Pseudomonas spp. diversity is negatively associated with suppression of the wheat take-all pathogen

Abstract Biodiversity and ecosystem functioning research typically shows positive diversity- productivity relationships. However, local increases in species richness can increase competition within trophic levels, reducing the efficacy of intertrophic level population control. Pseudomonas spp. are a dominant group of soil bacteria that play key roles in plant growth promotion and control of crop fungal pathogens. Here we show that Pseudomonas spp. richness is positively correlated with take-all disease in wheat and with yield losses of ~3 t/ha in the field. We modeled the interactions between Pseudomonas and the take-all pathogen in abstract experimental microcosms and show that increased bacterial genotypic richness escalates bacterial antagonism and decreases the ability of the bacterial community to inhibit growth of the take-all pathogen. Future work is required to determine the generality of these negative biodiversity effects on different media and directly at infection zones on root surfaces. However, the increase in competition between bacteria at high genotypic richness and the potential loss of fungal biocontrol activity highlights an important mechanism to explain the negative Pseudomonas diversity-wheat yield relationship we observed in the field. Together our results suggest that the effect of biodiversity on ecosystem functioning can depend on both the function and trophic level of interest.

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Biological Control of Take-All and Growth Promotion in Wheat by Pseudomonaschlororaphis YB-10

Pathogens ◽

10.3390/pathogens10070903 ◽

2021 ◽

Vol 10 (7) ◽

pp. 903

Author(s):

Wen Xu ◽

Lingling Xu ◽

Xiaoxu Deng ◽

Paul H. Goodwin ◽

Mingcong Xia ◽

...

Keyword(s):

Growth Promotion ◽

Wheat Yield ◽

Gaeumannomyces Graminis ◽

Rrna Gene ◽

Pseudomonas Chlororaphis ◽

Wheat Seed ◽

Mycelium Growth ◽

Coating Agent ◽

Gaeumannomyces Graminis Var Tritici ◽

Take All

Wheat is a worldwide staple food crop, and take-all caused by Gaeumannomyces graminis var. tritici can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was isolated from wheat rhizospheric soil and identified as Pseudomonas chlororaphis by morphology and 16S rRNA gene sequencing. Pseudomonas chlororaphis YB-10 had extracellular protease and cellulase activities and strongly inhibited the mycelium growth of Gaeumannomyces graminis var. tritici in dual cultures. Up to 87% efficacy of Pseudomonas chlororaphis YB-10 in controlling the take-all of seedlings was observed in pot experiments when wheat seed was coated with the bacterium. Pseudomonas chlororaphis YB-10 was also positive for indole acetic acid (IAA) and siderophore production, and coating wheat seed with the bacterium significantly promoted the growth of seedlings at 107 and 108 CFU/mL. Furthermore, treatment with Pseudomonas chlororaphis YB-10 increased activities of the wheat defense-related enzymes POD, SOD, CAT, PAL and PPO in seedlings, indicating induced resistance against pathogens. Overall, Pseudomonas chlororaphis YB-10 is a promising new seed-coating agent to both promote wheat growth and suppress take-all.

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Genome Mining and Evaluation of the Biocontrol Potential of Pseudomonas fluorescens BRZ63, a New Endophyte of Oilseed Rape (Brassica napus L.) against Fungal Pathogens

International Journal of Molecular Sciences ◽

10.3390/ijms21228740 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8740

Author(s):

Daria Chlebek ◽

Artur Pinski ◽

Joanna Żur ◽

Justyna Michalska ◽

Katarzyna Hupert-Kocurek

Keyword(s):

Brassica Napus ◽

Plant Growth ◽

Pseudomonas Fluorescens ◽

Oilseed Rape ◽

Plant Growth Promotion ◽

Fungal Pathogens ◽

Growth Promotion ◽

Genome Mining ◽

Plant Colonization ◽

Brassica Napus L

Endophytic bacteria hold tremendous potential for use as biocontrol agents. Our study aimed to investigate the biocontrol activity of Pseudomonas fluorescens BRZ63, a new endophyte of oilseed rape (Brassica napus L.) against Rhizoctonia solani W70, Colletotrichum dematium K, Sclerotinia sclerotiorum K2291, and Fusarium avenaceum. In addition, features crucial for biocontrol, plant growth promotion, and colonization were assessed and linked with the genome sequences. The in vitro tests showed that BRZ63 significantly inhibited the mycelium growth of all tested pathogens and stimulated germination and growth of oilseed rape seedlings treated with fungal pathogens. The BRZ63 strain can benefit plants by producing biosurfactants, siderophores, indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia as well as phosphate solubilization. The abilities of exopolysaccharide production, autoaggregation, and biofilm formation additionally underline its potential to plant colonization and hence biocontrol. The effective colonization properties of the BRZ63 strain were confirmed by microscopy observations of EGFP-expressing cells colonizing the root surface and epidermal cells of Arabidopsis thaliana Col-0. Genome mining identified many genes related to the biocontrol process, such as transporters, siderophores, and other secondary metabolites. All analyses revealed that the BRZ63 strain is an excellent endophytic candidate for biocontrol of various plant pathogens and plant growth promotion.

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Pseudomonads contribute to regulation ofPratylenchus penetrans(Nematoda) populations on apple

Canadian Journal of Microbiology ◽

10.1139/cjm-2018-0040 ◽

2018 ◽

Vol 64 (11) ◽

pp. 775-785 ◽

Cited By ~ 2

Author(s):

Tristan T. Watson ◽

Tom A. Forge ◽

Louise M. Nelson

Keyword(s):

Pseudomonas Fluorescens ◽

Protease Activity ◽

Fungal Pathogens ◽

Plant Biomass ◽

Growth Promotion ◽

In Vitro Growth ◽

Pratylenchus Penetrans ◽

Pseudomonas Spp ◽

Orchard Soil

Inoculation with antagonistic soil microorganisms has shown potential to suppress replant disease of apple in orchard soils. Pseudomonas spp. may have the potential to reduce Pratylenchus penetrans populations on apple. Pseudomonas spp. were isolated from the rhizosphere of sweet cherry and screened for antagonistic characteristics. Two highly antagonistic Pseudomonas isolates, P10-32 and P10-42, were evaluated for growth promotion of apple seedlings, suppression of P. penetrans populations, and root colonization in soil from three orchards. During the isolate screening, Pseudomonas fluorescens P10-32 reduced in vitro growth of fungal pathogens, had protease activity, had capacity to produce pyrrolnitrin, suppressed P. penetrans populations, and increased plant biomass. Pseudomonas fluorescens P10-42 reduced in vitro growth of fungal pathogens, had protease activity, suppressed P. penetrans populations, and increased plant biomass. In potted orchard soil, inoculating apple with P. fluorescens P10-32 suppressed P. penetrans populations in one of the three soils examined. Inoculation with P. fluorescens P10-42 improved plant growth in two of the soils and suppressed P. penetrans abundance in one soil. In one of the soils, P. fluorescens P10-42 was detected on the roots 56 days postinoculation. Overall, we conclude that Pseudomonas spp. play a role in suppressing P. penetrans on apple in orchard soil.

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Plant growth promotion of wheat inoculated with Penicillium radicum sp. nov.

Soil Research ◽

10.1071/s96040 ◽

1997 ◽

Vol 35 (2) ◽

pp. 291 ◽

Cited By ~ 57

Author(s):

M. A. Whitelaw ◽

T. J. Harden ◽

G. L. Bender

Keyword(s):

Triticum Aestivum ◽

Plant Growth ◽

Plant Growth Promotion ◽

Field Trial ◽

Phosphate Uptake ◽

Growth Promotion ◽

Wheat Yield ◽

Low Ph ◽

Negative Interaction ◽

Phosphate Solubilisation

A phosphate-solubilising isolate of Penicillium radicum (sp. nov.) was used to inoculate wheat (Triticum aestivum cv. Dollarbird) in a glasshouse experiment and a field trial, using low pH soils at 5 levels of phosphate application. When data for all phosphate application levels were combined, inoculation by P. radicum resulted in 14% increases in wheat yield in the field trial and increases in both phosphate uptake (10%) and yield (9%) in the glasshouse. In the glasshouse, the response to inoculation was higher at the nil phosphate application level (17%) than for the combined phosphate application levels (9%). This negative interaction indicates that growth promotion could be partially due to soil phosphate solubilisation by the fungus, with a greater response for soils with lower available P. However, other plant-growth promotion mechanisms may also be involved.

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Comparing methods for building trophic spectra of ecological data

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp249 ◽

2009 ◽

Vol 67 (3) ◽

pp. 426-434 ◽

Cited By ~ 10

Author(s):

Simone Libralato ◽

Cosimo Solidoro

Keyword(s):

Systematic Review ◽

Distribution Function ◽

Ecosystem Functioning ◽

Original Data ◽

Trophic Levels ◽

Emergent Properties ◽

Density Functions ◽

Normal Density ◽

Density Distribution Function ◽

Ecological Data

Abstract Libralato, S., and Solidoro, C. 2010. Comparing methods for building trophic spectra of ecological data. – ICES Journal of Marine Science, 67: 426–434. The distribution of biomass, production, and catches over trophic levels (TLs) of the foodweb has been shown theoretically and empirically to provide powerful insights into ecosystem functioning and the effects of fishing. One approach for building trophic spectra of ecological data is based on smoothing original data and assuming zeroes when no values are available for a TL (smoothing-based method). An alternative method is proposed, based on the distribution of ecological data according to density functions (dispersion-based method), and a systematic review of the different alternatives is presented. Six different methods for building trophic spectra, i.e. the smoothing-based and five alternative forms for dispersion-based (using normal, lognormal, and Weibull distributions, also including shifted lognormal and Weibull with zero at TL 2), were applied to ecological properties (i.e. production, biomass, and catches) derived for 24 foodweb models to test their relative performance. The smoothing-based method suffers from the lack of consistency with original data and from unrealistic emergent properties, such as transfer efficiency. The analysis demonstrates the advantages of the dispersion-based method for overcoming these issues and shows, using transfer efficiencies estimated from the models (flow-based estimates) as a reference, that the normal density distribution function performs better.

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Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

10.7287/peerj.preprints.540v3 ◽

2015 ◽

Author(s):

Jonathan S Lefcheck ◽

J. Emmett Duffy

Keyword(s):

Species Richness ◽

Food Web ◽

Functional Diversity ◽

Ecosystem Functioning ◽

Structural Equation ◽

A Priori ◽

Functional Trait ◽

Trophic Levels ◽

Equation Modeling ◽

Experimental Investigations

The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori altered functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within multiple levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on general linear mixed effects models. Combining inferences from 8 traits into a single multivariate index increased prediction accuracy of these models relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context.

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Multitrophic functional diversity predicts ecosystem functioning in experimental assemblages of estuarine consumers

10.7287/peerj.preprints.540v2 ◽

2015 ◽

Author(s):

Jonathan S Lefcheck ◽

J. Emmett Duffy

Keyword(s):

Species Richness ◽

Food Web ◽

Functional Diversity ◽

Ecosystem Functioning ◽

Structural Equation ◽

A Priori ◽

Functional Trait ◽

Trophic Levels ◽

Equation Modeling ◽

Experimental Investigations

The use of functional traits to explain how biodiversity affects ecosystem functioning has attracted intense interest, yet few studies have a priori manipulated functional diversity, especially in multitrophic communities. Here, we manipulated multivariate functional diversity of estuarine grazers and predators within two levels of species richness to test how species richness and functional diversity predicted ecosystem functioning in a multitrophic food web. Community functional diversity was a better predictor than species richness for the majority of ecosystem properties, based on general linear mixed effects models. Combining inferences from 8 traits into a single multivariate index increased prediction accuracy of these properties relative to any individual trait. Structural equation modeling revealed that functional diversity of both grazers and predators was important in driving final biomass within and between trophic levels, with stronger effects observed for predators. We also show that different species drove different ecosystem responses, with evidence for both sampling effects and complementarity. Our study extends experimental investigations of functional trait diversity to a multilevel food web, and demonstrates that functional diversity can be more accurate and effective than species richness in predicting community biomass in a food web context.

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Trophic interactions among the heterotrophic components of plankton in man-made peat pools

Journal of Limnology ◽

10.4081/jlimnol.2017.1594 ◽

2017 ◽

Author(s):

Michał Niedźwiecki ◽

Malgorzata Adamczuk ◽

Tomasz Mieczan

Keyword(s):

Carbon Flux ◽

Ecosystem Functioning ◽

Trophic Levels ◽

Environmental Drivers ◽

Heterotrophic Nanoflagellates ◽

Peat Bogs ◽

Trophic Groups ◽

Comprehensive Knowledge ◽

Different Types ◽

Freshwater Habitats

<p>Man-made peat pools are permanent freshwater habitats developed due to non-commercial man-made peat extraction. Yet, they have not been widely surveyed in terms of ecosystem functioning, mainly regarding the complexity of heterotrophic components of the plankton. In this study we analysed distribution and trophic interrelations among heterotrophic plankton in man-made peat pools located in different types of peatbogs. We found that peat pools showed extreme differences in environmental conditions that occurred to be important drivers of distribution of microplankton and metazooplankton. Abundance of bacteria and protozoa showed significant differences, whereas metazooplankton was less differentiated in density among peat pools. In all peat pools stress-tolerant species of protozoa and metazoa were dominant. In each peat pool five trophic functional groups were distinguished. The abundance of lower functional trophic groups (bacteria, heterotrophic nanoflagellates (HNF) and ciliates feeding on bacteria and HNF) was weakly influenced by environmental drivers and was highly stable in all peat pool types. Higher fu<span style="text-decoration: underline;">n</span>ctional trophic groups (naupli, omnivorous and carnivorous ciliates, cladocerans, adult copepods and copepodites) were strongly influenced by environmental variables and exhibited lower stability. Our study contributes to comprehensive knowledge of the functioning of peat bogs, as our results have shown that peat pools are characterized by high stability of the lowest trophic levels, which can be crucial for energy transfer and carbon flux through food webs.</p>

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Isolation, selection, and characterization of beneficial rhizobacteria from pea, lentil, and chickpea grown in western Canada

Canadian Journal of Microbiology ◽

10.1139/w08-008 ◽

2008 ◽

Vol 54 (4) ◽

pp. 248-258 ◽

Cited By ~ 72

Author(s):

Russell K. Hynes ◽

Grant C.Y. Leung ◽

Danielle L.M. Hirkala ◽

Louise M. Nelson

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Fungal Pathogens ◽

Crop Production ◽

Growth Promotion ◽

Profile Analysis ◽

Acc Deaminase ◽

Plant Growth Promoting ◽

Growth Promoting

The use of beneficial soil microorganisms as agricultural inputs for improved crop production requires selection of rhizosphere-competent microorganisms with plant growth-promoting attributes. A collection of 563 bacteria originating from the roots of pea, lentil, and chickpea grown in Saskatchewan was screened for several plant growth-promoting traits, for suppression of legume fungal pathogens, and for plant growth promotion. Siderophore production was detected in 427 isolates (76%), amino-cyclopropane-1-carboxylic acid (ACC) deaminase activity in 29 isolates (5%), and indole production in 38 isolates (7%). Twenty-six isolates (5%) suppressed the growth of Pythium sp. strain p88-p3, 40 isolates (7%) suppressed the growth of Fusarium avenaceum , and 53 isolates (9%) suppressed the growth of Rhizoctonia solani CKP7. Seventeen isolates (3%) promoted canola root elongation in a growth pouch assay, and of these, 4 isolates promoted the growth of lentil and one isolate promoted the growth of pea. Fatty acid profile analysis and 16S rRNA sequencing of smaller subsets of the isolates that were positive for the plant growth-promotion traits tested showed that 39%–42% were members of the Pseudomonadaceae and 36%–42% of the Enterobacteriaceae families. Several of these isolates may have potential for development as biofertilizers or biopesticides for western Canadian legume crops.

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