Influence of soil type and pH on the colonisation of sugar beet seedlings by antagonistic Pseudomonas and Bacillus strains, and on their control of Pythium damping-off

Schmidt, Christoph Stephan; Agostini, Francesco; Simon, Ana-maria; Whyte, Jennifer; Townend, John; Leifert, Carlo; Killham, Ken; Mullins, Chris

doi:10.1007/s10658-004-1600-y

Cited by 29 publications

(10 citation statements)

References 64 publications

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“…The in vivo assay confirmed that the antagonists are harmless to the plants and that they are more effective in combination than when acting individually in reducing root rot caused by P. capsici (reduction up to 75%). This result supports the use of a combination of compatible antagonists selected for their different biological properties (including antibiosis, microparasitism, enzymatic lysis and, probably, the ability to compete for space and nutrients), lending weight to the suggestion of other authors (Guetsky et al., 2001; Schmidt et al., 2004; Li et al., 2005) that the use of more than one biocontrol agent is necessary for reducing the vagaries of biological control. Using the characteristics of a combination of antagonists, as developed in this study, opens up the possibility of designing future strategies for transferring the knowledge gained to the control of other pathogens.…”

Section: Discussionsupporting

confidence: 80%

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Ezziyyani

Requena

Egea‐Gilabert

et al. 2007

Journal of Phytopathology

117

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A combination of two compatible micro-organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper. The population of the pathogen in soil was reduced by 75% as a result. Vegetative growth of the mycelium of P. capsici was inhibited in vitro on the second day after P. capsici and T. harzianum were placed on the opposite sides of the same Petri plate. Trichoderma harzianum was capable of not only arresting the spread of the pathogen from a distance, but also after invading the whole surface of the pathogen colony, sporulating over it. Scanning electron microscopy showed the hyphae of P. capsici surrounded by those of T. harzianum, their subsequent disintegration, and the eventual suppression of the pathogen's growth. Streptomyces rochei produced a zone of inhibition, from which was obtained a compound with antioomycete property secreted by the bacteria. When purified by high-pressure liquid chromatography, this compound was identified as 1-propanone, 1-(4-chlorophenyl), which seems to be one of the principal compounds involved in the antagonism. A formulation was prepared that maintained the compound's capacity to inhibit growth of the pathogen for up to 2 years when stored at room temperature in the laboratory on a mixture of plantation soil and vermiculite. The two antagonists, added as a compound formulation, were effective at pH from 3.5 to 5.6 at 23-30°C. The optimal dose of the antagonists in the compound formulation was 3.5 · 10 8 spores/ml of T. harzianum and 1.0 · 10 9 FCU/ml of S. rochei. This is the first report of a compound biocontrol formulation of these two antagonists with a potential to control root rot caused by P. capsici.

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Section: Discussionsupporting

confidence: 80%

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Ezziyyani

Requena

Egea‐Gilabert

et al. 2007

Journal of Phytopathology

117

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“…Bacillus subtilis 101 inoculum consisted of equal amounts of vegetative cells and endospores in order to provide a sufficient and constant number of cells in an active physiological state, and to prevent differences in root colonization behaviour as reported by Schmidt et al (2004). Trends of population dynamic of B. subtilis 101 on tomato rhizosphere suggest that a consistent turnover from vegetative cells to spores and from spores to vegetative cells may occur in peat but not in sandy‐loam soil.…”

Section: Discussionmentioning

confidence: 96%

Development of a strain-specific genomic marker for monitoring a Bacillus subtilis biocontrol strain in the rhizosphere of tomato

Felici

Vettori

Toffanin

et al. 2008

FEMS Microbiology Ecology

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A strain-specific molecular marker enabling the detection and tracking of the biological control agent Bacillus subtilis 101, when released into the environment, was developed. Random amplified polymorphic DNA (RAPD) technique was used to differentiate this from other B. subtilis strains. A differentially amplified fragment obtained from RAPD profiles was sequenced and characterized as sequence-characterized amplified region (SCAR) marker, and four primer pairs were designed and evaluated for their specificity towards this strain. The sensibility of the selected SCAR primer pair was evaluated by qualitative PCR and Southern blotting, and the detection limit was assessed around 10(2) CFU (g dry wt soil)(-1), thus providing a reliable tool for the traceability of this B. subtilis strain in greenhouse or field trials. A plating assay coupled to PCR with the SCAR primer pair was then used as a detection method in microcosm experiments for monitoring the population of B. subtilis 101 in the rhizosphere of tomato, grown under two different soil conditions, i.e. nonsterile peat-based substrate and sandy-loam agricultural soil, respectively. The data of rhizosphere colonization indicated that the soil conditions significantly affected the rhizosphere establishment of strain 101.

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“…Under conditions in which the experiment was conducted (refer to methodology) other factors than soil properties known to influence the pathogenicity of Pythium spp. such as moisture, temperature, and light (Hendrix and Campbell, 1973;Schmidt et al, 2004) could not account much for the observed variation of disease severity between the two soil types. Increasing inoculum level reduced significantly andosols suppressiveness, but plants on ferralsols were more strongly affected.…”

Section: Article In Pressmentioning

confidence: 95%

Variation of Pythium-induced cocoyam root rot severity in response to soil type

Adiobo

Oumar

Perneel

et al. 2007

Soil Biology and Biochemistry

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In Cameroon, andosols are suspected to be suppressive to cocoyam (Xanthosoma sagittifolium) root rot disease (CRRD) caused by the Oomycete pathogen Pythium myriotylum. To determine factors involved in disease suppressiveness, andosols were studied in comparison to ferralsols known to be disease-conducive. Soil samples were collected from six sites of which three were in andosols around Mount Cameroon (Boteva, Njonji, and Ekona) and the three others in ferralsols (Bakoa, Lapkwang, and Nko'o canane). Greenhouse plant experiments were used to assess soil suppressiveness. Soils were artificially infested with two levels of P. myriotylum inoculum (100 and 300 mycelia strands g À1 soil) prior to planting cocoyam. Disease severity was significantly higher in ferralsols than in andosols. Andosols partly lost their suppressiveness as a result of autoclaving and could recover suppressiveness following recolonisation by their original microflora. Soil microbial groups implicated in the disease suppression were investigated by assessing the effect of fungicide, bactericide, and pasteurisation on andosol suppressiveness. Andosols suppressiveness was significantly reduced following pasteurisation and treatment with fungicide and bactericide. The possible influence of microbial biomass on andosol suppressiveness was investigated by comparing microbial populations of suppressive andosols to those in andosols that had lost suppressiveness. A comparative analysis of suppressive and conducive soil properties was performed to identify soil variables, which may contribute to soil suppressiveness. Soil chemical analysis results showed that organic matter content was higher in andosols than in ferralsols. In addition, the content of mineral nutrients such as Ca, K, Mg and N, was higher in andosols than in ferralsols. These soil variables negatively correlated with disease severity. By contrast, sand and clay, which were higher in ferralsols than in andosols, were positively related to disease severity. This study has confirmed the suppressive nature of andosols from Mount Cameroon to CRRD. The results suggest that high organic matter content is likely mediating P. myriotylum suppression in andosols by improving soil structure, increasing soil nutrient content and microbial biomass, and sustaining microbial activity. r

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Influence of soil type and pH on the colonisation of sugar beet seedlings by antagonistic Pseudomonas and Bacillus strains, and on their control of Pythium damping-off

Cited by 29 publications

References 64 publications

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Development of a strain-specific genomic marker for monitoring a Bacillus subtilis biocontrol strain in the rhizosphere of tomato

Variation of Pythium-induced cocoyam root rot severity in response to soil type

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