle of rotation soils from seven rotation phases were sampled and microbial communities were studied by means of high-throughput sequencing of Illumina NovaSeq 6000. Archaeal/bacterial and fungal community composition were studied (16S rRNA and 18S gene regions) detecting 3662 and 807 bacterial and fungal Operational Taxonomic Units (OTUs), respectively. Actinobacteria, Firmicutes and Proteobacteria were the most common bacterial phyla. Among them, only Proteobacteria differed significantly between rotations. Although most fungal OTUs were unidentified, Ascomycota, Basidiomycota and Mucoromycota were the most abundant fungal classes within identified taxa. Bacterial communities differed between rotations forming three groups according to the percentage of rice in the system. Fungal communities clustered in four groups, although not well differentiated, and mostly associated with the antecessor crop. Only P and C:N varied between rotations among soil physicochemical variables after six years, and individual bacterial OTUs appeared weakly influenced by P, pH, Mg and fungal OTUs by P. The results suggest that after six years, bacteria/archaeal communities were influenced by the time with rice in the rotation, and fungal communities were more influenced by the antecessor crop. More studies are needed to associate fungal communities with certain rotational or environmental variables. Some taxa were associated with a particular rotation, and some bacterial taxa were identified as biomarkers. Fungal indicator taxa were not identified at the species level for any rotation.


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