Potential Biological Control Activity and Genetic Diversity of Pseudomonas syringae pv. syringae Strains

2005 ◽  
Vol 153 (11-12) ◽  
pp. 654-666 ◽  
Author(s):  
G. Cirvilleri ◽  
A. Bonaccorsi ◽  
G. Scuderi ◽  
M. Scortichini
Keyword(s):  
Genetic Diversity ◽  
Biological Control ◽  
Pseudomonas Syringae ◽  
Control Activity

scholarly journals Genetic Diversity and Biological Control Activity of Novel Species of Closely Related Pseudomonads Isolated from Wheat Field Soils in South Australia

2000 ◽  
Vol 66 (4) ◽  
pp. 1609-1616 ◽  
Author(s):  
Ian L. Ross ◽  
Younes Alami ◽  
Paul R. Harvey ◽  
Wafa Achouak ◽  
Maarten H. Ryder
Keyword(s):  
Genetic Diversity ◽  
Biological Control ◽  
Novel Species ◽  
Acid Methyl Ester ◽  
South Australia ◽  
Gaeumannomyces Graminis ◽  
Control Activity ◽  
Wheat Field ◽  
Field Soils ◽  
Take All

ABSTRACT Rhizobacteria closely related to two recently described species of pseudomonads, Pseudomonas brassicacearum andPseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in South Australia. Isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against P. brassicacearum. A subset of 42 isolates were characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA), BIOLOG analysis, and gas chromatography-fatty acid methyl ester (GC-FAME) analysis and separated into closely related phenetic groups. More than 75% of isolates tested by ARDRA were found to have >95% similarity to either Pseudomonas corrugata or P. brassicacearum-P. thivervalensis type strains, and all isolates had >90% similarity to either type strain. BIOLOG and GC-FAME clustering showed a >70% match to ARDRA profiles. Strains representing different ARDRA groups were tested in two soil types for biological control activity against the soilborne plant pathogen Gaeumannomyces graminis var. tritici, the causative agent of take-all of wheat and barley. Three isolates out of 11 significantly reduced take-all-induced root lesions on wheat plants grown in a red-brown earth soil. Only one strain, K208, was consistent in reducing disease symptoms in both the acidic red-brown earth and a calcareous sandy loam. Results from this study indicate that P. brassicacearum and P. thivervalensis are present in Australian soils and that a level of genetic diversity exists within these two novel species but that this diversity does not appear to be related to geographic distribution. The result of the glasshouse pot trial suggests that some isolates of these species may have potential as biological control agents for plant disease.

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.

scholarly journals Immobilized Bacillus subtilis by ionic gelation as biocontrol alternative of Fusarium oxysporum f.sp. lycopersici

2018 ◽  
Author(s):  
Castañeda Alvarez Estefania ◽  
Sánchez Leal Ligia
Keyword(s):  
Biological Control ◽  
Bacillus Subtilis ◽  
Fusarium Oxysporum ◽  
Sodium Alginate ◽  
Ionic Gelation ◽  
Cellular Viability ◽  
Market Demand ◽  
Control Activity ◽  
Pests And Diseases

For farmers the use of agrochemicals is the preferred method to control pests and diseases. Considering the market demand for biological control products, the encapsulation could be a competent alternative to current commercial formulations for cellular viability and controlled release. The purpose of this study was to use ionic gelation with sodium alginate, starch and maltodextrin to immobilize Bacillus subtilis and to evaluate the biocontrol effect against Fusarium oxysporum f. sp. lycopersici in vitro. The matrix with a concentration of 2% sodium alginate, 1% starch, and 1% maltodextrin is a suitable method for cellular viability and biological control activity against Fusarium oxysporum f. sp. lycopersici, with a reduction of mycelial growth of 49.6% and a survival rate for Bacillus subtilis of 98.05% (p less than 0.0001).The use of immobilized bacteria as biological control agents are sustainable and effective bio-inputs that could be used at industrial scale and benefit the tomato crops against attack by Fusarium oxysporum f. sp. lycopersici.

scholarly journals Biological Control Activity of Two Isolates of Pseudomonas fluorescens against Rice Sheath Blight

2006 ◽  
Vol 22 (3) ◽  
pp. 289-294 ◽  
Author(s):  
Gyung-Ja Choi ◽  
Jin-Cheol Kim ◽  
Eun-Jin Park ◽  
Yong-Ho Choi ◽  
Kyoung-Soo Jang ◽  
...  
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Sheath Blight ◽  
Rice Sheath Blight ◽  
Control Activity

scholarly journals Methyl Salicylate Fails to Enhance Arthropod Predator Abundance or Predator to Pest Ratios in Cotton

2021 ◽  
Author(s):  
Steven E Naranjo ◽  
James R Hagler ◽  
John A Byers
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Methyl Salicylate ◽  
Production Systems ◽  
Control Function ◽  
Conservation Biological Control ◽  
Cotton Production ◽  
Control Activity ◽  
Synthetic Chemicals

Abstract Conservation biological control is a fundamental tactic in integrated pest management (IPM). Greater biological control services can be achieved by enhancing agroecosystems to be more favorable to the presence, survival, and growth of natural enemy populations. One approach that has been tested in numerous agricultural systems is the deployment of synthetic chemicals that mimic those produced by the plant when under attack by pests. These signals may attract arthropod natural enemies to crop habitats and thus potentially improve biological control activity locally. A 2-yr field study was conducted in the cotton agroecosystem to evaluate the potential of synthetic methyl salicylate (MeSA) to attract native arthropod natural enemies and to enhance biological control services on two key pests. Slow-release packets of MeSA were deployed in replicated cotton plots season long. The abundance of multiple taxa of natural enemies and two major pests were monitored weekly by several sampling methods. The deployment of MeSA failed to increase natural enemy abundance and pest densities did not decline. Predator to prey ratios, used as a proxy to estimate biological control function, also largely failed to increase with MeSA deployment. One exception was a season-long increase in the ratio of Orius tristicolor (White) (Hemiptera: Anthocoridae) to Bemisia argentifolii Bellows and Perring (= Bemisia tabaci MEAM1) (Hemiptera: Aleyrodidae) adults within the context of biological control informed action thresholds. Overall results suggest that MeSA would not likely enhance conservation biological control by the natural enemy community typical of U.S. western cotton production systems.

Russian-olive (Elaeagnus angustifolia) genetic diversity in the western United States and implications for biological control

2019 ◽  
Vol 12 (02) ◽  
pp. 89-96 ◽  
Author(s):  
John F. Gaskin ◽  
Jose A. Andrés ◽  
Steven M. Bogdanowicz ◽  
Kimberly R. Guilbault ◽  
Ruth A. Hufbauer ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Biological Control ◽  
Biological Control Agent ◽  
Isolation By Distance ◽  
Western United States ◽  
Elaeagnus Angustifolia ◽  
Genetic Cluster ◽  
Russian Olive ◽  
Geographic Population

AbstractInvasions can be genetically diverse, and that diversity may have implications for invasion management in terms of resistance or tolerance to control methods. We analyzed the population genetics of Russian-olive (Elaeagnus angustifoliaL.), an ecologically important and common invasive tree found in many western U.S. riparian areas. We found three cpDNA haplotypes and, using 11 microsatellite loci, identified three genetic clusters in the 460 plants from 46 populations in the western United States. We found high levels of polymorphism in the microsatellites (5 to 15 alleles per locus; 106 alleles total). Our native-range sampling was limited, and we did not find a genetic match for the most common cpDNA invasive haplotype or a strong confirmation of origin for the most common microsatellite genetic cluster. We did not find geographic population structure (isolation by distance) across the U.S. invasion, but we did identify invasive populations that had the most diversity, and we suggest these as choices for initial biological control–release monitoring. Accessions from each genetic cluster, which coarsely represent the range of genetic diversity found in the invasion, are now included in potential classical biological control agent efficacy testing.

scholarly journals Draft Genome Resources Sequences of Six Pseudomonas syringae pv. actinidiae Strains Isolated from Actinidia chinensis var. deliciosa Leaves in Portugal

2020 ◽  
pp. PHYTO-05-20-018
Author(s):  
Aitana Ares ◽  
Marta Tacão ◽  
Daniela Figueira ◽  
Eva Garcia ◽  
Joana Costa
Keyword(s):  
Genetic Diversity ◽  
Pseudomonas Syringae ◽  
Draft Genome ◽  
Clonal Expansion ◽  
Average Nucleotide Identity ◽  
Actinidia Chinensis ◽  
Valuable Resource ◽  
Genetic Population ◽  
Evolutionary Studies ◽  
Reference Strains

Pseudomonas syringae pv. actinidiae is a quarantine bacterium affecting all the Portuguese main areas of kiwifruit production. We report the draft genome of six P. syringae pv. actinidiae strains isolated from symptomatic leaves of Actinidia chinensis var. deliciosa in a study that determined the genetic population structure of the endophytic and epiphytic populations in two consecutive seasons. Average nucleotide identity values were above 99% similarity with reference strains from P. syringae pv. actinidiae biovar 3. The genomic differences found between these strains confirm the genetic diversity described for P. syringae pv. actinidiae population in Portugal. Furthermore, data provide evidence that the initial clonal expansion of P. syringae pv. actinidiae in Europe was followed by a genomic diversification constituting a valuable resource for epidemiological and evolutionary studies, namely when adopting strategies for epidemics management.

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