The role of clp-regulated factors in antagonism against Magnaporthe poae and biological control of summer patch disease of Kentucky bluegrass by Lysobacter enzymogenes C3

2005 ◽  
Vol 51 (8) ◽  
pp. 719-723 ◽  
Author(s):  
Donald Y Kobayashi ◽  
Gary Y Yuen
Keyword(s):  
Biological Control ◽  
Kentucky Bluegrass ◽  
Cell Suspensions ◽  
Lytic Enzymes ◽  
Control Activity ◽  
Lysobacter Enzymogenes ◽  
Magnaporthe Poae ◽  
Fungal Antagonism ◽  
Bacteria And Fungi ◽  
Patch Disease

A global regulator was previously identified in Lysobacter enzymogenes C3, which when mutated, resulted in strains that were greatly reduced in the expression of traits associated with fungal antagonism and devoid of biocontrol activity towards bipolaris leaf-spot of tall fescue and pythium damping-off of sugarbeet. A clp gene homologue belonging to the crp gene family was found to globally regulate enzyme production, antimicrobial activity, and biological control activity expressed by Lysobacter enzymogenes C3 (Kobayashi et al. 2005). Here, we report on the expansion of the biocontrol range of L. enzymogenes C3 to summer patch disease caused by Magnaporthe poae. The clp– mutant strain 5E4 was reduced in its ability to suppress summer patch disease compared with the wild-type strain C3 and was completely devoid of antifungal activity towards M. poae. Furthermore, cell suspensions of 5E4 were incapable of colonizing M. poae mycelium in a manner that was distinct for C3. Strain C3 demonstrated biosurfactant activity in cell suspensions and culture filtrates that was associated with absorption into the mycelium during the colonization process, whereas 5E4 did not. These results describe a novel interaction between bacteria and fungi that intimates a pathogenic relationship.Key words: lytic enzymes, biosurfactant, turfgrass biocontrol agent, mycopathogenic bacteria.

scholarly journals PilG is Involved in the Regulation of Twitching Motility and Antifungal Antibiotic Biosynthesis in the Biological Control Agent Lysobacter enzymogenes

2015 ◽  
Vol 105 (10) ◽  
pp. 1318-1324 ◽  
Author(s):  
Xue Zhou ◽  
Guoliang Qian ◽  
Yuan Chen ◽  
Liangcheng Du ◽  
Fengquan Liu ◽  
...  
Keyword(s):  
Biological Control ◽  
Secondary Metabolite ◽  
Fungal Pathogens ◽  
Biological Control Agent ◽  
Response Regulator ◽  
Regulatory Protein ◽  
Antibiotic Biosynthesis ◽  
Twitching Motility ◽  
Control Activity ◽  
Lysobacter Enzymogenes

Lysobacter enzymogenes strain C3 is a gliding bacterium which produces the antifungal secondary metabolite heat-stable antifungal factor (HSAF) and type IV pilus (T4P) as important mechanisms in biological control activity against fungal pathogens. To date, the regulators that control HSAF biosynthesis and T4P-dependent twitching motility in L. enzymogenes are poorly explored. In the present study, we addressed the role of pilG in the regulation of these two traits in L. enzymogenes. PilG of L. enzymogenes was found to be a response regulator, commonly known as a component of a two-component transduction system. Mutation of pilG in strain C3 abolished its ability to display spreading colony phenotype and cell movement at the colony margin, which is indicative of twitching motility; hence, PilG positively regulates twitching motility in L. enzymogenes. Mutation of pilG also enhanced HSAF production and the transcription of its key biosynthetic gene hsaf pks/nrps, suggesting that PilG plays a negative regulatory role in HSAF biosynthesis. This finding represents the first demonstration of the regulator PilG having a role in secondary metabolite biosynthesis in bacteria. Collectively, our results suggest that key ecological functions (HSAF production and twitching motility) in L. enzymogenes strain C3 are regulated in opposite directions by the same regulatory protein, PilG.

scholarly journals Draft Genome Sequence and Assembly of a Lysobacter enzymogenes Strain with Biological Control Activity against Root Knot Nematodes

2017 ◽  
Vol 5 (18) ◽  
Author(s):  
Iker Hernández ◽  
Carolina Fernàndez
Keyword(s):  
Biological Control ◽  
Genome Sequence ◽  
Biological Control Agent ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Agricultural Field ◽  
Control Activity ◽  
Root Knot Nematodes ◽  
Content Type ◽  
Lysobacter Enzymogenes

ABSTRACT Lysobacter enzymogenes strain B25, an isolate from an agricultural field, acts as a biological control agent against root knot nematodes in tomato plants. B25 also controls several fungal diseases and promotes plant growth under abiotic stress. We hereby report on the draft genome sequence and assembly of B25.

scholarly journals Roles of a Solo LuxR in the Biological Control Agent Lysobacter enzymogenes Strain OH11

2014 ◽  
Vol 104 (3) ◽  
pp. 224-231 ◽  
Author(s):  
Guoliang Qian ◽  
Feifei Xu ◽  
Vittorio Venturi ◽  
Liangcheng Du ◽  
Fengquan Liu
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Cell Aggregation ◽  
Antimicrobial Activities ◽  
Control Agent ◽  
Lytic Enzymes ◽  
Lysobacter Enzymogenes ◽  
Novel Structure ◽  
C Terminus ◽  
Visible Effect

Lysobacter enzymogenes is a ubiquitous plant-associated and environmentally friendly bacterium emerging as a novel biological control agent of plant disease. This bacterium produces diverse antifungal factors, such as lytic enzymes and a secondary metabolite (heat-stable antifungal factor [HSAF]) having antifungal activity with a novel structure and mode of action. The regulatory mechanisms for biosynthesis of antifungal factors is largely unknown in L. enzymogenes. The solo LuxR proteins have been shown to be widespread, playing important roles in plant-associated bacteria. Here, we cloned and studied a solo LuxR protein, LesR, from L. enzymogenes strain OH11. Overexpression but not deletion of lesR significantly impaired HSAF biosynthesis levels and antimicrobial activities but did not show visible effect on production of major lytic enzymes. Overexpression of lesR also led to remarkably accelerated cell aggregation and induced production of a melanin-like pigment in L. enzymogenes; these two phenotypes are mediated by the diffusible factor cell-to-cell signaling system of L. enzymogenes. The C-terminus helix-turn-helix domain was shown to be critical for several lesR-controlled functions. Overall, our study provides the first example of the roles and mechanisms of a solo LuxR protein in a plant-associated L. enzymogenes.

Potential for biological control of Phytophthora rootrot of chickpea by antagonistic root-associated bacteria

1993 ◽  
Vol 44 (4) ◽  
pp. 773 ◽  
Author(s):  
PM Myatt ◽  
PJ Dart ◽  
AC Hayward
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Pseudomonas Cepacia ◽  
Biological Control Agents ◽  
Control Activity ◽  
Phytophthora Megasperma ◽  
Associated Bacteria ◽  
Seedling Disease ◽  
Fungal Antagonism

Over 1000 bacteria were isolated from rhizospheres of chickpea (Cicer arietinum L.) and evaluated for their potential as biological control agents of Phytophthora megasperma f. sp. medicaginis root rot of chickpea in vitro. Following in vitro plate assays for fungal antagonism, initial pot assay results showed 31 isolates with the ability to limit or delay chickpea seedling disease in a pasteurized soil. The most promising isolates were identified as Pseudomonas cepacia (seven strains) and P. fluorescens (two strains). No relationship was observed between biological control activity of the bacteria and the soils, chickpea cultivars or the methods used in their isolation.

Control of cyst nematodes by Lysobacter enzymogenes strain C3 and the role of the antibiotic HSAF in the biological control activity

2018 ◽  
Vol 117 ◽  
pp. 158-163 ◽  
Author(s):  
Gary Y. Yuen ◽  
Kyle C. Broderick ◽  
Charlene C. Jochum ◽  
Carl J. Chen ◽  
Edward P. Caswell-Chen
Keyword(s):  
Biological Control ◽  
Cyst Nematodes ◽  
Control Activity ◽  
Lysobacter Enzymogenes

scholarly journals Mutagenesis of β-1,3-Glucanase Genes in Lysobacter enzymogenes Strain C3 Results in Reduced Biological Control Activity Toward Bipolaris Leaf Spot of Tall Fescue and Pythium Damping-Off of Sugar Beet

2005 ◽  
Vol 95 (6) ◽  
pp. 701-707 ◽  
Author(s):  
Jeffrey D. Palumbo ◽  
Gary Y. Yuen ◽  
C. Christine Jochum ◽  
Kristin Tatum ◽  
Donald Y. Kobayashi
Keyword(s):  
Biological Control ◽  
Sugar Beet ◽  
Tall Fescue ◽  
Leaf Spot ◽  
Mutational Analysis ◽  
Pythium Ultimum ◽  
In Vitro Assays ◽  
Damping Off ◽  
Control Activity ◽  
Lysobacter Enzymogenes

Lysobacter enzymogenes produces extracellular lytic enzymes capable of degrading the cell walls of fungi and oomycetes. Many of these enzymes, including β-1,3-glucanases, are thought to contribute to the biological control activity expressed by several strains of the species. L. enzymogenes strain C3 produces multiple extracellular β-1,3-glucanases encoded by the gluA, gluB, and gluC genes. Analysis of the genes indicates they are homologous to previously characterized genes in the related strain N4-7, each sharing >95% amino acid sequence identity to their respective counterparts. The gluA and gluC gene products encode enzymes belonging to family 16 glycosyl hydrolases, whereas gluB encodes an enzyme belonging to family 64. Mutational analysis indicated that the three genes accounted for the total β-1,3-glucanase activity detected in culture. Strain G123, mutated in all three glucanase genes, was reduced in its ability to grow in a minimal medium containing laminarin as a sole carbon source. Although strain G123 was not affected in antimicrobial activity toward Bipolaris sorokiniana or Pythium ultimum var. ultimum using in vitro assays, it was significantly reduced in biological control activity against Bipolaris leaf spot of tall fescue and Pythium damping-off of sugar beet. These results provide direct supportive evidence for the role of β-1,3-glucanases in biocontrol activity of L. enzymogenes strain C3.

Biological control of Fusarium wilt of cucumber with nonpathogenic isolates of Fusarium oxysporum

1987 ◽  
Vol 33 (5) ◽  
pp. 349-353 ◽  
Author(s):  
T. C. Paulitz ◽  
C. S. Park ◽  
R. Baker
Keyword(s):  
Biological Control ◽  
Fusarium Oxysporum ◽  
Infection Rate ◽  
Fusarium Wilt ◽  
Disease Incidence ◽  
Infection Rates ◽  
Control Activity ◽  
Significant Difference ◽  
Cucumber Roots ◽  
Linear Regressions

Nonpathogenic isolates of Fusarium oxysporum were obtained from surface-disinfested, symptomless cucumber roots grown in two raw (nonautoclaved) soils. These isolates were screened for pathogenicity and biological control activity against Fusarium wilt of cucumber in raw soil infested with Fusarium oxysporum f. sp. cucumerinum (F.o.c.). The influence of three isolates effective in inducing suppressiveness and three ineffective isolates on disease incidence over time was tested. The effective isolates reduced the infection rate (R), based on linear regressions of data transformed to loge (1/1 – y). Effective isolate C5 was added to raw soil infested with various inoculum densities of F.o.c. In treatments without C5, the increase in inoculum densities of F.o.c. decreased the incubation period of wilt disease, but there was no significant difference in infection rate among the inoculum density treatments. Isolate C5 reduced the infection rate at all inoculum densities of F.o.c. Various inoculum densities of C5 were added to raw soils infested with 1000 cfu/g of F.o.c. In the first trial, infection rates were reduced only in the treatment with 10 000 cfu/g of C5; in the second trial, infection rates were reduced in treatments with 10 000 and 30 000 cfu/g of C5.

scholarly journals Cuticular hydrocarbons discriminate cryptic Macrolophus species (Hemiptera: Miridae)

2012 ◽  
Vol 102 (6) ◽  
pp. 624-631 ◽  
Author(s):  
C. Gemeno ◽  
N. Laserna ◽  
M. Riba ◽  
J. Valls ◽  
C. Castañé ◽  
...  
Keyword(s):  
Biological Control ◽  
Cuticular Hydrocarbons ◽  
Cross Validation ◽  
Molecular Genetic ◽  
Cuticular Hydrocarbon ◽  
Hydrocarbon Composition ◽  
Dark Spot ◽  
Prediction Errors ◽  
Control Activity ◽  
Genetic Studies

AbstractMacrolophus pygmaeus is commercially employed in the biological control of greenhouse and field vegetable pests. It is morphologically undistinguishable from the cryptic species M. melanotoma, and this interferes with the evaluation of the biological control activity of M. pygmaeus. We analysed the potential of cuticular hydrocarbon composition as a method to discriminate the two Macrolophus species. A third species, M. costalis, which is different from the other two species by having a dark spot at the tip of the scutellum, served as a control. Sex, diet and species, all had significant effects in the cuticular hydrocarbon profiles, but the variability associated to sex or diet was smaller than among species. Discriminant quadratic analysis of cuticular hydrocarbons confirmed the results of previous molecular genetic studies and showed, using cross-validation methods, that M. pygmaeus can be discriminated from M. costalis and M. melanotoma with prediction errors of 6.75% and 0%, respectively. Therefore, cuticular hydrocarbons can be used to separate M. pygmaeus from M. melanotoma reliably.

scholarly journals Mechanistically Compatible Mixtures of Bacterial Antagonists Improve Biological Control of Fire Blight of Pear

2011 ◽  
Vol 101 (1) ◽  
pp. 113-123 ◽  
Author(s):  
V. O. Stockwell ◽  
K. B. Johnson ◽  
D. Sugar ◽  
J. E. Loper
Keyword(s):  
Biological Control ◽  
Plant Disease ◽  
Fire Blight ◽  
Biological Control Agent ◽  
Field Trials ◽  
Control Agent ◽  
Extracellular Protease ◽  
Peptide Antibiotics ◽  
Biological Control Agents ◽  
Control Activity

Mixtures of biological control agents can be superior to individual agents in suppressing plant disease, providing enhanced efficacy and reliability from field to field relative to single biocontrol strains. Nonetheless, the efficacy of combinations of Pseudomonas fluorescens A506, a commercial biological control agent for fire blight of pear, and Pantoea vagans strain C9-1 or Pantoea agglomerans strain Eh252 rarely exceeds that of individual strains. A506 suppresses growth of the pathogen on floral colonization and infection sites through preemptive exclusion. C9-1 and Eh252 produce peptide antibiotics that contribute to disease control. In culture, A506 produces an extracellular protease that degrades the peptide antibiotics of C9-1 and Eh252. We hypothesized that strain A506 diminishes the biological control activity of C9-1 and Eh252, thereby reducing the efficacy of biocontrol mixtures. This hypothesis was tested in five replicated field trials comparing biological control of fire blight using strain A506 and A506 aprX::Tn5, an extracellular protease-deficient mutant, as individuals and combined with C9-1 or Eh252. On average, mixtures containing A506 aprX::Tn5 were superior to those containing the wild-type strain, confirming that the extracellular protease of A506 diminished the biological control activity of C9-1 and Eh252 in situ. Mixtures of A506 aprX::Tn5 and C9-1 or Eh252 were superior to oxytetracycline or single biocontrol strains in suppressing fire blight of pear. These experiments demonstrate that certain biological control agents are mechanistically incompatible, in that one strain interferes with the mechanism by which a second strain suppresses plant disease. Mixtures composed of mechanistically compatible strains of biological control agents can suppress disease more effectively than individual biological control agents.

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