A Three-Way Transcriptomic Interaction Study of a Biocontrol Agent (Clonostachys rosea), a Fungal Pathogen (Helminthosporium solani), and a Potato Host (Solanum tuberosum).

PubMed

Lysøe, Erik; Dees, Merete W; Brurberg, May Bente

2017-08-01

Helminthosporium solani causes silver scurf, which affects the quality of potato. The biocontrol agent Clonostachys rosea greatly limited the severity of silver scurf symptoms and amount of H. solani genomic DNA in laboratory experiments. Transcriptomic analysis during interaction showed that H. solani gene expression was highly reduced when coinoculated with the biocontrol agent C. rosea, whereas gene expression of C. rosea was clearly boosted as a response to the pathogen. The most notable upregulated C. rosea genes were those encoding proteins involved in cellular response to oxidative stress, proteases, G-protein signaling, and the methyltransferase LaeA. The most notable potato response to both fungi was downregulation of defense-related genes and mitogen-activated protein kinase kinase kinases. At a later stage, this shifted, and most potato defense genes were turned on, especially those involved in terpenoid biosynthesis when H. solani was present. Some biocontrol-activated defense-related genes in potato were upregulated during early interaction with C. rosea alone that were not triggered by H. solani alone. Our results indicate that the reductions of silver scurf using C. rosea are probably due to a combination of mechanisms, including mycoparasitism, biocontrol-activated stimulation of plant defense mechanisms, microbial competition for nutrients, space, and antibiosis.

Conjunctively screening of biocontrol agents (BCAs) against fusarium root rot and fusarium head blight caused by Fusarium graminearum.

PubMed

Wang, Lu-Yao; Xie, Yue-Shen; Cui, Yuan-Yu; Xu, Jianjun; He, Wei; Chen, Huai-Gu; Guo, Jian-Hua

2015-08-01

Fusarium root-rot and fusarium head blight are plant diseases caused by Fusarium sp. in different growth periods of wheat, bring heavy losses to crop production in China. This research is aiming to screen biocontrol agents conjunctively for controlling these two diseases at the same time, as well as evaluate our previous BCAs (Biological Control Agents) screening strategies in more complex situation, considering biocontrol is well concerned as an environmental-friendly plant disease controlling method. Totally 966 bacterial isolates were screened from different parts of wheat tissues, of which potential biocontrol values were detected according to their abilities in antagonism inhibition and secreting extracellular hydrolytic enzyme. Biocontrol tests against fusarium root rot and fusarium head blight were carried out on 37 bacterial isolates with potential biocontrol capacity after pre-selection through ARDRA- and BOX-PCR analysis on strains with high assessment points. We acquired 10 BCAs with obvious biocontrol efficacy (more than 40%) in greenhouse and field tests. Pseudomonas fluorescens LY1-8 performed well in both two tests (biocontrol efficacy: 44.62% and 58.31%), respectively. Overall, correlation coefficient is 0.720 between assessment values of 37 tested BCA strains and their biocontrol efficacy in trails against fusarium root rot; correlation coefficient is 0.806 between their assessment values and biocontrol efficacy in trails against fusarium head blight. We acquired 10 well-performed potential BCAs, especially P. fluorescens LY1-8 displayed good biocontrol capacity against two different diseases on wheat. Biocontrol efficacies results in both greenhouse and field tests showed high positive correlation with assessment values (0.720 and 0.806), suggesting that the BCAs screening and assessing strategy previously developed in our lab is also adaptable for conjunctively screening BCAs for controlling both root and shoot diseases on wheat caused by same fungal pathogen. Copyright © 2015 Elsevier GmbH. All rights reserved.

Aflatoxins: mechanisms of inhibition by antagonistic plants and microorganisms

USDA-ARS?s Scientific Manuscript database

Aflatoxins are a family of toxic fungal secondary metabolites. The rapid expansion in our knowledge about inhibition of aflatoxin biosynthesis by compounds from plants and microorganisms has enabled us to utilize them as potential biocontrol agents. Substantial efforts have been devoted to identify ...

Surfactin triggers biofilm formation of Bacillus subtilis in melon phylloplane and contributes to the biocontrol activity.

PubMed

Zeriouh, Houda; de Vicente, Antonio; Pérez-García, Alejandro; Romero, Diego

2014-07-01

The biocontrol activity of many Bacillus species has been traditionally related to the direct antagonism of pathogens. In previous works, we reported that B. subtilis strain UMAF6614 was an efficient biocontrol agent that produced bacillomycin, fengycin and surfactin lipopeptides. Bacillomycins and fengycins were shown to have antagonistic activity towards fungal and bacterial pathogens of cucurbits; however, the functionality of surfactin remained unclear. In this study, the role of surfactin in the biocontrol activity of this strain was investigated. We observed that a deficiency in surfactin production led to a partial reduction of disease suppression by this biocontrol agent, which coincided with a defect in biofilm formation and the colonization of the melon phylloplane. These effects were due to a dramatic reduction in the production of exopolysaccharide and the TasA protein, which are the two major components of the extracellular matrix. We propose that the biocontrol activity of this strain is the result of the coordinated action of the three families of lipopeptides. B. subtilis UMAF6614 produces surfactin to trigger biofilm formation on melon phylloplane, which ensures the long-term persistence and the adequate secretion of suppressive lipopeptides, bacillomycins and fengycins, which efficiently target pathogens. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Genomic Analysis of Bacillus sp. Strain B25, a Biocontrol Agent of Maize Pathogen Fusarium verticillioides.

PubMed

Douriet-Gámez, Nadia R; Maldonado-Mendoza, Ignacio E; Ibarra-Laclette, Enrique; Blom, Jochen; Calderón-Vázquez, Carlos L

2018-03-01

Bacillus sp. B25 is an effective biocontrol agent against the maize pathogenic fungus Fusarium verticillioides (Fv). Previous in vitro assays have shown that B25 has protease, glucanase, and chitinase activities and siderophores production; however, specific mechanisms by which B25 controls Fv are still unknown. To determine the genetic traits involved in biocontrol, B25 genome was sequenced and analyzed. B25 genome is composed of 5,113,413 bp and 5251 coding genes. A multilocus phylogenetic analysis (MLPA) suggests that B25 is closely related to the Bacillus cereus group and a high percentage (70-75%) of the genetic information is conserved between B25 and related strains, which include most of the genes associated to fungal antagonism. Some of these genes are shared with some biocontrol agents of the Bacillus genus and less with Pseudomonas and Serratia strains. We performed a genomic comparison between B25 and five Bacillus spp., Pseudomonas and Serratia strains. B25 contains genes involved in a wide variety of antagonistic mechanisms including chitinases, glycoside hydrolases, siderophores, antibiotics, and biofilm production that could be implicated in root colonization. Also, 24 genomic islands and 3 CRISPR sequences were identified in the B25 genome. This is the first comparative genome analysis between strains belonging to the B. cereus group and biocontrol agents of phytopathogenic fungi. These results are the starting point for further studies on B25 gene expression during its interaction with Fv.

Effect of seed pelleting with biocontrol agents on growth and colonisation of roots of mungbean by root-infecting fungi.

PubMed

Ramzan, Nadia; Noreen, Nayara; Perveen, Zahida; Shahzad, Saleem

2016-08-01

Mungbean (Vigna radiata (L.) Wilczek) is a leguminous pulse crop that is a major source of proteins, vitamins and minerals. Root-infecting fungi produce severe plant diseases like root rot, charcoal rot, damping-off and stem rot. The soil-borne pathogens can be controlled by chemicals, but these chemicals have several negative effects. Use of microbial antagonist such as fungi and bacteria is a safe, effective and eco-friendly method for the control of many soil-borne pathogens. Biological control agents promote plant growth and develop disease resistance. Application of bacteria and fungi as seed dressing suppressed the root-infecting fungi on leguminous crops. Seeds of mungbean were pelleted with different biocontrol agents to determine their effect on plant growth and colonisation of roots by root-infecting fungi, viz. Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani and Sclerotium rolfsii. Treatment of mungbean seeds with fungal antagonists showed more shoot and root length as compared to bacterial antagonists, whereas seed treated with bacterial antagonists showed maximum shoot and root weight. Trichoderma harzianum and Bacillus subtilis were the best among all the biocontrol agents since they provided the highest plant growth and greater reduction in root colonisation by all root-infecting fungi. Bacillus cereus, Trichoderma virens, Pseudomonas fluorescens and Micrococcus varians were also effective against root-infecting fungi but to a lesser extent. T. harzianum, T. virens, B. subtilis and P. fluorescens were found to be best among all biocontrol agents. The root-infecting fungi can be controlled by pelleting seeds with biocontrol agents as it is safe and effective method. Additionally, plant growth was promoted more by this method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Biofertilization and Biocontrol in the fight against soilborne fungal root pathogens in Australian soils

NASA Astrophysics Data System (ADS)

Cooper, Sarah; Agnew, Linda; Pereg, Lily

2015-04-01

Control of soilborne fungal root pathogens that severely compromise cotton production and other crops worldwide has historically been through the use of synthetic fungicides and fertilizers, these often have hazardous implications for environmental and soil health. The search for sustainable alternatives has lead to heightened interest in biocontrol, using soil microorganisms that suppress the growth of phytopathogens directly and biofertilization, the use of microorganisms to increasing the nutrient availability in soils, increasing seedling vigour. Soil properties and consequently soil microbial properties are strongly impacted by agricultural practices, therefore we are isolating indigenous microorganisms from soils collected from ten different geographical locations within the Australian cotton-growing region. These differ vastly in soil type and management practices. Soils are being analysed to compare the abundance of phosphate solubilising, auxin producing and nitrogen cycling bacteria. Rhizospheric bacteria capable of plant growth promoting through a multiple actions are being isolated. In addition, a method for isolating soilborne fungal suppressive microbes directly from soil samples has been designed and is currently being used. Comparisons between agricultural practices and the plant growth promoting microbial component of soil microbiome will be reported on. We will discuss the microbial isolates identified, their modes of action and their potential use as biocontrol agents and/or biofertilizers in Australian cotton growing soils.

Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens ▿

PubMed Central

Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

2011-01-01

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible. PMID:21685161

Pseudomonas fluorescens F113 mutant with enhanced competitive colonization ability and improved biocontrol activity against fungal root pathogens.

PubMed

Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

2011-08-01

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible.

Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease.

PubMed

Hanada, Rogério Eiji; Pomella, Alan William V; Costa, Heron Salazar; Bezerra, José Luiz; Loguercio, Leandro L; Pereira, José O

2010-01-01

The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupuaçu) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupuaçu plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ∼70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies for biological control of black-pod rot of cacao. Copyright © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Preliminary in vitro insights into the use of natural fungal pathogens of leaf-cutting ants as biocontrol agents.

PubMed

Folgarait, Patricia; Gorosito, Norma; Poulsen, Michael; Currie, Cameron R

2011-09-01

Leaf-cutting ants are one of the main herbivores of the Neotropics, where they represent an important agricultural pest. These ants are particularly difficult to control because of the complex network of microbial symbionts. Leaf-cutting ants have traditionally been controlled through pesticide application, but there is a need for alternative, more environmentally friendly, control methods such as biological control. Potential promising biocontrol candidates include the microfungi Escovopsis spp. (anamorphic Hypocreales), which are specialized pathogens of the fungi the ants cultivate for food. These pathogens are suppressed through ant behaviors and ant-associated antibiotic-producing Actinobacteria. In order to be an effective biocontrol agent, Escovopsis has to overcome these defenses. Here, we evaluate, using microbial in vitro assays, whether defenses in the ant-cultivated fungus strain (Leucoagaricus sp.) and Actinobacteria from the ant pest Acromyrmex lundii have the potential to limit the use of Escovopsis in biocontrol. We also explore, for the first time, possible synergistic biocontrol between Escovopsis and the entomopathogenic fungus Lecanicillium lecanii. All strains of Escovopsis proved to overgrow A. lundii cultivar in less than 7 days, with the Escovopsis strain isolated from a different leaf-cutting ant species being the most efficient. Escovopsis challenged with a Streptomyces strain isolated from A. lundii did not exhibit significant growth inhibition. Both results are encouraging for the use of Escovopsis as a biocontrol agent. Although we found that L. lecanii can suppress the growth of the cultivar, it also had a negative impact on Escovopsis, making the success of simultaneous use of these two fungi for biocontrol of A. lundii questionable.

House fly (Musca domestica): a review of control strategies for a challenging pest.

PubMed

Malik, Anushree; Singh, Neena; Satya, Santosh

2007-05-01

Musca domestica L. (Diptera: Muscidae), commonly called the house fly, is a major domestic, medical and veterinary pest that causes irritation, spoils food and acts as a vector for many pathogenic organisms. In this paper, the social and health problems related to housefly are introduced with the associated need to control its population. Physical and chemical methods of house fly control are briefly discussed. The main focus of this review is on the biological control methods for house fly control, that comprise botanical, fungal, bacterial and parasitoid agents. Although several biocontrol agents are still in the nascent stage, some of them (especially fungal and parasitoid agents) have shown reliable field performance and seem to be suitable candidates for commercialization. However, the majority of these laboratory and field studies have been conducted in the temperate region. It remains to be seen whether the application of biocontrol agents would be feasible in tropical environments. The integrated pest management practices, which can provide more reliable field performance, have also been discussed. A multi-dimensional approach that exerts control on all the life stages of house fly, but simultaneously preserves the fly's natural enemies could be an ecologically sustainable way of maintaining the fly populations below maximally acceptable limits.

Impact of Biocontrol Pseudomonas fluorescens CHA0 and a Genetically Modified Derivative on the Diversity of Culturable Fungi in the Cucumber Rhizosphere

PubMed Central

Girlanda, M.; Perotto, S.; Moenne-Loccoz, Y.; Bergero, R.; Lazzari, A.; Defago, G.; Bonfante, P.; Luppi, A. M.

2001-01-01

Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day mark of either growth cycle was smaller than the effect of growing cucumber repeatedly in the same soil. PMID:11282643

Impact of biocontrol Pseudomonas fluorescens CHA0 and a genetically modified derivative on the diversity of culturable fungi in the cucumber rhizosphere.

PubMed

Girlanda, M; Perotto, S; Moenne-Loccoz, Y; Bergero, R; Lazzari, A; Defago, G; Bonfante, P; Luppi, A M

2001-04-01

Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day mark of either growth cycle was smaller than the effect of growing cucumber repeatedly in the same soil.

Bacillus amyloliquefaciens subsp. plantarum GR53, a potent biocontrol agent resists Rhizoctonia disease on Chinese cabbage through hormonal and antioxidants regulation.

PubMed

Kang, Sang-Mo; Radhakrishnan, Ramalingam; Lee, In-Jung

2015-10-01

The fungus Rhizoctonia solani is one of the causal agents of numerous diseases that affect crop growth and yield. The aim of this present investigation was to identify a biocontrol agent that acts against R. solani and to determine the agent's protective effect through phytohormones and antioxidant regulation in experimentally infected Chinese cabbage plants. Four rhizospheric soil bacterial isolates GR53, GR169, GR786, and GR320 were tested for their antagonistic activity against R. solani. Among these isolates, GR53 significantly suppressed fungal growth. GR53 was identified as Bacillus amyloliquefaciens subsp. plantarum by phylogenetic analysis of the 16S rDNA sequence. The biocontrol activity of B. amyloliquefaciens subsp. plantarum GR53 was tested in Chinese cabbage plants under controlled conditions. Results showed that R. solani inhibited plant growth (length, width, fresh and dry weight of leaves) by reducing chlorophyll and total phenolic content, as well as by increasing the levels of salicylic acid, jasmonic acid, abscisic acid, and DPPH scavenging activity. By regulating the levels of these compounds, the co-inoculation of B. amyloliquefaciens subsp. plantarum GR53 heightened induced systemic resistance in infected Chinese cabbage, effectively mitigating R. solani-induced damaging effects and improving plant growth. The results obtained from this study suggest that B. amyloliquefaciens subsp. plantarum GR53 is an effective biocontrol agent to prevent the damage caused by R. solani in Chinese cabbage plants.

Human exposure to airborne fungi from genera used as biocontrol agents in plant production.

PubMed

Madsen, Anne Mette; Hansen, Vinni Mona; Meyling, Nicolai Vitt; Eilenberg, Jørgen

2007-01-01

The fungi Trichoderma harzianum, T. polysporum, T. viride, Paeciliomyces fumosoroseus, P. lilacinus, Verticillium/lecanicillium lecanii, Ulocladium oudemansii, U. atrum and Beauveria bassiana are used or considered to be used for biocontrol of pests and plant diseases. Human exposure to these fungi in environments where they may naturally occur or are used as biocontrol agents has not been directly investigated to date. This review aims to provide an overview of the current knowledge of human exposure to fungi from the relevant genera. The subject of fungal taxonomy due to the rapid development of this issue is also discussed. B. bassiana, V. lecanii, T. harzianum, T. polysporum, P. lilacinus and U. oudemansii were infrequently present in the air and thus people in general seem to be seldom exposed to these fungi. However, when V. lecanii was present, high concentrations were measured. Fungi from the genera Trichoderma, Paecilomyces and Ulocladium were rarely identified to the species level and sometimes high concentrations were reported. T. viride and U. atrum were detected frequently in different environments and sometimes with a high frequency of presence in samples. Thus, people seem to be frequently exposed to these fungi. Sequence data have led to recent revisions of fungal taxonomy, and in future studies it is important to specify the taxonomy used for identification, thus making comparisons possible.

Isolation and characterization of Leu[7]-Surfactin from the endophytic bacterium Bacillus mojavensis RRC 101, a biocontrol agent for Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Bacillus mojavensis is an endophytic bacterium patented for control of fungal diseases in maize and other plants. Culture extracts and filtrates from this bacterium were antagonistic to the pathogenic and mycotoxic fungus Fusarium verticillioides. However, the identity of the inhibitory substance ...

Endophytic fungi harbored in the root of Sophora tonkinensis Gapnep: Diversity and biocontrol potential against phytopathogens.

PubMed

Yao, Yu Qun; Lan, Fang; Qiao, Yun Ming; Wei, Ji Guang; Huang, Rong Shao; Li, Liang Bo

2017-06-01

This work, for the first time, investigated the diversity of endophytic fungi harbored in the xylem and phloem of the root of Sophora tonkinensis Gapnep from three geographic localities with emphasis on the influence of the tissue type and geographic locality on endophytic fungal communities and their potential as biocontrol agents against phytopathogens of Panax notoginseng. A total of 655 fungal strains representing 47 taxa were isolated. Forty-two taxa (89.4%) were identified but not five taxa (10.6%) according to morphology and molecular phylogenetics. Out of identifiable taxa, the majority of endophyte taxa were Ascomycota (76.6%), followed by Basidiomycota (8.5%) and Zygomycota (4.3%). The alpha-diversity indices indicated that the species diversity of endophytic fungal community harbored in the root of S. tonkinensis was very high. The colonization and species diversity of endophytic fungal communities were significantly influenced by the geographic locality but not tissue type. The geographic locality and tissue type had great effects on the species composition of endophytic fungal communities. Forty-seven respective strains were challenged by three fungal phytopathogens of P. notoginseng and six strains exhibited significant inhibitory activity. It was noteworthy that endophytic Rhexocercosporidium sp. and F. solani strongly inhibited pathogenic F. solani and other fungal phytopathogens of P. notoginseng. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Biocontrol of Aspergillus Species on Peanut Kernels by Antifungal Diketopiperazine Producing Bacillus cereus Associated with Entomopathogenic Nematode

PubMed Central

Kumar, Sasidharan Nishanth; Sreekala, Sreerag Ravikumar; Chandrasekaran, Dileep; Nambisan, Bala; Anto, Ruby John

2014-01-01

The rhabditid entomopathogenic nematode associated Bacillus cereus and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by Aspergillus species in in vitro and in vivo tests. The results showed that B. cereus had a significant effect on biocontrol effectiveness in in vitro and in vivo conditions. The antifungal compounds produced by the B. cereus were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs) [cyclo-(L-Pro-Gly), cyclo(L-Tyr-L-Tyr), cyclo-(L-Phe-Gly) and cyclo(4-hydroxy-L-Pro-L-Trp)]. The antifungal activities of diketopiperazines were studied against five Aspergillus species and best MIC of 2 µg/ml was recorded against A. flavus by cyclo(4-hydroxy-L-Pro-L-Trp). To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp) to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of Aspergillus species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp). The cyclo(4-hydroxy-L-Pro-L-Trp) was nontoxic to two normal cell lines [fore skin (FS) normal fibroblast and African green monkey kidney (VERO)] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp) identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated B. cereus and cyclo(4-hydroxy-L-Pro-L-Trp) could be used as a biocontrol agents against postharvest fungal disease caused by Aspergillus species. PMID:25157831

Plant Growth Promoting and Biocontrol Activity of Streptomyces spp. as Endophytes.

PubMed

Vurukonda, Sai Shiva Krishna Prasad; Giovanardi, Davide; Stefani, Emilio

2018-03-22

There has been many recent studies on the use of microbial antagonists to control diseases incited by soilborne and airborne plant pathogenic bacteria and fungi, in an attempt to replace existing methods of chemical control and avoid extensive use of fungicides, which often lead to resistance in plant pathogens. In agriculture, plant growth-promoting and biocontrol microorganisms have emerged as safe alternatives to chemical pesticides. Streptomyces spp. and their metabolites may have great potential as excellent agents for controlling various fungal and bacterial phytopathogens. Streptomycetes belong to the rhizosoil microbial communities and are efficient colonizers of plant tissues, from roots to the aerial parts. They are active producers of antibiotics and volatile organic compounds, both in soil and in planta , and this feature is helpful for identifying active antagonists of plant pathogens and can be used in several cropping systems as biocontrol agents. Additionally, their ability to promote plant growth has been demonstrated in a number of crops, thus inspiring the wide application of streptomycetes as biofertilizers to increase plant productivity. The present review highlights Streptomyces spp.-mediated functional traits, such as enhancement of plant growth and biocontrol of phytopathogens.

Biocontrol of Sugarcane Smut Disease by Interference of Fungal Sexual Mating and Hyphal Growth Using a Bacterial Isolate.

PubMed

Liu, Shiyin; Lin, Nuoqiao; Chen, Yumei; Liang, Zhibin; Liao, Lisheng; Lv, Mingfa; Chen, Yufan; Tang, Yingxin; He, Fei; Chen, Shaohua; Zhou, Jianuan; Zhang, Lianhui

2017-01-01

Sugarcane smut is a fungal disease caused by Sporisorium scitamineum , which can cause severe economic losses in sugarcane industry. The infection depends on the mating of bipolar sporida to form a dikaryon and develops into hyphae to penetrate the meristematic tissue of sugarcane. In this study, we set to isolate bacterial strains capable of blocking the fungal mating and evaluate their potential in control of sugarcane smut disease. A bacterial isolate ST4 from rhizosphere displayed potent inhibitory activity against the mating of S. scitamineum bipolar sporida and was selected for further study. Phylogenetic analyses and biochemical characterization showed that the isolate was most similar to Pseudomonas guariconensis . Methanol extracts from minimum and potato dextrose agar (PDA) agar medium, on which strain ST4 has grown, showed strong inhibitory activity on the sexual mating of S. scitamineum sporida, without killing the haploid cells MAT-1 or MAT-2. Further analysis showed that only glucose, but not sucrose, maltose, and fructose, could support strain ST4 to produce antagonistic chemicals. Consistent with the above findings, greenhouse trials showed that addition of 2% glucose to the bacterial inoculum significantly increased the strain ST4 biocontrol efficiency against sugarcane smut disease by 77% than the inoculum without glucose. The results from this study depict a new strategy to screen for biocontrol agents for control and prevention of the sugarcane smut disease.

Tissue age and plant genotype affect the microbiota of apple and pear bark.

PubMed

Arrigoni, Elena; Antonielli, Livio; Pindo, Massimo; Pertot, Ilaria; Perazzolli, Michele

2018-06-01

Plant tissues host complex fungal and bacterial communities, and their composition is determined by host traits such as tissue age, plant genotype and environmental conditions. Despite the importance of bark as a possible reservoir of plant pathogenic microorganisms, little is known about the associated microbial communities. In this work, we evaluated the composition of fungal and bacterial communities in the pear (Abate and Williams cultivars) and apple (Golden Delicious and Gala cultivars) bark of three/four-year-old shoots (old bark) or one-year-old shoots (young bark), using a meta-barcoding approach. The results showed that both fungal and bacterial communities are dominated by genera with ubiquitous attitudes, such as Aureobasidium, Cryptococcus, Deinococcus and Hymenobacter, indicating intense microbial migration to surrounding environments. The shoot age, plant species and plant cultivar influenced the composition of bark fungal and bacterial communities. In particular, bark communities included potential biocontrol agents that could maintain an equilibrium with potential plant pathogens. The abundance of fungal (e.g. Alternaria, Penicillium, Rosellinia, Stemphylium and Taphrina) and bacterial (e.g. Curtobacterium and Pseudomonas) plant pathogens was affected by bark age and host genotype, as well as those of fungal genera (e.g. Arthrinium, Aureobasidium, Rhodotorula, Sporobolomyces) and bacterial genera (e.g. Bacillus, Brevibacillus, Methylobacterium, Sphingomonas and Stenotrophomonas) with possible biocontrol and plant growth promotion properties. Copyright © 2018 Elsevier GmbH. All rights reserved.

Evolutionarily informative strain-typing for Beauveria bassiana: multilocus haplotype stability and a genetic context for the mycoinsecticide GHA

USDA-ARS?s Scientific Manuscript database

Beauveria bassiana strain GHA (ARSEF3620, ATCC74250), the active component of mycoinsecticide formulations BotaniGard® and Mycotrol® (Certis, Columbia, MD), is a leading fungal biocontrol agent used against pest insects. Due to its pathogenicity and virulence toward diverse insect taxa, GHA is often...

Study on Interactions between the Major Apple Valsa Canker Pathogen Valsa mali and Its Biocontrol Agent Saccharothrix yanglingensis Hhs.015 Using RT-qPCR

PubMed Central

Fan, Dongying; Li, Yanfang; Zhao, Lingyun; Li, Zhengpeng; Huang, Lili; Yan, Xia

2016-01-01

The mechanism of biocontrol agent Saccharothrix yanglingensis Hhs.015 action against Valsa mali, a major apple Valsa canker pathogen, was examined using a novel, sensitive (minimum detection limit 100 pg/μL) and reliably RT-qPCR technique. Prior to lesion formation, total concentration of V. mali in the bark showed a significant decrease (p<0.05) after 24 h of Hhs.015 treatment. This was more pronounced at 48 and 96 h post treatment. After lesion formation, levels of V. mali remained constant at the boundary between infected and uninfected bark tissues, although the relative expansion rate of the lesion was significantly reduced (p<0.05). Gene expression levels of endo-polygalacturonase, a marker for fungal pathogenicity, were sharply reduced while host induced resistance callose synthase levels increased significantly (p<0.05) at the boundary bark at 9 d after Hhs.015 treatment. The results showed that biocontrol agent Hhs.015 prevented infection of V. mali by inhibiting pathogen growth, down-regulating pathogenicity factor expression and inducing a high level of host resistance. PMID:27611855

Isolation of fungi from dead arthropods and identification of a new mosquito natural pathogen.

PubMed

Jaber, Sana; Mercier, Alex; Knio, Khouzama; Brun, Sylvain; Kambris, Zakaria

2016-09-05

Insects are well known vectors of human and animal pathogens and millions of people are killed by mosquito-borne diseases every year. The use of insecticides to target insect vectors has been hampered by the issues of toxicity to the environment and by the selection of resistant insects. Therefore, biocontrol strategies based on naturally occurring microbial pathogens emerged as a promising control alternative. The entomopathogenic fungus Beauveria bassiana is well characterized and have been approved by the United States Environmental Protection Agency as a pest biological control method. However, thousands of other fungi are unexploited and it is important to identify and use different fungi for biocontrol with possibly some vector specific strains. The aim of this study was to identify new fungal entomopathogens that may be used as potential mosquito biocontrol agents. Cadavers of arthropods were collected from pesticide free areas and the fungi associated isolated, cultured and identified. Then the ability of each isolate to kill laboratory insects was assayed and compared to that of B. bassiana. In total we have isolated and identified 42 fungal strains from 17 different arthropod cadavers. Twenty four fungal isolates were cultivated in the laboratory and were able to induce sporulation. When fungal spores were microinjected into Drosophila melanogaster, eight isolates proved to be highly pathogenic while the remaining strains showed moderate or no pathogenicity. Then a selection of isolates was tested against Aedes mosquitoes in a model mimicking natural infections. Only one fungus (Aspergillus nomius) was as pathogenic as B. bassiana and able to kill 100 % of the mosquitoes. The obtained results are encouraging and demonstrate the feasibility of this simple approach for the identification of new potential mosquito killers. Indeed, it is essential to anticipate and prepare biocontrol methods to fight the expansion of mosquitoes' habitat predicted in certain geographical areas in association with the occurring climatic changes.

Bioprospecting endophytic diazotrophic Lysinibacillus sphaericus as biocontrol agents of rice sheath blight disease.

PubMed

Shabanamol, S; Sreekumar, J; Jisha, M S

2017-10-01

The present study tried to explore the possible in vitro biocontrol mechanisms of Lysinibacillus sphaericus , a diazotrophic endophyte from rice against the rice sheath blight pathogen Rhizoctonia solani. The in vivo biocontrol potential of the isolate and the induction of systemic resistance under greenhouse conditions have also been experimented employing different treatments with positive control carbendazim, the chemical fungicide. The endophytic isolate showed 100% growth inhibition of the fungal pathogen via volatile organic compound production and was positive for the production of siderophores, biosurfactants, HCN, and ammonia. Under greenhouse conditions, foliar and soil application of L. sphaericus significantly decreased the percentage of disease incidence. All bacterized treatments are superior to chemical fungicide treatment. Application of L. sphaericus in single and combination treatments induces systemic resistance as evident from the significant accumulation of defense enzymes such as peroxides, polyphenol oxides and phenylalanine ammonia in addition to the increase of phenolic compounds. The results biologically prospect endophytic diazotroph L. sphaericus as a potent plant growth promoter with excellent biocontrol efficiency.

Proliferation of the biocontrol agent Fusarium oxysporum f. sp. strigae and its impact on indigenous rhizosphere fungal communities in maize under different agro-ecologies.

PubMed

Zimmermann, Judith; Musyoki, Mary K; Cadisch, Georg; Rasche, Frank

2016-06-01

Our objectives were to (1) monitor the proliferation of the biocontrol agent (BCA) Fusarium oxysporum f. sp. strigae strain "Foxy-2", an effective soil-borne BCA against the parasitic weed Striga hermonthica , in the rhizosphere of maize under different agro-ecologies, and (2) investigate its impact on indigenous rhizosphere fungal community abundance and composition. Field experiments were conducted in Busia and Homa Bay districts in western Kenya during two cropping seasons to account for effects of soil type, climate, growth stage and seasonality. Maize seeds were coated with or without "Foxy-2" and soils were artificially infested with S. hermonthica seeds. One treatment with nitrogen rich organic residues ( Tithonia diversifolia ) was established to compensate hypothesized resource competition between "Foxy-2" and the indigenous fungal community. Rhizosphere soil samples collected at three growth stages (i.e., EC30, EC60, EC90) of maize were subjected to abundance measurement of "Foxy-2" and total indigenous fungi using quantitative polymerase chain reaction (qPCR) analysis. Terminal restriction fragment length polymorphism (TRFLP) analysis was used to assess potential alterations in the fungal community composition in response to "Foxy-2" presence. "Foxy-2" proliferated stronger in the soils with a sandy clay texture (Busia) than in those with a loamy sand texture (Homa Bay) and revealed slightly higher abundance in the second season. "Foxy-2" had, however, only a transient suppressive effect on total indigenous fungal abundance which ceased in the second season and was further markedly compensated after addition of T. diversifolia residues. Likewise, community structure of the indigenous fungal community was mainly altered by maize growth stages, but not by "Foxy-2". In conclusion, no adverse effects of "Foxy-2" inoculation on indigenous fungal rhizosphere communities were observed corroborating the safety of this BCA under the given agro-ecologies.

JGI Fungal Genomics Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor V.

2011-03-14

Genomes of energy and environment fungi are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). Its key project, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts), and explores fungal diversity by means of genome sequencing and analysis. Over 50 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supported by functionalmore » genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such 'parts' suggested by comparative genomics and functional analysis in these areas are presented here« less

The Transition from a Phytopathogenic Smut Ancestor to an Anamorphic Biocontrol Agent Deciphered by Comparative Whole-Genome Analysis[W][OPEN

PubMed Central

Lefebvre, François; Joly, David L.; Labbé, Caroline; Teichmann, Beate; Linning, Rob; Belzile, François; Bakkeren, Guus; Bélanger, Richard R.

2013-01-01

Pseudozyma flocculosa is related to the model plant pathogen Ustilago maydis yet is not a phytopathogen but rather a biocontrol agent of powdery mildews; this relationship makes it unique for the study of the evolution of plant pathogenicity factors. The P. flocculosa genome of ∼23 Mb includes 6877 predicted protein coding genes. Genome features, including hallmarks of pathogenicity, are very similar in P. flocculosa and U. maydis, Sporisorium reilianum, and Ustilago hordei. Furthermore, P. flocculosa, a strict anamorph, revealed conserved and seemingly intact mating-type and meiosis loci typical of Ustilaginales. By contrast, we observed the loss of a specific subset of candidate secreted effector proteins reported to influence virulence in U. maydis as the singular divergence that could explain its nonpathogenic nature. These results suggest that P. flocculosa could have once been a virulent smut fungus that lost the specific effectors necessary for host compatibility. Interestingly, the biocontrol agent appears to have acquired genes encoding secreted proteins not found in the compared Ustilaginales, including necrosis-inducing-Phytophthora-protein- and Lysin-motif- containing proteins believed to have direct relevance to its lifestyle. The genome sequence should contribute to new insights into the subtle genetic differences that can lead to drastic changes in fungal pathogen lifestyles. PMID:23800965

Native Killer Yeasts as Biocontrol Agents of Postharvest Fungal Diseases in Lemons.

PubMed

Perez, María Florencia; Contreras, Luciana; Garnica, Nydia Mercedes; Fernández-Zenoff, María Verónica; Farías, María Eugenia; Sepulveda, Milena; Ramallo, Jacqueline; Dib, Julián Rafael

2016-01-01

Economic losses caused by postharvest diseases represent one of the main problems of the citrus industry worldwide. The major diseases affecting citrus are the "green mold" and "blue mold", caused by Penicillium digitatum and P. italicum, respectively. To control them, synthetic fungicides are the most commonly used method. However, often the emergence of resistant strains occurs and their use is becoming more restricted because of toxic effects and environmental pollution they generate, combined with trade barriers to international markets. The aim of this work was to isolate indigenous killer yeasts with antagonistic activity against fungal postharvest diseases in lemons, and to determine their control efficiency in in vitro and in vivo assays. Among 437 yeast isolates, 8.5% show to have a killer phenotype. According to molecular identification, based on the 26S rDNA D1/D2 domain sequences analysis, strains were identified belonging to the genera Saccharomyces, Wickerhamomyces, Kazachstania, Pichia, Candida and Clavispora. Killers were challenged with pathogenic molds and strains that caused the maximum in vitro inhibition of P. digitatum were selected for in vivo assays. Two strains of Pichia and one strain of Wickerhamomyces depicted a significant protection (p <0.05) from decay by P. digitatum in assays using wounded lemons. Thus, the native killer yeasts studied in this work showed to be an effective alternative for the biocontrol of postharvest fungal infections of lemons and could be promising agents for the development of commercial products for the biological control industry.

Native Killer Yeasts as Biocontrol Agents of Postharvest Fungal Diseases in Lemons

PubMed Central

Garnica, Nydia Mercedes; Fernández-Zenoff, María Verónica; Farías, María Eugenia; Sepulveda, Milena; Ramallo, Jacqueline; Dib, Julián Rafael

2016-01-01

Economic losses caused by postharvest diseases represent one of the main problems of the citrus industry worldwide. The major diseases affecting citrus are the "green mold" and "blue mold", caused by Penicillium digitatum and P. italicum, respectively. To control them, synthetic fungicides are the most commonly used method. However, often the emergence of resistant strains occurs and their use is becoming more restricted because of toxic effects and environmental pollution they generate, combined with trade barriers to international markets. The aim of this work was to isolate indigenous killer yeasts with antagonistic activity against fungal postharvest diseases in lemons, and to determine their control efficiency in in vitro and in vivo assays. Among 437 yeast isolates, 8.5% show to have a killer phenotype. According to molecular identification, based on the 26S rDNA D1/D2 domain sequences analysis, strains were identified belonging to the genera Saccharomyces, Wickerhamomyces, Kazachstania, Pichia, Candida and Clavispora. Killers were challenged with pathogenic molds and strains that caused the maximum in vitro inhibition of P. digitatum were selected for in vivo assays. Two strains of Pichia and one strain of Wickerhamomyces depicted a significant protection (p <0.05) from decay by P. digitatum in assays using wounded lemons. Thus, the native killer yeasts studied in this work showed to be an effective alternative for the biocontrol of postharvest fungal infections of lemons and could be promising agents for the development of commercial products for the biological control industry. PMID:27792761

Development of a population-based threshold model of conidial germination for analysing the effects of physiological manipulation on the stress tolerance and infectivity of insect pathogenic fungi.

PubMed

Andersen, M; Magan, N; Mead, A; Chandler, D

2006-09-01

Entomopathogenic fungi are being used as biocontrol agents of insect pests, but their efficacy can be poor in environments where water availability is reduced. In this study, the potential to improve biocontrol by physiologically manipulating fungal inoculum was investigated. Cultures of Beauveria bassiana, Lecanicillium muscarium, Lecanicillium longisporum, Metarhizium anisopliae and Paecilomyces fumosoroseus were manipulated by growing them under conditions of water stress, which produced conidia with increased concentrations of erythritol. The time-course of germination of conidia at different water activities (water activity, aw) was described using a generalized linear model, and in most cases reducing the water activity of the germination medium delayed the onset of germination without affecting the distribution of germination times. The germination of M. anisopliae, L. muscarium, L. longisporum and P. fumosoroseus was accelerated over a range of aw levels as a result of physiological manipulation. However, the relationship between the effect of physiological manipulation on germination and the osmolyte content of conidia varied according to fungal species. There was a linear relationship between germination rate, expressed as the reciprocal of germination time, and aw of the germination medium, but there was no significant effect of fungal species or physiological manipulation on the aw threshold for germination. In bioassays with M. anisopliae, physiologically manipulated conidia germinated more rapidly on the surface of an insect host, the melon cotton aphid Aphis gossypii, and fungal virulence was increased even when relative humidity was reduced after an initial high period. It is concluded that physiological manipulation may lead to improvements in biocontrol in the field, but choice of fungal species/isolate will be critical. In addition, the population-based threshold model used in this study, which considered germination in terms of physiological time, also called hydrotime, could have general application in mycology and environmental microbiology.

Yeast Biocontrol of a Fungal Plant Disease: A Model for Studying Organism Interrelationships

ERIC Educational Resources Information Center

Chanchaichaovivat, Arun; Panijpan, Bhinyo; Ruenwongsa, Pintip

2008-01-01

An experiment on the action of the yeast, "Saccharomyces cerevisiae", against a fungal plant disease is proposed for secondary students (Grade 11) to support their study of organism interrelationship. This biocontrol experiment serves as the basis for discussing relationships among three organisms (red chilli fruit, "Saccharomyces cerevisiae," and…

Biocontrol ability and putative mode of action of yeasts against Geotrichum citri-aurantii in citrus fruit.

PubMed

Ferraz, Luriany Pompeo; Cunha, Tatiane da; da Silva, Aline Caroline; Kupper, Katia Cristina

2016-01-01

Sour rot is a major postharvest disease of citrus fruit and is caused by the fungal pathogen Geotrichum citri-aurantii. A lack of chemicals certified for the control of this disease has led to the consideration of alternative methods and strategies, such as the use of yeasts as biocontrol agents. The purpose of the present study was to test the ability of yeasts isolated from leaves, flowers, fruit, and soil, and six Saccharomyces cerevisiae isolates to control citrus sour rot, to assess the mechanisms of action of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of G. citri-aurantii. In in vivo assays, three yeast isolates (ACBL-23, ACBL-44, and ACBL-77) showed a potential for controlling sour rot in citrus fruits, both preventatively and curatively. Most of the eight yeast isolates that were assessed for a mechanism of action did not produce antifungal compounds in an amount sufficient to inhibit the growth of the pathogen. Additionally, nutrient competition among the yeast strains was not found to be a biocontrol strategy. Instead, killer activity and hydrolytic enzyme production were identified as the major mechanisms involved in the biocontrol activity of the yeasts. Isolates ACBL-23, ACBL-44, and ACBL-77, which controlled sour rot most effectively, were identified as Rhodotorula minuta, Candida azyma, and Aureobasidium pullulans, respectively. To our knowledge, this is the first report of the potential of C. azyma as a biological control agent against a postharvest pathogen and its ability to produce a killer toxin. Copyright © 2016 Elsevier GmbH. All rights reserved.

Alternative strawberry disease management strategy: combing low UV-C irradiation in dark, disabling pathogen’s UV-C repair mechanism, and preventing pathogen establishment with biocontrol agents

USDA-ARS?s Scientific Manuscript database

The limitations of current fungicides necessitate a search for new approaches. Low-dose or sub-lethal UV-C irradiation (12.36 J/m2) alone is not effective in controlling fungal diseases, especially when the plants are exposed to UV-C irradiation during the day. We found, however, that application ...

Selection and evaluation of micro-organisms for biocontrol of Verticillium dahliae in olive.

PubMed

Varo, A; Raya-Ortega, M C; Trapero, A

2016-09-01

To identify potential biological control agents against Verticillium wilt in olive through a mass screening approach. A total of 47 strains and nine mixtures of micro-organisms were evaluated against Verticillium dahliae in a three stage screening: (i) in vitro, by the effect on the mycelial growth and spore germination of the pathogen; (ii) in natural infested soil, by the effect on the reduction of microsclerotia of the pathogen; (iii) in planta, by the effect on the infection of olive plants under controlled conditions. Various fungal and bacterial strains and mixtures inhibited the pathogen and showed consistent biocontrol activity against Verticillium wilt of olive. The screening has resulted in promising fungi and bacteria strains with antagonistic activity against Verticillium, such as two non-pathogenic Fusarium oxysporum, one Phoma sp., one Pseudomonas fluorescens and two mixtures of micro-organisms that may possess multiple modes of action. This study provides a practical basis for the potential use of selected strains as biocontrol agents for the protection of olive plants against V. dahliae infection. In addition, our study presented an effective method to evaluate antagonistic micro-organisms of V. dahliae in olive. © 2016 The Society for Applied Microbiology.

Effect of nutrition and environmental factors on the endoparasitic fungus Esteya vermicola, a biocontrol agent against pine wilt disease.

PubMed

Xue, Jianjie; Zhang, Yongan; Wang, Chunyan; Wang, Yuzhu; Hou, Jingang; Wang, Zhen; Wang, Yunbo; Gu, Lijuan; Sung, Changkeun

2013-09-01

The nematophagous fungus Esteya vermicola has tremendous potential for biological control. This species exhibits strong infectious activity against pinewood nematodes, whereas the study on the effect of nutrition and environmental factors is still of paucity. Carbon (C), nitrogen (N), pH value, temperature, and water activity have great impact on the fungal growth, sporulation, and germination. In nutrition study, the greatest number of conidia (2.36 × 10(9) per colony) was obtained at the C:N ratio of 100:1 with a carbon concentration 32 g l(-1). In addition, the germination rate and radial growth of E. vermicola were used to evaluate the effects of environmental conditions and they were optimized as following: pH 5.5, 26 °C and water activity of 0.98. Our results also confirmed that variation of environmental factors has a detrimental influence on the efficacy of active conidia and growth of fungus. Moreover, under above optimal condition, the biocontrol efficacy was significantly improved in regard to the increase of adhesive and mortality rate, which highlight the study on the application of E. vermicola as pine wilt disease biocontrol agent.

Ecological activity for mycotoxin beyond toxicity: screening mycotoxins for quorum inhibition

USDA-ARS?s Scientific Manuscript database

ABSTRACT: Biocontrol organisms are becoming essential features of several agricultural based crops, and bacterial endophytes are important components of several biocontrol systems. We are developing bacterial endophytes for use as biocontrol organisms for the corn fungal endophyte Fusarium verticil...

The effect of entomopathogenic fungal culture filtrate on the immune response of the greater wax moth, Galleria mellonella.

PubMed

Mc Namara, Louise; Carolan, James C; Griffin, Christine T; Fitzpatrick, David; Kavanagh, Kevin

2017-07-01

Galleria mellonella is a well-established model species regularly employed in the study of the insect immune response at cellular and humoral levels to investigate fungal pathogenesis and biocontrol agents. A cellular and proteomic analysis of the effect of culture filtrate of three entomopathogenic fungi (EPF) species on the immune system of G. mellonella was performed. Treatment with Beauveria caledonica and Metarhizium anisopliae 96h culture filtrate facilitated a significantly increased yeast cell density in larvae (3-fold and 3.8-fold, respectively). Larvae co-injected with either M. anisopliae or B. caledonica culture filtrate and Candida albicans showed significantly increased mortality. The same was not seen for larvae injected with Beauveria bassiana filtrate. Together these results suggest that B. caledonica and M. anisopliae filtrate are modulating the insect immune system allowing a subsequent pathogen to proliferate. B. caledonica and M. anisopliae culture filtrates impact upon the larval prophenoloxidase (ProPO) cascade (e.g. ProPO activating factor 3 and proPO activating enzyme 3 were increased in abundance relative to controls), while B. bassiana treated larvae displayed higher abundances of alpha-esterase when compared to control larvae (2.4-fold greater) and larvae treated with M. anisopliae and B. caledonica. Treatment with EPF culture filtrate had a significant effect on antimicrobial peptide abundances particularly in M. anisopliae treated larvae where cecropin-D precursor, hemolin and gloverin were differentially abundant in comparison to controls. Differences in proteomic profiles for different treatments may reflect or even partially explain the differences in their immunomodulatory potential. Screening EPF for their ability to modulate the insect immune response represents a means of assessing EPF for use as biocontrol agents, particularly if the goal is to use them in combination with other control agents. Additionally EPF represent a valuable resource pool in our search for natural products with insect immunomodulatory and biocontrol properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere.

PubMed

Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

2016-04-01

Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

Identification of growth stage molecular markers in Trichoderma sp. 'atroviride type B' and their potential application in monitoring fungal growth and development in soil.

PubMed

Mendoza-Mendoza, Artemio; Steyaert, Johanna; Nieto-Jacobo, Maria Fernanda; Holyoake, Andrew; Braithwaite, Mark; Stewart, Alison

2015-11-01

Several members of the genus Trichoderma are biocontrol agents of soil-borne fungal plant pathogens. The effectiveness of biocontrol agents depends heavily on how they perform in the complex field environment. Therefore, the ability to monitor and track Trichoderma within the environment is essential to understanding biocontrol efficacy. The objectives of this work were to: (a) identify key genes involved in Trichoderma sp. 'atroviride type B' morphogenesis; (b) develop a robust RNA isolation method from soil; and (c) develop molecular marker assays for characterizing morphogenesis whilst in the soil environment. Four cDNA libraries corresponding to conidia, germination, vegetative growth and conidiogenesis were created, and the genes identified by sequencing. Stage specificity of the different genes was confirmed by either Northern blot or quantitative reverse-transcriptase PCR (qRT-PCR) analysis using RNA from the four stages. con10, a conidial-specific gene, was observed in conidia, as well as one gene also involved in subsequent stages of germination (L-lactate/malate dehydrogenase encoding gene). The germination stage revealed high expression rates of genes involved in amino acid and protein biosynthesis, while in the vegetative-growth stage, genes involved in differentiation, including the mitogen-activated protein kinase kinase similar to Kpp7 from Ustilago maydis and the orthologue to stuA from Aspergillus nidulans, were preferentially expressed. Genes involved in cell-wall synthesis were expressed during conidiogenesis. We standardized total RNA isolation from Trichoderma sp. 'atroviride type B' growing in soil and then examined the expression profiles of selected genes using qRT-PCR. The results suggested that the relative expression patterns were cyclic and not accumulative.

Fungal Genomics Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor

The JGI Fungal Genomics Program aims to scale up sequencing and analysis of fungal genomes to explore the diversity of fungi important for energy and the environment, and to promote functional studies on a system level. Combining new sequencing technologies and comparative genomics tools, JGI is now leading the world in fungal genome sequencing and analysis. Over 120 sequenced fungal genomes with analytical tools are available via MycoCosm (www.jgi.doe.gov/fungi), a web-portal for fungal biologists. Our model of interacting with user communities, unique among other sequencing centers, helps organize these communities, improves genome annotation and analysis work, and facilitates new larger-scalemore » genomic projects. This resulted in 20 high-profile papers published in 2011 alone and contributing to the Genomics Encyclopedia of Fungi, which targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts). Our next grand challenges include larger scale exploration of fungal diversity (1000 fungal genomes), developing molecular tools for DOE-relevant model organisms, and analysis of complex systems and metagenomes.« less

Genomic Encyclopedia of Fungi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor

Genomes of fungi relevant to energy and environment are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). Its key project, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts), and explores fungal diversity by means of genome sequencing and analysis. Over 150 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supportedmore » by functional genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such parts suggested by comparative genomics and functional analysis in these areas are presented here.« less

Potential of genes and gene products from Trichoderma sp. and Gliocladium sp. for the development of biological pesticides.

PubMed

Lorito, M; Hayes, C K; Zoina, A; Scala, F; Del Sorbo, G; Woo, S L; Harman, G E

1994-12-01

Fungal cell wall degrading enzymes produced by the biocontrol fungi Trichoderma harzianum and Gliocladium virens are strong inhibitors of spore germination and hyphal elongation of a number of phytopathogenic fungi. The purified enzymes include chitinolytic enzymes with different modes of action or different substrate specificity and glucanolytic enzymes with exo-activity. A variety of synergistic interactions were found when different enzymes were combined or associated with biotic or abiotic antifungal agents. The levels of inhibition obtained by using enzyme combinations were, in some cases, comparable with commercial fungicides. Moreover, the antifungal interaction between enzymes and common fungicides allowed the reduction of the chemical doses up to 200-fold. Chitinolytic and glucanolytic enzymes from T. harzianum were able to improve substantially the antifungal ability of a biocontrol strain of Enterobacter cloacae. DNA fragments containing genes encoding for different chitinolytic enzymes were isolated from a cDNA library of T. harzianum and cloned for mechanistic studies and biocontrol purposes. Our results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of lytic enzymes and their genes for biological control of plant diseases.

Fungal Endophytes: Beyond Herbivore Management

PubMed Central

Bamisile, Bamisope S.; Dash, Chandra K.; Akutse, Komivi S.; Keppanan, Ravindran; Wang, Liande

2018-01-01

The incorporation of entomopathogenic fungi as biocontrol agents into Integrated Pest Management (IPM) programs without doubt, has been highly effective. The ability of these fungal pathogens such as Beauveria bassiana and Metarhizium anisopliae to exist as endophytes in plants and protect their colonized host plants against the primary herbivore pests has widely been reported. Aside this sole role of pest management that has been traditionally ascribed to fungal endophytes, recent findings provided evidence of other possible functions as plant yield promoter, soil nutrient distributor, abiotic stress and drought tolerance enhancer in plants. However, reports on these additional important effects of fungal endophytes on the colonized plants remain scanty. In this review, we discussed the various beneficial effects of endophytic fungi on the host plants and their primary herbivore pests; as well as some negative effects that are relatively unknown. We also highlighted the prospects of our findings in further increasing the acceptance of fungal endophytes as an integral part of pest management programs for optimized crop production. PMID:29628919

Medium components and culture conditions affect the thermotolerance of aerial conidia of fungal biocontrol agent Beauveria bassiana.

PubMed

Ying, S-H; Feng, M-G

2006-09-01

To produce more thermotolerable conidia of Beauveria bassiana, a well-known fungal biocontrol agent, by optimizing the medium components and culture conditions. The conidia produced on media including 0.5-6% glucose, sucrose or starch as carbon source and 50-300-microg ml(-1) Cu2+, Zn2+, Mn2+ or Fe3+ as additive to Sabouraud dextrose medium at 15-30 degrees C, pH 4-8 or KCl-adjusted water availabilities were exposed to 30-min wet heat stress at 48 degrees C. The medium components for conidial production with greatly enhanced thermotolerance included 4% glucose as optimum or 1% starch as alternative for the carbon source and < or =50-microg ml(-1) Mn2+ for the metal additive. The culture conditions were optimized as 25 degrees C and pH 5-6. Conidial thermotolerance decreased remarkably when sucrose and Fe3+ or Cu2+ were used in the cultures, but altered slightly when 50-200-microg ml(-1) Zn2+ were included. The tolerance of B. bassiana conidia to the thermal stress was significantly affected by the medium composition and culture conditions under which the conidia were produced. Proper treatment of small grains as mass production substrates for more glucose release and supplement of glucose or 50-microg ml(-1) Mn2+ are possible means to enhancing conidial thermotolerance and field persistence for improved insect control.

Biocontrol agents promote growth of potato pathogens, depending on environmental conditions.

PubMed

Cray, Jonathan A; Connor, Mairéad C; Stevenson, Andrew; Houghton, Jonathan D R; Rangel, Drauzio E N; Cooke, Louise R; Hallsworth, John E

2016-05-01

There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused on interactions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth = 0.928) to out-perform Phytophthora infestans (~0.960) and challenge Fusarium coeruleum (~0.847) and Fusarium sambucinum (~0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Biocontrol activity of surfactin A purified from Bacillus NH-100 and NH-217 against rice bakanae disease.

PubMed

Sarwar, Ambrin; Hassan, Muhammad Nadeem; Imran, Muhammad; Iqbal, Mazhar; Majeed, Saima; Brader, Günter; Sessitsch, Angela; Hafeez, Fauzia Yusuf

2018-04-01

The potential of the Bacillus genus to antagonize phytopathogens is associated with the production of cyclic lipopeptides. Depending upon the type of lipopeptide, they may serve as biocontrol agents that are eco-friendly alternatives to chemical fertilizers. This study evaluates the biocontrol activity of surfactin-producing Bacillus (SPB) strains NH-100 and NH-217 and purified surfactin A from these strains against rice bakanae disease. Biologically active surfactin fractions were purified by HPLC, and surfactin A variants with chain lengths from C12 to C16 were confirmed by LCMS-ESI. In hemolytic assays, a positive correlation between surfactin A production and halo zone formation was observed. The purified surfactin A had strong antifungal activity against Fusarium oxysporum, F. moniliforme, F. solani, Trichoderma atroviride and T. reesei. Maximum fungal growth suppression (84%) was recorded at 2000 ppm against F. moniliforme. Surfactin A retained antifungal activity at different pH levels (5-9) and temperatures (20, 50 and 121 °C). Hydroponic and pot experiments were conducted to determine the biocontrol activity of SPB strains and the purified surfactin A from these strains on Super Basmati rice. Surfactin production in the rice rhizosphere was detected by LCMS-ESI at early growth stages in hydroponics experiments inoculated with SPB strains. However, the maximum yield was observed with a consortium of SPB strains (T4) and purified surfactin A (T5) treatments in the pot experiment. The outcomes of the present study revealed that surfactin A significantly reduced rice bakanae disease by up to 80%. These findings suggest that purified surfactin A could be an effective biocontrol agent against bakanae disease in rice and should be incorporated into strategies for disease management. Copyright © 2018 Elsevier GmbH. All rights reserved.

Mycobiome of Cysts of the Soybean Cyst Nematode Under Long Term Crop Rotation.

PubMed

Hu, Weiming; Strom, Noah; Haarith, Deepak; Chen, Senyu; Bushley, Kathryn E

2018-01-01

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe (Phylum Nematoda), is a major pathogen of soybean. It causes substantial yield losses worldwide and is difficult to control because the cyst protects the eggs which can remain viable for nearly a decade. Crop rotation with non-host crops and use of biocontrol organisms such as fungi and bacteria offer promising approaches, but remain hampered by lack of knowledge of the biology of nematode parasitic organisms. We used a high-throughput metabarcoding approach to characterize fungal communities associated with the SCN cyst, a microenvironment in soil that may harbor both nematode parasites and plant pathogens. SCN cysts were collected from a long-term crop rotation experiment in Southeastern Minnesota at three time points over two growing seasons to characterize diversity of fungi inhabiting cysts and to examine how crop rotation and seasonal variation affects fungal communities. A majority of fungi in cysts belonged to Ascomycota and Basidiomycota, but the presence of several early diverging fungal subphyla thought to be primarily plant and litter associated, including Mortierellomycotina and Glomeromycotina (e.g., arbuscular mycorrhizal fungi), suggests a possible role as nematode egg parasites. Species richness varied by both crop rotation and season and was higher in early years of crop rotation and in fall at the end of the growing season. Crop rotation and season also impacted fungal community composition and identified several classes of fungi, including Eurotiomycetes, Sordariomycetes, and Orbiliomycetes (e.g., nematode trapping fungi), with higher relative abundance in early soybean rotations. The relative abundance of several genera was correlated with increasing years of soybean. Fungal communities also varied by season and were most divergent at midseason. The percentage of OTUs assigned to Mortierellomycotina_cls_Incertae_sedis and Sordariomycetes increased at midseason, while Orbiliomycetes decreased at midseason, and Glomeromycetes increased in fall. Ecological guilds of fungi containing an animal-pathogen lifestyle, as well as potential egg-parasitic taxa previously isolated from parasitized SCN eggs, increased at midseason. The animal pathogen guilds included known (e.g., Pochonia chlamydosporia ) and new candidate biocontrol organisms. This research advances knowledge of the ecology of nematophagous fungi in agroecosystems and their use as biocontrol agents of the SCN.

Response of Vitis vinifera cell cultures to Eutypa lata and Trichoderma atroviride culture filtrates: expression of defence-related genes and phenotypes.

PubMed

Mutawila, C; Stander, C; Halleen, F; Vivier, M A; Mostert, L

2017-03-01

Cell suspension cultures of Vitis vinifera cv. Dauphine berries were used to study the response to the vascular pathogen, Eutypa lata, in comparison with a biological control agent, Trichoderma atroviride, that was previously shown to be effective in pruning wound protection. The expression of genes coding for enzymes of the phenylpropanoid pathway and pathogenesis-related (PR) proteins was profiled over a 48-h period using quantitative reverse transcriptase PCR. The cell cultures responded to elicitors of both fungi with a hypersensitive-like response that lead to a decrease in cell viability. Similar genes were triggered by both the pathogen and biocontrol agent, but the timing patterns and magnitude of expression was dependent on the specific fungal elicitor. Culture filtrates of both fungi caused upregulation of phenylalanine ammonia-lyase (PAL), 4-coumaroyl Co-A ligase (CCo-A) and stilbene synthase (STS), and a downregulation of chalcone synthase (CHS) genes. The pathogen filtrate caused a biphasic pattern in the upregulation of PAL and STS genes which was not observed in cells treated with filtrates of the biocontrol agent. Analytical assays showed significantly higher total phenolic content and chitinolytic enzyme activity in the cell cultures treated with the T. atroviride filtrate compared to the pathogen filtrate. These results corresponded well to the higher expression of PAL and chitinase class IV genes. The response of the cell cultures to T. atroviride filtrate provides support for the notion that the wound protection by the biocontrol agent at least partially relies on the induction of grapevine resistance mechanisms.

Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers.

PubMed

Nzioki, Henry S; Oyosi, Florence; Morris, Cindy E; Kaya, Eylul; Pilgeram, Alice L; Baker, Claire S; Sands, David C

2016-01-01

Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize. This overall strategy resulted in an average of >50% increased maize yield in the March to June rains season and >40% in the September to December rains season. Integration of this enhanced plant pathogen to Striga management in maize can significantly increase the maize yield of smallholder farmers in Kenya.

Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers

PubMed Central

Nzioki, Henry S.; Oyosi, Florence; Morris, Cindy E.; Kaya, Eylul; Pilgeram, Alice L.; Baker, Claire S.; Sands, David C.

2016-01-01

Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize. This overall strategy resulted in an average of >50% increased maize yield in the March to June rains season and >40% in the September to December rains season. Integration of this enhanced plant pathogen to Striga management in maize can significantly increase the maize yield of smallholder farmers in Kenya. PMID:27551284

Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt.

PubMed

Deketelaere, Silke; Tyvaert, Lien; França, Soraya C; Höfte, Monica

2017-01-01

The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae , and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta . Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be considered early in the process of selecting BCAs against Verticillium .

Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt

PubMed Central

Deketelaere, Silke; Tyvaert, Lien; França, Soraya C.; Höfte, Monica

2017-01-01

The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae, and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta. Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be considered early in the process of selecting BCAs against Verticillium. PMID:28729855

Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

PubMed

Singh, Udai B; Malviya, Deepti; Wasiullah; Singh, Shailendra; Pradhan, Jatindra K; Singh, Bhanu P; Roy, Manish; Imram, Mohd; Pathak, Neelam; Baisyal, B M; Rai, Jai P; Sarma, B K; Singh, Rajiv K; Sharma, P K; Kaur, Saman Deep; Manna, M C; Sharma, Sushil K; Sharma, Arun K

2016-11-01

Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides. Copyright © 2016 Elsevier GmbH. All rights reserved.

Biocontrol of Botrytis cinerea and Calonectria gracilis by eucalypts growth promoters Bacillus spp.

PubMed

Paz, Isabel Cristina Padula; Santin, Rita de Cássia Madail; Guimarães, Alexandre Martins; Rosa, Osmar Paulo Pereira da; Quecine, Maria Carolina; Silva, Michele de Cássia Pereira E; Azevedo, João Lúcio; Matsumura, Aida Terezinha Santos

2018-05-17

The clonal Eucalyptus plants are commonly obtained by vegetative propagation under a protected environment. This system improves the Botrytis cinerea and Calonectria spp infection on the young eucalypts plantings, resulting gray mold and cutting rot respectively. Currently, the unique available control method is based on chemicals. As alternative, novel methods to manage plant diseases, endophytic microorganisms could be an interesting alternative. Thus, we aimed to evaluate endophytic Bacillus isolated from eucalypts as a biocontrol agent against Botrytis cinerea and Calonectria gracilis, important fungal pathogens in the greenhouse, using clonal plantlets of E. urograndis. Eight endophytic strains of Bacillus, previously described as eucalyptus growth promoters, were evaluated in vitro and in vivo against Botrytis cinerea and Calonectria gracilis. The diffusible metabolites assay showed the potential of endophytic Bacillus to decrease the growth of both pathogens. Differences in the susceptibility of the pathogens to bacterial volatile metabolites were observed, B. cinerea showed more susceptible than Calonectria gracilis. In vivo assays, Bacillus amyloliquefaciens EUCB 10 demonstrated better overall reductions in these diseases. Based on the results obtained from the in vitro and in vivo analyses, we suggest that the endophytic B. amyloliquefaciens strain EUCB 10 constitutes a promising biocontrol agent against B. cinerea and Calonectria gracilis. Furthermore, this is the first reporting of B. amyloliquefaciens previously describe as plant growth promoter and also as potential control agent of B. cinerea and Calonectria gracilis to eucalyptus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fungal Genomics for Energy and Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor V.

2013-03-11

Genomes of fungi relevant to energy and environment are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). One of its projects, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts) by means of genome sequencing and analysis. New chapters of the Encyclopedia can be opened with user proposals to the JGI Community Sequencing Program (CSP). Another JGI project, the 1000 fungal genomes, explores fungal diversity on genome level at scale and is open for usersmore » to nominate new species for sequencing. Over 200 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supported by functional genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such parts suggested by comparative genomics and functional analysis in these areas are presented here.« less

Biocontrol Agents Increase the Specific Rate of Patulin Production by Penicillium expansum but Decrease the Disease and Total Patulin Contamination of Apples

PubMed Central

Zheng, Xiangfeng; Yang, Qiya; Zhang, Xiaoyun; Apaliya, Maurice T.; Ianiri, Giuseppe; Zhang, Hongyin; Castoria, Raffaello

2017-01-01

Synthetic fungicides are commonly employed for the control of postharvest diseases of fruits. However, due to health concerns about the use of these chemicals, alternative control methods including biocontrol based on antagonistic yeasts are gaining in popularity. In this study, we investigated the effects of two biocontrol yeasts, Rhodotorula mucilaginosa strain 3617 and Rhodotorula kratochvilovae strain LS11, on blue mold and patulin (PAT) contamination caused by Penicillium expansum strains PY and FS7 in artificially inoculated Fuji apples stored at 20°C for 9 days. To correlate the development of the P. expansum strains in yeast-treated and untreated apples with PAT production, we quantified their biomass in the infected fruits using a recently published quantitative real-time polymerase chain reaction method based on specific primers for patF, a gene from P. expansum that is involved in PAT biosynthesis. Both yeasts significantly reduced the disease incidence caused by the two strains of P. expansum up to 5–7 days of incubation, and lowered their biomass and the progression of symptoms up to 9 days. Interestingly, both yeasts strains increased the rate of PAT production (expressed as ng patulin/μg fungal DNA) by the two pathogenic strains. Nevertheless, both biocontrol agents reduced the total PAT contamination, especially in the case of P. expansum strain FS7, the higher PAT producer of the two tested P. expansum strains. Comparing between the yeast strains, R. kratochvilovae LS11 was more effective than R. mucilaginosa 3617 for the control of P. expansum. PMID:28713362

Identification and Characterization of Lipopeptides from Bacillus subtilis B1 Against Sapstain Fungus of Rubberwood Through MALDI-TOF-MS and RT-PCR.

PubMed

Sajitha, K L; Dev, Suma Arun; Maria Florence, E J

2016-07-01

Bacillus subtilis is a potent biocontrol agent producing a wide array of antifungal lipopeptides for the inhibition of fungal growth. B. subtilis B1 isolated from market-available compost provided an efficient control of rubberwood sapstain fungus, Lasiodiplodia theobromae. The current study is aimed to identify and characterize the lipopeptides responsible for the biocontrol of rubberwood sapstain fungus by Bacillus subtilis B1. The bacterial whole-cell surface extract from the dual culture of B. subtilis B1 and sapstain fungus (L. theobromae) was analysed using MALDI-TOF-MS. The protonated as well as sodium, potassium adducts of homologues of iturin C, surfactin, bacillomycin D and fengycin A and B were identified and expression of the lipopeptide biosynthetic genes could be confirmed through RT-PCR. This is the first report of mycobacillin and trimethylsilyl derivative of bacilysin during antagonism through MALDI-TOF-MS. MALDI-TOF-MS with RT-PCR offered easy platforms to characterize the antifungal lipopeptides. The identification of antifungal lipopeptides can lead to the formulation of prospective biocontrol by-products which have wide-scale utility.

Aflatoxin-producing fungi in maize field soils from sea level to over 2000 masl: a three year study in Sonora, Mexico.

PubMed

Ortega-Beltran, Alejandro; Jaime, Ramon; Cotty, Peter J

2015-04-01

Aflatoxins, highly toxic carcinogens produced by several members of Aspergillus section Flavi, contaminate crops in temperate zones. In the state of Sonora, Mexico, maize is cultivated from 0 to 2100 masl with diverse cultivation practices. This is typical of the nation. In order to design better sampling strategies across Mexico, aflatoxin-producing fungal communities associated with maize production during 2006, 2007, and 2008 in Sonora were investigated in four agro-ecological zones (AEZ) at varying elevation. Fungal communities were dominated by the Aspergillus flavus L strain morphotype (46%), but variation occurred between years and among AEZ. Several atoxigenic isolates with potential to be used as biocontrol agents for aflatoxin mitigation were detected in all AEZ. The characteristics of each AEZ had minimal influences on fungal community structure and should not be a major consideration for future sampling designs for Mexico. Insights into the dynamics and stability of aflatoxin-producing fungal communities across AEZ are discussed. Published by Elsevier Ltd.

Production of Gentisyl Alcohol from Phoma herbarum Endophytic in Curcuma longa L. and Its Antagonistic Activity Towards Leaf Spot Pathogen Colletotrichum gloeosporioides.

PubMed

Gupta, Suruchi; Kaul, Sanjana; Singh, Baljinder; Vishwakarma, Ram A; Dhar, Manoj K

2016-11-01

Endophytes from medicinal plants represent a potential source of bioactive compounds. During the present investigation, fungal endophytes were isolated from turmeric (Curcuma longa), an important medicinal plant. A total of 207 endophytic fungal isolates were obtained from the rhizome of C. longa L. They were grouped into seven genera based on morphological and molecular data. The fungal endophytes of C. longa were evaluated for antifungal activity against Colletotrichum gloeosporioides, the causal organism of leaf spot of turmeric. The disease is a major cause for economic loss in turmeric cultivation. Endophytic Phoma herbarum showed significant activity against C. gloeosporioides and was therefore selected for further studies. A compound gentisyl alcohol was isolated from P. herbarum which showed effective antagonism against C. gloeosporioides. The organism could therefore be used as a biocontrol agent against C. gloeosporioides.

A new method to evaluate the biocontrol potential of single spore isolates of fungal entomopathogens

PubMed Central

Posada, Francisco J.; Vega, Fernando E.

2005-01-01

Fifty Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) strains isolated from the coffee berry borer were used to develop a novel screening method aimed at selecting strains with the highest biocontrol potential. The screening method is based on percent insect mortality, average survival time, mortality distribution, percent spore germination, fungal life cycle duration, and spore production on the insect. Based on these parameters, only 11 strains merited further study. The use of a sound scientific protocol for the selection of promising fungal entomopathogens should lead to more efficient use of time, labor, and financial resources in biological control programs. PMID:17119619

Isolation and identification of biocontrol agent Streptomyces rimosus M527 against Fusarium oxysporum f. sp. cucumerinum.

PubMed

Lu, Dandan; Ma, Zheng; Xu, Xianhao; Yu, Xiaoping

2016-08-01

Actinomycetes have received considerable attention as biocontrol agents against fungal plant pathogens and as plant growth promoters. In this study, a total of 320 actinomycetes were isolated from various habitats in China. Among which, 77 strains have been identified as antagonistic activities against Fusarium oxysporum f. sp. cucumerinum which usually caused fusarium wilt of cucumber. Of these, isolate actinomycete M527 not only displayed broad-spectrum antifungal activity but also showed the strongest antagonistic activity against the spore germination of F. oxysporum f. sp. cucumerinum. In pot experiments, the results indicated that isolate M527 could promote the shoot growth and prevent the development of the disease on cucumber caused by F. oxysporum f. sp. cucumerinum. The control efficacy against seedling fusarium wilt of cucumber after M527 fermentation broth root-irrigation was up to 72.1% as compared to control. Based on 16S rDNA sequence analysis, the isolate M527 was identified as Streptomyces rimosus. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Indirect effects of host-specific biological control agents

Treesearch

Dean E. Pearson; Ragan M. Callaway

2003-01-01

Biological control is a crucial tool in the battle against biological invasions, but biocontrol agents can have a deleterious impact on native species. Recognition of risks associated with host shifting has increased the emphasis on host specificity of biocontrol agents for invasive weeds. However, recent studies indicate host-specific biocontrol agents can...

Apparent competition can compromise the safety of highly specific biocontrol agents.

PubMed

Carvalheiro, Luisa G; Buckley, Yvonne M; Ventim, Rita; Fowler, Simon V; Memmott, Jane

2008-07-01

Despite current concern about the safety of biological control of weeds, assessing the indirect impacts of introduced agents is not common practice. Using 17 replicate food webs, we demonstrate that the use of a highly host-plant specific weed biocontrol agent, recently introduced into Australia, is associated with declines of local insect communities. The agent shares natural enemies (predators and parasitoids) with seed herbivore species from native plants, so apparent competition is the most likely cause for these losses. Both species richness and abundance in insect communities (seed herbivores and their parasitoids) were negatively correlated with the abundance of the biocontrol agent. Local losses of up to 11 species (dipteran seed herbivores and parasitoids) took place as the biocontrol agent abundance increased. Ineffective biocontrol agents that remain highly abundant in the community are most likely to have persistent, indirect negative effects. Our findings suggest that more investment is required in pre-release studies on the effectiveness of biocontrol agents, as well as in post-release studies assessing indirect impacts, to avoid or minimize the release of potentially damaging species.

Mycobiome of Cysts of the Soybean Cyst Nematode Under Long Term Crop Rotation

PubMed Central

Hu, Weiming; Strom, Noah; Haarith, Deepak; Chen, Senyu; Bushley, Kathryn E.

2018-01-01

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe (Phylum Nematoda), is a major pathogen of soybean. It causes substantial yield losses worldwide and is difficult to control because the cyst protects the eggs which can remain viable for nearly a decade. Crop rotation with non-host crops and use of biocontrol organisms such as fungi and bacteria offer promising approaches, but remain hampered by lack of knowledge of the biology of nematode parasitic organisms. We used a high-throughput metabarcoding approach to characterize fungal communities associated with the SCN cyst, a microenvironment in soil that may harbor both nematode parasites and plant pathogens. SCN cysts were collected from a long-term crop rotation experiment in Southeastern Minnesota at three time points over two growing seasons to characterize diversity of fungi inhabiting cysts and to examine how crop rotation and seasonal variation affects fungal communities. A majority of fungi in cysts belonged to Ascomycota and Basidiomycota, but the presence of several early diverging fungal subphyla thought to be primarily plant and litter associated, including Mortierellomycotina and Glomeromycotina (e.g., arbuscular mycorrhizal fungi), suggests a possible role as nematode egg parasites. Species richness varied by both crop rotation and season and was higher in early years of crop rotation and in fall at the end of the growing season. Crop rotation and season also impacted fungal community composition and identified several classes of fungi, including Eurotiomycetes, Sordariomycetes, and Orbiliomycetes (e.g., nematode trapping fungi), with higher relative abundance in early soybean rotations. The relative abundance of several genera was correlated with increasing years of soybean. Fungal communities also varied by season and were most divergent at midseason. The percentage of OTUs assigned to Mortierellomycotina_cls_Incertae_sedis and Sordariomycetes increased at midseason, while Orbiliomycetes decreased at midseason, and Glomeromycetes increased in fall. Ecological guilds of fungi containing an animal-pathogen lifestyle, as well as potential egg-parasitic taxa previously isolated from parasitized SCN eggs, increased at midseason. The animal pathogen guilds included known (e.g., Pochonia chlamydosporia) and new candidate biocontrol organisms. This research advances knowledge of the ecology of nematophagous fungi in agroecosystems and their use as biocontrol agents of the SCN. PMID:29615984

Method To immobilize the aphid-pathogenic fungus erynia neoaphidis in an alginate matrix for biocontrol

PubMed

Shah; Aebi; Tuor

1998-11-01

Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.

Recent taxonomy changes and their impact on biocontrol agents

USDA-ARS?s Scientific Manuscript database

The revolution in DNA sequencing technology has led to and improved understanding of genetics and taxonomy of biocontrol agents. Our lab recently reported the genomes of some important Bacillus bacterial biocontrol agents, which in turn resulted in a change of taxonomy for these commercially importa...

Prevention of fungal spoilage in food products using natural compounds: A review.

PubMed

Ribes, Susana; Fuentes, Ana; Talens, Pau; Barat, Jose Manuel

2017-04-10

The kingdom Fungi is the most important group of microorganism contaminating food commodities, and chemical additives are commonly used in the food industry to prevent fungal spoilage. However, the increasing consumer concern about synthetic additives has led to their substitution by natural compounds in foods. The current review provides an overview of using natural agents isolated from different sources (plants, animals, and microorganisms) as promising antifungal compounds, including information about their mechanism of action and their use in foods to preserve and prolong shelf life. Compounds derived from plants, chitosan, lactoferrin, and biocontrol agents (lactic acid bacteria, antagonistic yeast, and their metabolites) are able to control the decay caused by fungi in a wide variety of foods. Several strategies are employed to reduce the drawbacks of some antifungal agents, like their incorporation into oil-in-water emulsions and nanoemulsions, edible films and active packaging, and their combination with other natural preservatives. These strategies facilitate the addition of volatile agents into food products and, improve their antifungal effectiveness. Moreover, biological agents have been investigated as one of the most promising options in the control of postharvest decay. Numerous mechanisms of action have been elucidated and different approaches have been studied to enhance their antifungal effectiveness.

Gene expression profile of the plant pathogen Fusarium graminearum under the antagonistic effect of Pantoea agglomerans.

PubMed

Pandolfi, V; Jorge, E C; Melo, C M R; Albuquerque, A C S; Carrer, H

2010-07-06

The pathogenic fungus Fusarium graminearum is an ongoing threat to agriculture, causing losses in grain yield and quality in diverse crops. Substantial progress has been made in the identification of genes involved in the suppression of phytopathogens by antagonistic microorganisms; however, limited information regarding responses of plant pathogens to these biocontrol agents is available. Gene expression analysis was used to identify differentially expressed transcripts of the fungal plant pathogen F. graminearum under antagonistic effect of the bacterium Pantoea agglomerans. A macroarray was constructed, using 1014 transcripts from an F. graminearum cDNA library. Probes consisted of the cDNA of F. graminearum grown in the presence and in the absence of P. agglomerans. Twenty-nine genes were either up (19) or down (10) regulated during interaction with the antagonist bacterium. Genes encoding proteins associated with fungal defense and/or virulence or with nutritional and oxidative stress responses were induced. The repressed genes coded for a zinc finger protein associated with cell division, proteins containing cellular signaling domains, respiratory chain proteins, and chaperone-type proteins. These data give molecular and biochemical evidence of response of F. graminearum to an antagonist and could help develop effective biocontrol procedures for pathogenic plant fungi.

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease.

PubMed

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes ( sfp, ituC and bmyB ) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight ( p = 0.000) and the antibacterial activity in vitro ( p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol ( p = 0.004) and the reduction in gall weight ( p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo . Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens . These strains were found to produce either surfactin or surfactin and iturin lipopeptides. In conclusion, our study presented a new and effective method to evaluate the biocontrol ability of antagonistic Bacillus strains against crown gall disease that could increase the efficiency of screening method of biocontrol agents. Besides, the selected strains could be used as novel biocontrol agents against pathogenic Agrobacterium tumefaciens strains.

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease

PubMed Central

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes (sfp, ituC and bmyB) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight (p = 0.000) and the antibacterial activity in vitro (p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol (p = 0.004) and the reduction in gall weight (p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo. Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens. These strains were found to produce either surfactin or surfactin and iturin lipopeptides. In conclusion, our study presented a new and effective method to evaluate the biocontrol ability of antagonistic Bacillus strains against crown gall disease that could increase the efficiency of screening method of biocontrol agents. Besides, the selected strains could be used as novel biocontrol agents against pathogenic Agrobacterium tumefaciens strains. PMID:28855909

Fate of biological control introductions: monitoring an Australian fungal pathogen of grasshoppers in North America.

PubMed Central

Bidochka, M J; Walsh, S R; Ramos, M E; St Leger, R J; Silver, J C; Roberts, D W

1996-01-01

In North America there are two generally recognized pathotypes (pathotypes 1 and 2) of the fungus Entomophaga grylli which show host-preferential infection of grasshopper subfamilies. Pathotype 3, discovered in Australia, has a broader grasshopper host range and was considered to be a good biocontrol agent. Between 1989 and 1991 pathotype 3 was introduced at two field sites in North Dakota. Since resting spores are morphologically indistinguishable among pathotypes, we used pathotype-specific DNA probes to confirm pathotype identification in E. grylli-infected grasshoppers collected at the release sites in 1992, 1993, and 1994. In 1992, up to 23% of E. grylli-infected grasshoppers of the subfamilies Melanoplinae, Oedipodinae, and Gomphocerinae were infected by pathotype 3, with no infections > 1 km from the release sites. In 1993, pathotype 3 infections declined to 1.7%. In 1994 grasshopper populations were low and no pathotype 3 infections were found. The frequency of pathotype 3 infection has declined to levels where its long-term survival in North America is questionable. Analyses of biocontrol releases are critical to evaluating the environmental risks associated with these ecological manipulations, and molecular probes are powerful tools for monitoring biocontrol releases. Images Fig. 1 PMID:8570660

Quorum signaling mycotoxins: A new risk strategy for bacterial biocontrol of Fusarium verticillioides and other endophytic fungal species?

USDA-ARS?s Scientific Manuscript database

Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. All bacteria communicate via cell-dependent signals, which...

Virulence and site of infection of the fungus, Hirsutella thompsonii, to the honey bee ectoparasitic mite, Varroa destructor.

PubMed

Peng, Christine Y S; Zhou, Xinsheng; Kaya, Harry K

2002-11-01

The Varroa mite, Varroa destructor, is recognized as the most serious pest of both managed and feral Western honey bee (Apis mellifera) in the world. The mite has developed resistance to fluvalinate, an acaricide used to control it in beehives, and fluvalinate residues have been found in the beeswax, necessitating an urgent need to find alternative control measures to suppress this pest. Accordingly, we investigated the possibility of using the fungus, Hirsutella thompsonii, as a biocontrol agent of the Varroa mite. Among the 9 isolates of H. thompsonii obtained from the University of Florida and the USDA, only the 3 USDA isolates (ARSEF 257, 1947 and 3323) were infectious to the Varroa mite in laboratory tests. The mite became infected when it was allowed to walk on a sporulating H. thompsonii culture for 5 min. Scanning electron micrographs revealed that the membranous arolium of the mite leg sucker is the focus of infection where the fungal conidia adhered and germinated. The infected mites died from mycosis, with the lethal times to kill 50% (LT(50)s) dependent on the fungal isolates. Thus, the LT(50)s were 52.7, 77.2, and 96.7h for isolates 3323, 257, and 1947, respectively. Passage of H. thompsonii through Varroa mite three times significantly reduced the LT(50)s of isolates 257 and 1947 (P<0.05) but not the LT(50) of isolate 3323. The fungus did not infect the honey bee in larval, prepupal, pupal, and adult stages under our laboratory rearing conditions. Our encouraging results suggest that some isolates of H. thompsonii have the potential to be developed as a biocontrol agent for V. destructor. However, fungal infectivity against the mites under beehive conditions needs to be studied before any conclusion can be made.

Tailoring biocontrol to maximize top-down effects: on the importance of underlying site fertility.

PubMed

Hovick, Stephen M; Carson, Walter P

2015-01-01

The degree to which biocontrol agents impact invasive plants varies widely across landscapes, often for unknown reasons. Understanding this variability can help optimize invasive species management while also informing our understanding of trophic linkages. To address these issues, we tested three hypotheses with contrasting predictions regarding the likelihood of biocontrol success. (1) The biocontrol effort hypothesis: invasive populations are regulated primarily by top-down effects, predicting that increased biocontrol efforts alone (e.g., more individuals of a given biocontrol agent or more time since agent release) will enhance biocontrol success. (2) The relative fertility hypothesis: invasive populations are regulated primarily by bottom-up effects, predicting that nutrient enrichment will increase dominance by invasives and thus reduce biocontrol success, regardless of biocontrol efforts. (3) The fertility-dependent biocontrol effort hypothesis: top-down effects will only regulate invasive populations if bottom-up effects are weak. It predicts that greater biocontrol efforts will increase biocontrol success, but only in low-nutrient sites. To test these hypotheses, we surveyed 46 sites across three states with prior releases of Galerucella beetles, the most common biocontrol agents used against invasive purple loosestrife (Lythrum salicaria). We found strong support for the fertility-dependent biocontrol effort hypothesis, as biocontrol success occurred most often with greater biocontrol efforts, but only in low-fertility sites. This result held for early stage metrics of biocontrol success (higher Galerucella abundance) and ultimate biocontrol outcomes (decreased loosestrife plant size and abundance). Presence of the invasive grass Phalaris arundinacea was also inversely related to loosestrife abundance, suggesting that biocontrol-based reductions in loosestrife made secondary invasion by P. arundinacea more likely. Our data suggest that low-nutrient sites be prioritized for loosestrife biocontrol and that future monitoring account for variation in site fertility or work to mitigate it. We introduce a new framework that integrates our findings with conflicting patterns previously reported from other biocontrol systems, proposing a unimodal relationship whereby nutrient availability enhances biocontrol success in low-nutrient sites but hampers it in high-nutrient sites. Our results represent one of the first examples of biocontrol success depending on site fertility, which has the potential to inform biocontrol-based management decisions across entire regions and among contrasting systems.

De novo Genome Assembly of the Fungal Plant Pathogen Pyrenophora semeniperda

PubMed Central

Soliai, Marcus M.; Meyer, Susan E.; Udall, Joshua A.; Elzinga, David E.; Hermansen, Russell A.; Bodily, Paul M.; Hart, Aaron A.; Coleman, Craig E.

2014-01-01

Pyrenophora semeniperda (anamorph Drechslera campulata) is a necrotrophic fungal seed pathogen that has a wide host range within the Poaceae. One of its hosts is cheatgrass (Bromus tectorum), a species exotic to the United States that has invaded natural ecosystems of the Intermountain West. As a natural pathogen of cheatgrass, P. semeniperda has potential as a biocontrol agent due to its effectiveness at killing seeds within the seed bank; however, few genetic resources exist for the fungus. Here, the genome of P. semeniperda isolate assembled from sequence reads of 454 pyrosequencing is presented. The total assembly is 32.5 Mb and includes 11,453 gene models encoding putative proteins larger than 24 amino acids. The models represent a variety of putative genes that are involved in pathogenic pathways typically found in necrotrophic fungi. In addition, extensive rearrangements, including inter- and intrachromosomal rearrangements, were found when the P. semeniperda genome was compared to P. tritici-repentis, a related fungal species. PMID:24475219

Antifungal modes of action of Saccharomyces and other biocontrol yeasts against fungi isolated from sour and grey rots.

PubMed

Nally, M C; Pesce, V M; Maturano, Y P; Rodriguez Assaf, L A; Toro, M E; Castellanos de Figueroa, L I; Vazquez, F

2015-07-02

The aim of this study was to determine the putative modes of action of 59 viticultural yeasts (31 Saccharomyces and 28 non-Saccharomyces) that inhibited fungi isolated from sour and grey rot in grapes. Inhibition of fungal mycelial growth by metabolites, enzyme activities (laminarinases, chitinases), antifungal volatiles, competition for nutrients (siderophores, Niche Overlap Index (NOI)), inhibition of fungal spore germination and decreased germinal tube length and induction of resistance were assayed. Biofungicide yeasts were classified into "antifungal patterns", according to their mechanisms of action. Thirty isolates presented at least two of the mechanisms assayed. We propose that inhibition of fungal mycelial growth by metabolites, laminarinases, competition for nutrients, inhibition of fungal spore germination and decreased germinal tube length, and antifungal volatiles by Saccharomyces and non-Saccharomyces viticultural yeasts is used as putative biocontrol mechanisms against phytopathogenic fungi. Twenty-four different antifungal patterns were identified. Siderophore production (N)and a combination of siderophore production and NOI>0.92 (M)were the most frequent antifungal patterns observed in the biofungicide yeasts assayed. Elucidation of these mechanisms could be useful for optimization of an inoculum formulation, resulting in a more consistent control of grey and sour rot with Saccharomyces and non-Saccharomyces biocontrol yeasts. Copyright © 2015 Elsevier B.V. All rights reserved.

Benefits of pre-release population genetics: a case study using Psyttalia lounsburyi, a biocontrol agent of the olive fruit fly in California

USDA-ARS?s Scientific Manuscript database

From a pest management perspective, limited knowledge on the genetics of released biocontrol agents has been repeatedly considered as one possible cause of failures in classical biological control. Introduced biocontrol agents are expected to experience a loss in genetic diversity as the result of s...

Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt.

PubMed

Morsy, Ahmed A; Elshahawy, Ibrahim E

2016-05-01

Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt. Typical anthracnose symptoms were observed on the stems of imported D. sanderiana samples. The pathogen was isolated, demonstrated to be pathogenic based on Koch's rule and identified as Colletotrichum dracaenophilum. The optimum temperature for its growth ranges from 25 to 30 °C, maintained for 8 days. Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed over 100 ppm. The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth. To the best of our knowledge, this report describes the first time that this pathogen was observed on D. sanderiana in Egypt.

Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt

PubMed Central

Morsy, Ahmed A.; Elshahawy, Ibrahim E.

2016-01-01

Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt. Typical anthracnose symptoms were observed on the stems of imported D. sanderiana samples. The pathogen was isolated, demonstrated to be pathogenic based on Koch’s rule and identified as Colletotrichum dracaenophilum. The optimum temperature for its growth ranges from 25 to 30 °C, maintained for 8 days. Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed over 100 ppm. The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth. To the best of our knowledge, this report describes the first time that this pathogen was observed on D. sanderiana in Egypt. PMID:27222738

Phenylacetic acid-producing Rhizoctonia solani represses the biosynthesis of nematicidal compounds in vitro and influences biocontrol of Meloidogyne incognita in tomato by Pseudomonas fluorescens strain CHA0 and its GM derivatives.

PubMed

Siddiqui, I A; Shaukat, S S

2005-01-01

The aim of the present investigation was to determine the influence of Rhizoctonia solani and its pathogenicity factor on the production of nematicidal agent(s) by Pseudomonas fluorescens strain CHA0 and its GM derivatives in vitro and nematode biocontrol potential by bacterial inoculants in tomato. One (Rs7) of the nine R. solani isolates from infected tomato roots inhibited seedling emergence and caused root rot in tomato. Thin layer chromatography revealed that culture filtrates of two isolates (Rs3 and Rs7) produced brown spots at Rf-values closely similar to synthetic phenylacetic acid (PAA), a phytotoxic factor. Filtrates from isolate Rs7, amended with the growth medium of P. fluorescens, markedly repressed nematicidal activity and PhlA'-'LacZ reporter gene expression of the bacteria in vitro. On the contrary, isolate Rs4 enhanced nematicidal potential of a 2,4-diacetylphloroglucinol overproducing mutant, CHA0/pME3424, of P. fluorescens strain CHA0 in vitro. Therefore, R. solani isolates Rs4 and Rs7 were tested more rigorously for their potential to influence biocontrol effectiveness of the bacterial agents. Methanol extract of the culture filtrates of PAA-producing isolate Rs7 resulting from medium amended with phenylalanine enhanced fungal repression of the production of nematicidal agents by bacteria, while amendments with zinc or molybdenum eliminated such fungal repression, thereby restoring bacterial potential to cause nematode mortality in vitro. A pot experiment was carried out, 3-week-old tomato seedlings were infested with R. solani isolates Rs4 or Rs7 and/or inoculated with Meloidogyne incognita, the root-knot nematode. The infested soil was treated with aqueous cell suspensions (10(8) CFU) of P. fluorescens strain CHA0 or its GM derivatives or left untreated (as a control). Observations taken 45 days after nematode inoculation revealed that, irrespective of the bacterial treatments, galling intensity per gram of fresh tomato roots was markedly higher in soil amended with isolate Rs4 than in Rs7-amended soils. Soil amendments with R. solani and the bacterial antagonists resulted in substantial reductions of the number of galls per gram of root. These results are contradictory to those obtained under in vitro conditions where culture filtrates of PAA-positive Rs7 repressed the production of nematicidal compounds. Plants grown in Rs7-amended soils, with or without bacterial inoculants, had lesser shoot and root weights than plants grown in nonamended or Rs4-amended soils. Moreover, amendments with Rs7 substantially retarded root growth and produced necrotic lesions that reduced the number of entry sites for invasion and subsequent infection by nematodes. Populations of P. fluorescens in the tomato rhizosphere were markedly higher in Rs7-amended soils. PAA-producing virulent R. solani drastically affects the potential of P. fluorescens to cause death of M. incognita juveniles in vitro and influences bacterial effectiveness to suppress nematodes in tomato roots. As most agricultural soils are infested with root-infecting fungi, including R. solani, it is likely that some PAA-producing isolates of the fungus may also be isolated from such soils. The inhibitory effect of PAA-producing R. solani on the biosynthesis of nematicidal agent(s) critical in biocontrol may reduce or even eliminate the effectiveness of fluorescent pseudomonads against root-knot nematodes, both in nursery beds and in field conditions. Introduction of bacterial inoculants, for the control of any plant pathogen, should be avoided in soils infested with PAA-producing R. solani. Alternatively, the agents could be applied together with an appropriate quantity of fungicide or chemicals such as zinc to create an environment more favourable for bacterial biocontrol action.

A novel, image analysis-based method for the evaluation of in vitro antagonism.

PubMed

Szekeres, András; Leitgeb, Balázs; Kredics, László; Manczinger, László; Vágvölgyi, Csaba

2006-06-01

A novel method is proposed for the accurate evaluation of in vitro antagonism. Based on the measurement of areas of the fungal colonies, biocontrol indices were calculated, which are characteristic to the antagonistic Trichoderma strains. These indices provide a useful tool to describe the biocontrol abilities of fungi.

Population structure of Aspergillus flavus before and after biocontrol treatment

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus is a fungal pathogen of many important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, North Carolina, over a period of two years. Plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of which are ...

United States Department of Agriculture-Agricultural Research Service research programs in biological control of plant diseases.

PubMed

Roberts, Daniel P; Lohrke, Scott M

2003-01-01

A number of USDA-ARS programs directed at overcoming impediments to the use of biocontrol agents on a commercial scale are described. These include improvements in screening techniques, taxonomic studies to identify beneficial strains more precisely, and studies on various aspects of the large-scale production of biocontrol agents. Another broad area of studies covers the ecological aspects of biocontrol agents-their interaction with the pathogen, with the plant and with other aspects of the environmental complex. Examples of these studies are given and their relevance to the further development and expansion of biocontrol agents is discussed.

Biocontrol of fouling pests: Effect of diversity, identity and density of control agents.

PubMed

Atalah, Javier; Newcombe, Emma M; Zaiko, Anastasija

2016-04-01

Augmentative biocontrol, using native natural enemies, has been suggested as a promising tool to control marine biofouling pests on artificial structures. However, there are still important knowledge gaps to be addressed before biocontrol can be considered as a management tool. In a field experiment on floating marine structures we examined intra- and interspecific consumer interactions among biocontrol agents on different surface orientations. We tested the effect of identity, density and diversity of three invertebrates (the 11-arm seastar Coscinasterias muricata, the sea urchin Evechinus chloroticus and the gastropod Cook's turban Cookia sulcata) to reduce established biofouling and to prevent fouling growth on defouled surfaces. High densities of biocontrol agents were not more effective at fouling control (cover and biomass) than low densities. Nor did multi-species treatments function more effectively than mono-specific ones. However, biocontrol agent identity was important, with the 11-arm seastar and Cook's turban being the most effective at fouling reduction and prevention, respectively. Surface orientation had a strong effect on the effectiveness of control agents, with the best results obtained on vertical compared to diagonal and underside surfaces. This study confirmed the potential of biocontrol as a management tool for marine pest, indicating that identity is more important than richness and density of control agents. It also highlighted the limitations of this approach on diagonal and underside surfaces, where control agents have limited retention ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae).

PubMed

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae ). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyce s bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae . The ability of various S treptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae . In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae)

PubMed Central

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M.; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10–30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents. PMID:28144236

The Cerato-Platanin protein Epl-1 from Trichoderma harzianum is involved in mycoparasitism, plant resistance induction and self cell wall protection

PubMed Central

Gomes, Eriston Vieira; Costa, Mariana do Nascimento; de Paula, Renato Graciano; Ricci de Azevedo, Rafael; da Silva, Francilene Lopes; Noronha, Eliane F.; José Ulhoa, Cirano; Neves Monteiro, Valdirene; Elena Cardoza, Rosa; Gutiérrez, Santiago; Nascimento Silva, Roberto

2015-01-01

Trichoderma harzianum species are well known as biocontrol agents against important fungal phytopathogens. Mycoparasitism is one of the strategies used by this fungus in the biocontrol process. In this work, we analyzed the effect of Epl-1 protein, previously described as plant resistance elicitor, in expression modulation of T. harzianum genes involved in mycoparasitism process against phytopathogenic fungi; self cell wall protection and recognition; host hyphae coiling and triggering expression of defense-related genes in beans plants. The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host mycoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain. These data indicated the involvement T. harzianum Epl-1 in self and host interaction and also recognition of T. harzianum as a symbiotic fungus by the bean plants. PMID:26647876

AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

PubMed

Elsen, A; Gervacio, D; Swennen, R; De Waele, D

2008-07-01

Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

The Cerato-Platanin protein Epl-1 from Trichoderma harzianum is involved in mycoparasitism, plant resistance induction and self cell wall protection.

PubMed

Gomes, Eriston Vieira; Costa, Mariana do Nascimento; de Paula, Renato Graciano; de Azevedo, Rafael Ricci; da Silva, Francilene Lopes; Noronha, Eliane F; Ulhoa, Cirano José; Monteiro, Valdirene Neves; Cardoza, Rosa Elena; Gutiérrez, Santiago; Silva, Roberto Nascimento

2015-12-09

Trichoderma harzianum species are well known as biocontrol agents against important fungal phytopathogens. Mycoparasitism is one of the strategies used by this fungus in the biocontrol process. In this work, we analyzed the effect of Epl-1 protein, previously described as plant resistance elicitor, in expression modulation of T. harzianum genes involved in mycoparasitism process against phytopathogenic fungi; self cell wall protection and recognition; host hyphae coiling and triggering expression of defense-related genes in beans plants. The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host mycoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain. These data indicated the involvement T. harzianum Epl-1 in self and host interaction and also recognition of T. harzianum as a symbiotic fungus by the bean plants.

Cystofilobasidium infirmominiatum as a biocontrol agent of postharvest diseases of apple and citrus

USDA-ARS?s Scientific Manuscript database

Two psycrotrophic yeasts isolated from the surface of lemons have been selected as biocontrol agents of the most common postharvest diseases of apples and citrus that develops during cold storage. The biocontrol yeasts were identified as Cystofilobasidium infirmominiatum and Leucosporidium scottii....

Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome.

PubMed

Zhang, Tao; Chaturvedi, Vishnu; Chaturvedi, Sudha

2015-01-01

White-nose syndrome (WNS), an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd), the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp) from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1) Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C), (2) Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3) Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4) Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp), (5) Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6) Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites.

Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome

PubMed Central

Zhang, Tao; Chaturvedi, Vishnu; Chaturvedi, Sudha

2015-01-01

White-nose syndrome (WNS), an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd), the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp) from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1) Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C), (2) Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3) Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4) Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp), (5) Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6) Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites. PMID:26509269

Biocontrol of Alternaria alternata on cherry tomato fruit by use of marine yeast Rhodosporidium paludigenum Fell & Tallman.

PubMed

Wang, Yifei; Bao, Yihong; Shen, Danhong; Feng, Wu; Yu, Ting; Zhang, Jia; Zheng, Xiao Dong

2008-04-30

The basidiomycetous yeast Rhodosporidium paludigenum Fell & Tallman isolated from the south of East China Sea was evaluated for its activity in reducing postharvest decay of cherry tomatoes caused by Alternaria alternata in vitro and in vivo tests. The results showed that washed cell suspension of R. paludigenum provided better control of A. alternata than any other treatment, while the autoclaved cell culture failed to provide protection against the pathogen. The concentration of antagonist had significant effect on biocontrol effectiveness in vivo: when the concentration of the washed yeast cell suspension was used at 1 x 10(9)cells/ml, the percentage rate of black rot of cherry tomato fruit was only 37%, which was remarkably lower than that treated with water (the control) after 5days of incubation at 25 degrees C. Furthermore, a great biocontrol efficacy of R. paludigenum was observed when it was applied prior to inoculation with A. alternata: the longer the incubation time of R. paludigenum, the lower disease incidence would be. However, there was little efficacy when R. paludigenum was applied after A. alternata inoculation. In addition, on the wounds of cherry tomato, it was observed that R. paludigenum grew rapidly increasing 50-fold during the first 12h at 25 degrees C. To the best of our knowledge, this is a first report concerning that the marine yeast R. paludigenum could be used as a biocontrol agent of postharvest fungal disease.

Leaf Treatments with a Protein-Based Resistance Inducer Partially Modify Phyllosphere Microbial Communities of Grapevine

PubMed Central

Cappelletti, Martina; Perazzolli, Michele; Antonielli, Livio; Nesler, Andrea; Torboli, Esmeralda; Bianchedi, Pier L.; Pindo, Massimo; Puopolo, Gerardo; Pertot, Ilaria

2016-01-01

Protein derivatives and carbohydrates can stimulate plant growth, increase stress tolerance, and activate plant defense mechanisms. However, these molecules can also act as a nutritional substrate for microbial communities living on the plant phyllosphere and possibly affect their biocontrol activity against pathogens. We investigated the mechanisms of action of a protein derivative (nutrient broth, NB) against grapevine downy mildew, specifically focusing on the effects of foliar treatments on plant defense stimulation and on the composition and biocontrol features of the phyllosphere microbial populations. NB reduced downy mildew symptoms and induced the expression of defense-related genes in greenhouse- and in vitro-grown plants, indicating the activation of grapevine resistance mechanisms. Furthermore, NB increased the number of culturable phyllosphere bacteria and altered the composition of bacterial and fungal populations on leaves of greenhouse-grown plants. Although, NB-induced changes on microbial populations were affected by the structure of indigenous communities originally residing on grapevine leaves, degrees of disease reduction and defense gene modulation were consistent among the experiments. Thus, modifications in the structure of phyllosphere populations caused by NB application could partially contribute to downy mildew control by competition for space or other biocontrol strategies. Particularly, changes in the abundance of phyllosphere microorganisms may provide a contribution to resistance induction, partially affecting the hormone-mediated signaling pathways involved. Modifying phyllosphere populations by increasing natural biocontrol agents with the application of selected nutritional factors can open new opportunities in terms of sustainable plant protection strategies. PMID:27486468

Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidl, Verena; Song, Lifu; Lindquist, Erika

2009-11-30

Background: Fungi of the genus Trichoderma are effective mycoparasites an for this reason used as biocontrol agents agents plant pathogenic fungi. The ability to recognize, combat and finally besiege and kill the prey are essential skills for this process. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. This study aims at uncovering transcriptional responses occurring in the mycoparasite Trichoderma atroviride when being confronted with a potential prey. Results: T. atroviride was confronted with two fungal preys, Botrytis cinerea and Rhizoctonia solani, and cDNAs prepared from mycelia immediately before getting into physical contactmore » with them (“onset of mycoparasitism”), and compared with such prepared from mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes each, were obtained from each of these three conditions. 65 genes, represented by 439 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof verified by expression analysis. They comprised 18 KOG groups, but were most abundant from those including posttranslational processing (159 from 183 ESTs), and amino acid metabolism (70 of 84 ESTs), respectively. Several heat shock factors and tRNA synthases were particularly abundant. Metabolic network analysis confirmed the upregulation of the amino acid biosynthesic and the lipid catabolic capacity. Conclusion: Analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions including strong stress response, sensing of nitrogen shortage and lipid catabolism. The data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for breeding of biocontrol strains by recombinant techniques.« less

Mass-Rearing Hydrellia Pakistanae Deonier and H. balciunasi Bock for the Management of Hydrilla verticillata

DTIC Science & Technology

2009-06-01

capability. Mass Rearing: The ability to mass-produce large numbers of high quality insect biocontrol agents can be a tremendous asset when...implementing a biocontrol program. Common sense would dictate that releasing a high number of agents allows for higher establishment success, more rapid...varying densities of biocontrol agent (costs estimated using a constant weight). Table 1. Hypothetical calculation of Hydrellia pakistanae production cost

Biocontrol of foliar pathogens: mechanisms and application.

PubMed

Elad, Y

2003-01-01

Biocontrol offers attractive alternatives or supplements to the use of conventional methods for plant disease management. Vast experience has been gained in the biocontrol of plant diseases. Prevention of infection by biocontrol agents or suppression of disease is based on various modes of action. Pathogens are typically affected by certain modes of actions and not by others according to their nature (i.e. biotrophs vs. necrotrophs). Resistance in the host plant may be induced locally or systemically by either live or dead cells of the biocontrol agent and may affect pathogens of various groups. As some pathogens are negatively affected by lake of nutrients in the infection court, competition for nutrients and space was long recognized as antagonism trait. Antibiosis and hyperparasitism affect pathogens of various groups. Other valid mechanisms are reduction of the saprophytic ability and reducing spore dissemination. Recently it was revealed that restraining of pathogenicity factors of the pathogens, i.e. host hydrolyzing proteins or reactive oxygen species takes place when biocontrol is used. It is likely that several modes of action concomitantly participate in pathogens suppression but the relative importance of each one of them is not clear. Examples of effective prevention of infection in the phyllosphere that rely on multiple modes of action will be demonstrated with Trichodermo harzianum T39 (TRICHODEX), Bacillus mycoides and Pichia guilermondii, a filamentous fungus, bacterium and yeast biocontrol agents, respectively. Several commercial products based on microorganisms have been developed and are starting to penetrate the market. However, large-scale use is still limited because of variability and inconsistency of biocontrol activity. In some cases this may be caused by sensitivity of the biocontrol agents to environmental influences. Ways to overcome biocontrol limitations and to improve its efficacy are i. integration of biocontrol with chemical fungicides on a calendar basis or according to ecological requirements of the biocontrol agents relying on the advise of a decision support system; ii. introduction of two or more biocontrol agents in a mixture, assuming that each one of them has different ecological requirements and/or different modes of action. Implementation of one (or more) of these approaches, using biocontrol preparations mentioned above lowered the variability and increased the consistency of disease suppression. The expected long-term result of the implementation of these suggested strategies is reduced risk of uncontrolled epidemics and increase of confidence of growers in using this non-chemical control measure on a large scale.

Penicillium oxalicum reduces the number of cysts and juveniles of potato cyst nematodes.

PubMed

Martinez-Beringola, M L; Salto, T; Vázquez, G; Larena, I; Melgarejo, P; De Cal, A

2013-07-01

To test the biocontrol potential of Penicillium oxalicum, a biocontrol agent against fungal diseases and against the potato cyst nematodes (PCNs), Globodera pallida and Globodera rostochiensis. We tested the effect of P. oxalicum on the nematode cysts under laboratory conditions or in soil microcosms. A reduction in the rate of G. pallida juveniles hatching by P. oxalicum was observed when root diffusates from the 'Monalisa' and the 'Désirée' potato cultivar were used (98·6 and 74·1% reduction, respectively). However, the rate of G. pallida juveniles hatching was not significantly reduced when root diffusates from the 'San Pedro' tomato cultivar were used. Penicillium oxalicum also significantly reduced the ability of the G. rostochiensis juveniles to hatch (30·9% reduction) when root diffusates of the 'Désirée' potato cultivars were used. Penicillium oxalicum treatment of the soil significantly reduced the number of G. pallida cysts that were recovered from the soil of each pot that contained the 'Désirée' potato cultivar. Our results show that P. oxalicum is a potential biocontrol inoculant for protecting potato crops against PCNs. Penicillium oxalicum has potential to be used in order to reduce PCNs. Journal of Applied Microbiology © 2013 The Society for Applied Microbiology.

Comparative transcriptome and gene co-expression network analysis reveal genes and signaling pathways adaptively responsive to varied adverse stresses in the insect fungal pathogen, Beauveria bassiana.

PubMed

He, Zhangjiang; Zhao, Xin; Lu, Zhuoyue; Wang, Huifang; Liu, Pengfei; Zeng, Fanqin; Zhang, Yongjun

2018-01-01

Sensing, responding, and adapting to the surrounding environment are crucial for all living organisms to survive, proliferate, and differentiate in their biological niches. Beauveria bassiana is an economically important insect-pathogenic fungus which is widely used as a biocontrol agent to control a variety of insect pests. The fungal pathogen unavoidably encounters a variety of adverse environmental stresses and defense response from the host insects during application of the fungal agents. However, few are known about the transcription response of the fungus to respond or adapt varied adverse stresses. Here, we comparatively analyzed the transcriptome of B. bassiana in globe genome under the varied stationary-phase stresses including osmotic agent (0.8 M NaCl), high temperature (32 °C), cell wall-perturbing agent (Congo red), and oxidative agents (H 2 O 2 or menadione). Total of 12,412 reads were obtained, and mapped to the 6767 genes of the B. bassiana. All of these stresses caused transcription responses involved in basal metabolism, cell wall construction, stress response or cell rescue/detoxification, signaling transduction and gene transcription regulation, and likely other cellular processes. An array of genes displayed similar transcription patterns in response to at least two of the five stresses, suggesting a shared transcription response to varied adverse stresses. Gene co-expression network analysis revealed that mTOR signaling pathway, but not HOG1 MAP kinase pathway, played a central role in regulation the varied adverse stress responses, which was verified by RNAi-mediated knockdown of TOR1. Our findings provided an insight of transcription response and gene co-expression network of B. bassiana in adaptation to varied environments. Copyright © 2017 Elsevier Inc. All rights reserved.

Transformation with green fluorescent protein of Trichoderma harzianum 1051, a strain with biocontrol activity against Crinipellis perniciosa, the agent of witches'-broom disease of cocoa.

PubMed

Inglis, Peter W.; Queiroz, Paulo R.; Valadares-Inglis, M. Cléria

1999-04-01

A plasmid vector for fungal expression of an enhanced, red-shifted variant of the Aequoria victoriae green fluorescent protein was constructed by fusion of the EGFP gene to the highly expressed Aspergillus nidulans gpd promoter and the A. nidulans trpC terminator. This construction was introduced by cotransformation, using benomyl selection, into Trichoderma harzianum strain 1051, a strain being evaluated for the biological control of witches'-broom disease of cocoa caused by Crinipellis perniciosa. Epifluorescence microscopy was used to monitor germination and attachment of stable transformant conidia on the surface of C. perniciosa hyphae.

The transcription factor SKN7 regulates conidiation, thermotolerance, apoptotic-like cell death and parasitism in the nematode endoparasitic fungus Hirsutella minnesotensis

PubMed Central

Hussain, Muzammil; Hamid, M. Imran; Wang, Niuniu; Bin, Lin; Xiang, Meichun; Liu, Xingzhong

2016-01-01

The transcription factor SKN7 is a highly conserved protein among fungi and was initially recognized as a response regulator that protects cells from oxidative stress and maintains cell wall integrity in yeast. Orthologs of SKN7 are extensively present in biocontrol agents of plant pathogens, but they had not been functionally characterized. Here, we identified and characterized the transcription factor SKN7 in the nematode endoparasitic fungus Hirsutella minnesotensis. Null mutant lacking HIM-SKN7 (HIM_03620), which was generated by a gene disruption strategy, demonstrated reduced conidiation, increased sensitivity to high temperature, hydrogen peroxide, mannitol and ethanol, and reduced fungal resistance to farnesol. However, over-expression mutant showed increased conidial production, thermotolerance and resistance to farnesol, suggesting that HIM-SKN7 regulates antiapoptotic-like cell death in H. minnesotensis. Moreover, the results showed that in null mutant, H. minnesotensis had decreased endoparasitic ability as compared to wild type and over-expression strain. During the infection process, the relative expression of the HIM-SKN7 gene was significantly induced in the wild type and over-expression strain. The results of the present study advance our understanding of the functions of the SKN7 gene in biocontrol agents, in particular, nematode endoparasitic fungi. PMID:27436205

Inhibitory Effect of Essential Oils on Aspergillus ochraceus Growth and Ochratoxin A Production

PubMed Central

Selvaraj, Jonathan Nimal; Wang, Yan; Zhao, Yueju; Zhou, Lu; Liu, Xiao; Liu, Yang

2014-01-01

Ochratoxin A (OTA) is a mycotoxin which is a common contaminant in grains during storage. Aspergillus ochraceus is the most common producer of OTA. Essential oils play a crucial role as a biocontrol in the reduction of fungal contamination. Essential oils namely natural cinnamaldehyde, cinnamon oil, synthetic cinnamaldehyde, Litsea citrate oil, citral, eugenol, peppermint, eucalyptus, anise and camphor oils, were tested for their efficacy against A. ochraceus growth and OTA production by fumigation and contact assays. Natural cinnamaldehyde proved to be the most effective against A. ochraceus when compared to other oils. Complete fungal growth inhibition was obtained at 150–250 µL/L with fumigation and 250–500 µL/L with contact assays for cinnamon oil, natural and synthetic cinnamaldehyde, L. citrate oil and citral. Essential oils had an impact on the ergosterol biosynthesis and OTA production. Complete inhibition of ergosterol biosynthesis was observed at ≥100 µg/mL of natural cinnamaldehyde and at 200 µg/mL of citral, but total inhibition was not observed at 200 µg/mL of eugenol. But, citral and eugenol could inhibit the OTA production at ≥75 µg/mL and ≥150 µg/mL respectively, while natural cinnamaldehyde couldn’t fully inhibit OTA production at ≤200 µg/mL. The inhibition of OTA by natural cinnamaldehyde is mainly due to the reduction in fungal biomass. However, citral and eugenol could significant inhibit the OTA biosynthetic pathway. Also, we observed that cinnamaldehyde was converted to cinnamic alcohol by A. ochraceus, suggesting that the antimicrobial activity of cinnamaldehyde was mainly attributed to its carbonyl aldehyde group. The study concludes that natural cinnamaldehyde, citral and eugenol could be potential biocontrol agents against OTA contamination in storage grains. PMID:25255251

Cheatgrass (Bromus tectorum) biocontrol using indigenous fungal pathogens

Treesearch

Susan E. Meyer; David L. Nelson; Suzette Clement; Julie Beckstead

2008-01-01

Cheatgrass (Bromus tectorum) is an exotic winter annual grass weed that has invaded millions of hectares in the Intermountain West. Restoration of cheatgrass-invaded wildlands is generally impractical without some form of cheatgrass control. We are investigating the possibility of manipulating indigenous fungal pathogens that already occur on...

Trichodiene production in a Trichoderma harzianum erg1-silenced strain provides evidence of the importance of the sterol biosynthetic pathway in inducing plant defense-related gene expression

USDA-ARS?s Scientific Manuscript database

Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both ...

Molecular evolution and phylogenetic analysis of biocontrol genes acquired from SCoT polymorphism of mycoparasitic Trichoderma koningii inhibiting phytopathogen Rhizoctonia solani Kuhn.

PubMed

Gajera, H P; Hirpara, Darshna G; Katakpara, Zinkal A; Patel, S V; Golakiya, B A

2016-11-01

The biocontrol agent Trichoderma (T. harzianum, T. viride, T. virens, T. hamantum, T. koningii, T. pseudokoningii and Trichoderma species) inhibited variably (15.32 - 88.12%) the in vitro growth of Rhizoctonia solani causing root rot in cotton. The T. koningii MTCC 796 evidenced highest (88.12%) growth inhibition of test pathogen followed by T. viride NBAII Tv23 (85.34%). Scanning electron microscopic study confirmed mycoparasitism for MTCC 796 and Tv23 which were capable of completely overgrowing on R. solani by degrading mycelia, coiling around the hyphae with hook-like structures. The antagonists T. harzianum NBAII Th1 and, T. virens NBAII Tvs12 exhibited strong antibiosis and formed 2-4 mm zone of inhibition for 70.28% and 46.62%, respectively growth inhibition of test pathogen. Mycoparasitism is a strong mode of action for biocontrol activity compared with antibiosis. The antagonists Trichoderma strains were performed for start codon targeted (SCoT) polymorphism to acquire biocontrol genes from potent antagonist. The six unique SCoT fragments amplified by genomic DNA of best mycoparasitic antagonist MTCC 796 strain are subjected to DNA sequencing resulted to confirm two functional sequences for activity related to biocontrol genes. The phylogenetic and molecular evolution of functional 824 bp of SCoT-3 (920) and 776 bp of SCoT-6 (806) fragments signify sequence homology with biocontrol genes endochitinase (partial cds of 203 amino acids) and novel hmgR genes (partial cds of 239 amino acids), respectively and the same were annotated and deposited in NCBI GenBank database. The hmgR gene is liable to be express hmg - CoA reductase which is a key enzyme for regulation of terpene biosynthesis and mycoparasitic strains produced triterpenes during antagonism to inhibit growth of fungal pathogen as evidenced with GC-MS profile. The biocontrol genes are found in best antagonist T. koningii MTCC 796 for mycoparasitic activity to restrain the growth of test pathogen R. solani. Copyright © 2016 Elsevier B.V. All rights reserved.

Environmental factors affect the activity of biocontrol agents against ochratoxigenic Aspergillus carbonarius on wine grape.

PubMed

De Curtis, F; de Felice, D V; Ianiri, G; De Cicco, V; Castoria, R

2012-09-17

The influence of temperature and relative humidity (RH) on the activity of three biocontrol agents-the yeast Metschnikowia pulcherrima LS16 and two strains of the yeast-like fungus Aureobasidium pullulans LS30 and AU34-2-against infection by A. carbonarius and ochratoxin A (OTA) accumulation in wine grape berries was investigated in lab-scale experiments. The presence of wounds on grape skin dramatically favored infection of berries by A. carbonarius strain A1102, since unwounded berries showed very low levels of infection at all conditions of RH and temperature tested. Artificially wounded berries pre-treated with the biocontrol agents were inoculated with the ochratoxigenic A. carbonarius strain A1102 and were incubated for 5 days at two levels of RH (60% and 100%) and three different temperatures (20, 25 and 30 °C). The three biocontrol agents were able to prevent infections at 60% RH and 20 °C. At 60% RH and 25 °C only strain AU34-2 achieved some protection on day 5, whereas at 30 °C a limited biocontrol efficacy was evident only up to day 2. At 100% RH, LS16, LS30 and AU34-2 showed effective protection of grape berries at 20 °C until the 5th day of incubation. The three biocontrol agents achieved significant protection at higher temperatures only until the 2nd day after the beginning of the experiment: all three strains at 25 °C, and only strain LS16 at 30 °C. After 5 days, the three biocontrol agents were able to significantly reduce the level of OTA in berries at all the conditions tested. This occurred even when protection from infection was not significant, except at 30 °C and 100% of RH for all the three strains, and at 25 °C and 100% of RH for strain LS16. The biocontrol agents displayed a higher rate of colonization on grape berries at 20 and 25 °C than at 30 °C. The higher value of RH (100%) appeared to increase the rate of colonization, in particular at 20 and 25 °C. Taken together, our results emphasize the significant influence of environmental factors on the effectiveness of biocontrol against A. carbonarius as well as on OTA contamination in wine grape berries, and the need for biocontrol agents that can cope with the environmental conditions that are conducive to attack by A. carbonarius. Copyright © 2012 Elsevier B.V. All rights reserved.

A numerical study of combined use of two biocontrol agents with different biocontrol mechanisms in controlling foliar pathogens.

PubMed

Xu, X-M; Jeffries, P; Pautasso, M; Jeger, M J

2011-09-01

Effective use of biocontrol agents is an important component of sustainable agriculture. A previous numerical study of a generic model showed that biocontrol efficacy was greatest for a single biocontrol agent (BCA) combining competition with mycoparasitism or antibiosis. This study uses the same mathematical model to investigate whether the biocontrol efficacy of combined use of two BCAs with different biocontrol mechanisms is greater than that of a single BCA with either or both of the two mechanisms, assuming that two BCAs occupy the same host tissue as the pathogen. Within the parameter values considered, a BCA with two biocontrol mechanisms always outperformed the combined use of two BCAs with a single but different biocontrol mechanism. Similarly, combined use of two BCAs with a single but different biocontrol mechanism is shown to be far less effective than that of a single BCA with both mechanisms. Disease suppression from combined use of two BCAs was very similar to that achieved by the more efficacious one. As expected, a higher BCA introduction rate led to increased disease suppression. Incorporation of interactions between two BCAs did not greatly affect the disease dynamics except when a mycoparasitic and, to a lesser extent, an antibiotic-producing BCA was involved. Increasing the competitiveness of a mycoparasitic BCA over a BCA whose biocontrol mechanism is either competition or antibiosis may lead to improved biocontrol initially and reduced fluctuations in disease dynamics. The present study suggests that, under the model assumptions, combined use of two BCAs with different biocontrol mechanisms in most cases only results in control efficacies similar to using the more efficacious one alone. These predictions are consistent with published experimental results, suggesting that combined use of BCAs should not be recommended without clear understanding of their main biocontrol mechanisms and relative competitiveness, and experimental evaluation.

Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

PubMed Central

Manhas, Rajesh K.; Kaur, Talwinder

2016-01-01

Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75–80%) and vigor index (1167–1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers. PMID:28018402

Relationship of microbial communities and suppressiveness of Trichoderma fortified composts for pepper seedlings infected by Phytophthora nicotianae.

PubMed

Ros, Margarita; Raut, Iulia; Santisima-Trinidad, Ana Belén; Pascual, Jose Antonio

2017-01-01

The understanding of the dynamic of soil-borne diseases is related to the microbial composition of the rhizosphere which is the key to progress in the field of biological control. Trichoderma spp. is commonly used as a biological control agent. The use of next generation sequencing approaches and quantitative PCR are two successful approaches to assess the effect of using compost as substrate fortified with two Trichoderma strains (Trichoderma harzianum or Trichoderma asperellum) on bacterial and fungal communities in pepper rhizosphere infected with Phytophthora nicotianae. The results showed changes in the bacterial rhizosphere community not attributed to the Trichoderma strain, but to the pathogen infection, while, fungi were not affected by pathogen infection and depended on the type of substrate. The Trichoderma asperellum fortified compost was the most effective combination against the pathogen. This could indicate that the effect of fortified composts is greater than compost itself and the biocontrol effect should be attributed to the Trichoderma strains rather than the compost microbiota, although some microorganisms could help with the biocontrol effect.

Relationship of microbial communities and suppressiveness of Trichoderma fortified composts for pepper seedlings infected by Phytophthora nicotianae

PubMed Central

Ros, Margarita; Raut, Iulia; Santisima-Trinidad, Ana Belén; Pascual, Jose Antonio

2017-01-01

The understanding of the dynamic of soil-borne diseases is related to the microbial composition of the rhizosphere which is the key to progress in the field of biological control. Trichoderma spp. is commonly used as a biological control agent. The use of next generation sequencing approaches and quantitative PCR are two successful approaches to assess the effect of using compost as substrate fortified with two Trichoderma strains (Trichoderma harzianum or Trichoderma asperellum) on bacterial and fungal communities in pepper rhizosphere infected with Phytophthora nicotianae. The results showed changes in the bacterial rhizosphere community not attributed to the Trichoderma strain, but to the pathogen infection, while, fungi were not affected by pathogen infection and depended on the type of substrate. The Trichoderma asperellum fortified compost was the most effective combination against the pathogen. This could indicate that the effect of fortified composts is greater than compost itself and the biocontrol effect should be attributed to the Trichoderma strains rather than the compost microbiota, although some microorganisms could help with the biocontrol effect. PMID:28346470

Biocontrol Activity of Volatile-Producing Bacillus megaterium and Pseudomonas protegens against Aspergillus flavus and Aflatoxin Production on Stored Rice Grains

PubMed Central

Mannaa, Mohamed; Oh, Ji Yeon

2017-01-01

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles. PMID:29138628

Repressed Beauveria bassiana Infections in Delia antiqua due to Associated Microbiota.

PubMed

Zhou, Fangyuan; Wu, Xiaoqing; Xu, Letian; Guo, Shuhai; Chen, Guanhong; Zhang, Xinjian

2018-05-23

Insects form both mutualistic and antagonistic relationships with microbes, and some antagonistic microbes have been used as biocontrol agents (BCAs) in pest management. Contextually, BCAs may be inhibited by beneficial insect symbionts, which can become potential barriers for entomopathogen-dependent pest biocontrol. Thus, by using the symbioses formed by one devastating dipteran pest, Delia antiqua, and its associated microbes as a model system, we sought to determine whether the antagonistic interaction between BCAs and microbial symbionts could affect the outcome of entomopathogen-dependent pest biocontrol. The result showed that in contrast to non-axenic D. antiqua larvae, i.e., onion maggots, axenic larvae lost resistance to the entomopathogenic Beauveria bassiana, and the re-inoculation of microbiota increased the resistance of axenic larvae to B. bassiana. Furthermore, bacteria, including Citrobacter freundii, Enterobacter ludwigii, Pseudomonas protegens, Serratia plymuthica, Sphingobacterium faecium, and Stenotrophomonas maltophilia, frequently isolated from larvae suppressed B. bassiana conidia germination and hyphal growth, and the re-inoculation of specific individual bacteria enhanced the resistance of axenic larvae to B. bassiana. Bacteria associated with larvae, including C. freundii, E. ludwigii, P. protegens, S. plymuthica, S. faecium, and S. maltophilia, can inhibit B. bassiana infection. Removing the microbiota can suppress larval resistance to fungal infection. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Induction of defense responses against Magnaporthe oryzae in rice seedling by a new potential biocontrol agent Streptomyces JD211.

PubMed

Shao, Zhengying; Li, Zhang; Fu, Yanhui; Wen, Yangping; Wei, Saijin

2018-06-14

The induced resistance against plant pathogens via biocontrol agents is considered as an eco-friendly and promising strategy. In this study, the induced resistance against Magnaporthe oryzae (M. oryzae) in rice seedling by a new potential biocontrol agent Streptomyces JD211 (JD211) was evaluated. The effects of JD211 on defense-related enzymes activities and defense genes expression were investigated. The biocontrol efficacy of different JD211 concentrations was different, and the treatment of 10 g kg -1 JD211 achieved the highest biocontrol efficacy. Activities of catalase, phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase significantly increased in the presence of JD211. The gene expression level of both PAL and pathogenesis related protein 1 increased when rice seedlings were inoculated with JD211 alone or co-inoculated with M. oryzae, and the expression level of chitinase gene was enhanced by JD211 in the later stage. All results suggested that JD211 could increase the rice resistance by stimulating a series of defense responses, which was the result of induced systemic resistance by JD211. This work will provide a new biocontrol agent against Magnaporthe oryzae in rice seedling. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew.

PubMed

Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

2015-01-01

Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway.

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

PubMed

Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

2017-10-01

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

Physiological and biochemical characterization of Trichoderma harzianum, a biological control agent against soilborne fungal plant pathogens.

PubMed Central

Grondona, I; Hermosa, R; Tejada, M; Gomis, M D; Mateos, P F; Bridge, P D; Monte, E; Garcia-Acha, I

1997-01-01

Monoconidial cultures of 15 isolates of Trichoderma harzianum were characterized on the basis of 82 morphological, physiological, and biochemical features and 99 isoenzyme bands from seven enzyme systems. The results were subjected to numerical analysis which revealed four distinct groups. Representative sequences of the internal transcribed spacer 1 (ITS 1)-ITS 2 region in the ribosomal DNA gene cluster were compared between groups confirming this distribution. The utility of the groupings generated from the morphological, physiological, and biochemical data was assessed by including an additional environmental isolate in the electrophoretic analysis. The in vitro antibiotic activity of the T. harzianum isolates was assayed against 10 isolates of five different soilborne fungal plant pathogens: Aphanomyces cochlioides, Rhizoctonia solani, Phoma betae, Acremonium cucurbitacearum, and Fusarium oxysporum f. sp. radicis lycopersici. Similarities between levels and specificities of biological activity and the numerical characterization groupings are both discussed in relation to antagonist-specific populations in known and potential biocontrol species. PMID:9251205

Antagonistic activity of fungi of Olea europaea L. against Colletotrichum acutatum.

PubMed

Landum, Miguel C; Félix, Maria do Rosário; Alho, Joana; Garcia, Raquel; Cabrita, Maria João; Rei, Fernando; Varanda, Carla M R

2016-02-01

Fungi naturally present in olive trees were identified and tested for their antagonistic potential against Colletotrichum acutatum. A total of 14 isolates were identified, 12 belonged to genera Alternaria, Epicoccum, Fusarium, Aspergillus, Anthrinium, Chaetomium, Diaporthe, Nigrospora, one to family Xylariaceae and one was unclassified. All fungal isolates showed some inhibitory action over the growth of C. acutatum during dual culture growth, however, when agar-diffusible tests were performed only five fungal isolates caused C. acutatum growth inhibition: Alternaria sp. isolate 2 (26.8%), the fungus from Xylariaceae family (14.3%), Alternaria sp. isolate 1 (10.7%); Diaporthe sp. (10.7%), Nigrospora oryzae (3.5%). Volatile substances produced by these isolates were identified through gas-chromatography techniques, as phenylethyl alcohol, 4-methylquinazoline, benzothiazole, benzyl alcohol, lilial, galaxolide, among others. These inhibitory volatiles could play a significant role in reduction of C. acutatum expansion in olive and their study as potential biocontrol agents should be further explored. Copyright © 2015 Elsevier GmbH. All rights reserved.

Transcriptomic insight into pathogenicity-associated factors of Conidiobolus obscurus, an obligate aphid-pathogenic fungus belonging to Entomopthoromycota.

PubMed

Wang, Jianghong; Zhou, Xiang; Guo, Kai; Zhang, Xinqi; Lin, Haiping; Montalva, Cristian

2018-01-16

Conidiobolus obscurus is a widespread fungal entomopathogen with aphid biocontrol potential. This study focused on a de novo transcriptomic analysis of C. obscurus. A number of pathogenicity-associated factors were annotated for the first time from the assembled 17 231 fungal unigenes, including those encoding subtilisin-like proteolytic enzymes (Pr1s), trypsin-like proteases, metalloproteases, carboxypeptidases and endochitinases. Many of these genes were transcriptionally up-regulated by at least twofold in mycotized cadavers compared with the in vitro fungal cultures. The resultant transcriptomic database was validated by the transcript levels of three selected pathogenicity-related genes quantified from different in vivo and in vitro material in real-time quantitative polymerase chain reaction (PCR). The involvement of multiple Pr1 proteases in the first stage of fungal infection was also suggested. Interestingly, a unique cytolytic (Cyt)-like δ-endotoxin gene was highly expressed in both mycotized cadavers and fungal cultures, and was more or less distinct from its homologues in bacteria and other fungi. Our findings provide the first global insight into various pathogenicity-related genes in this obligate aphid pathogen and may help to develop novel biocontrol strategy against aphid pests. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Transcriptomic responses of a simplified soil microcosm to a plant pathogen and its biocontrol agent reveal a complex reaction to harsh habitat.

PubMed

Perazzolli, Michele; Herrero, Noemí; Sterck, Lieven; Lenzi, Luisa; Pellegrini, Alberto; Puopolo, Gerardo; Van de Peer, Yves; Pertot, Ilaria

2016-10-27

Soil microorganisms are key determinants of soil fertility and plant health. Soil phytopathogenic fungi are one of the most important causes of crop losses worldwide. Microbial biocontrol agents have been extensively studied as alternatives for controlling phytopathogenic soil microorganisms, but molecular interactions between them have mainly been characterised in dual cultures, without taking into account the soil microbial community. We used an RNA sequencing approach to elucidate the molecular interplay of a soil microbial community in response to a plant pathogen and its biocontrol agent, in order to examine the molecular patterns activated by the microorganisms. A simplified soil microcosm containing 11 soil microorganisms was incubated with a plant root pathogen (Armillaria mellea) and its biocontrol agent (Trichoderma atroviride) for 24 h under controlled conditions. More than 46 million paired-end reads were obtained for each replicate and 28,309 differentially expressed genes were identified in total. Pathway analysis revealed complex adaptations of soil microorganisms to the harsh conditions of the soil matrix and to reciprocal microbial competition/cooperation relationships. Both the phytopathogen and its biocontrol agent were specifically recognised by the simplified soil microcosm: defence reaction mechanisms and neutral adaptation processes were activated in response to competitive (T. atroviride) or non-competitive (A. mellea) microorganisms, respectively. Moreover, activation of resistance mechanisms dominated in the simplified soil microcosm in the presence of both A. mellea and T. atroviride. Biocontrol processes of T. atroviride were already activated during incubation in the simplified soil microcosm, possibly to occupy niches in a competitive ecosystem, and they were not further enhanced by the introduction of A. mellea. This work represents an additional step towards understanding molecular interactions between plant pathogens and biocontrol agents within a soil ecosystem. Global transcriptional analysis of the simplified soil microcosm revealed complex metabolic adaptation in the soil environment and specific responses to antagonistic or neutral intruders.

Identification of Putative Coffee Rust Mycoparasites via Single-Molecule DNA Sequencing of Infected Pustules

PubMed Central

Marino, John A.; Perfecto, Ivette; Vandermeer, John

2015-01-01

The interaction of crop pests with their natural enemies is a fundament to their control. Natural enemies of fungal pathogens of crops are poorly known relative to those of insect pests, despite the diversity of fungal pathogens and their economic importance. Currently, many regions across Latin America are experiencing unprecedented epidemics of coffee rust (Hemileia vastatrix). Identification of natural enemies of coffee rust could aid in developing management strategies or in pinpointing species that could be used for biocontrol. In the present study, we characterized fungal communities associated with coffee rust lesions by single-molecule DNA sequencing of fungal rRNA gene bar codes from leaf discs (≈28 mm2) containing rust lesions and control discs with no rust lesions. The leaf disc communities were hyperdiverse in terms of fungi, with up to 69 operational taxonomic units (putative species) per control disc, and the diversity was only slightly reduced in rust-infected discs, with up to 63 putative species. However, geography had a greater influence on the fungal community than whether the disc was infected by coffee rust. Through comparisons between control and rust-infected leaf discs, as well as taxonomic criteria, we identified 15 putative mycoparasitic fungi. These fungi are concentrated in the fungal family Cordycipitaceae and the order Tremellales. These data emphasize the complexity of diverse fungi of unknown ecological function within a leaf that might influence plant disease epidemics or lead to the development of species for biocontrol of fungal disease. PMID:26567299

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola.

PubMed

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie; Hélias, Valérie; Faure, Denis

2016-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

PubMed Central

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie

2015-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. PMID:26497457

An endophytic Streptomyces sp. strain DHV3-2 from diseased root as a potential biocontrol agent against Verticillium dahliae and growth elicitor in tomato (Solanum lycopersicum).

PubMed

Cao, Peng; Liu, Chongxi; Sun, Pengyu; Fu, Xuepeng; Wang, Shaoxian; Wu, Fengzhi; Wang, Xiangjing

2016-12-01

Plant endophytes play important roles in biocontrol of plant diseases. Actinomycetes are used for biocontrol of fungal diseases caused by Verticillium dahliae. Many studies have focused on the endophytic actinomycetes isolated from the roots of healthy plants, but few on those from the roots of diseased plants. In the present research, actinomycetes were isolated from the roots of diseased and healthy tomato plants, respectively. The results showed that, in total, 86 endophytic actinomycetes were isolated for screening of their antimicrobial activities, 8 of which showed antagonism to V. dahliae in vitro. Among the 8 antagonistic strains, 5 (out of 36) were from the roots of diseased plants, with inhibition diameter zones ranging from 11.2 to 18.2 mm, whereas 3 (out of 50) were from the roots of healthy plants, with inhibition diameter zones ranging from 11.5 to 15.5 mm. Endophytic strain DHV3-2 was isolated from the root of a diseased plant and demonstrated a potent effect against V. dahliae and other pathogenic fungi by showing the largest inhibition diameter zones among all the eight antagonistic strains. Thus, strain DHV3-2 was chosen to investigate its biological control efficacies in vivo. Further study showed that the disease incidence and disease severity indices of tomato Verticillium wilt decreased significantly (P < 0.05). We also found that the plant shoot fresh weight and height increased greatly (P < 0.05) upon treatment with strain DHV3-2 compared to the plants uninoculated in greenhouse conditions. Root colonization showed that strain DHV3-2 had the higher root-colonizing capacity in the roots of infected plants compared with the roots of healthy plants. This isolate was identified as Streptomyces sp. based on morphological characteristics and 16S rRNA gene analysis. In conclusion, the roots of diseased tomato plants are a potential reservoir of biological control actinomycetes, and Streptomyces sp. strain DHV3-2 is a potential biocontrol agent against V. dahliae and growth elicitor in tomato.

Entomopathogenic fungus as a biological control for an important vector of livestock disease: the Culicoides biting midge.

PubMed

Ansari, Minshad Ali; Pope, Edward C; Carpenter, Simon; Scholte, Ernst-Jan; Butt, Tariq M

2011-01-10

The recent outbreak of bluetongue virus in northern Europe has led to an urgent need to identify control measures for the Culicoides (Diptera: Ceratopogonidae) biting midges that transmit it. Following successful use of the entomopathogenic fungus Metarhizium anisopliae against larval stages of biting midge Culicoides nubeculosus Meigen, we investigated the efficacy of this strain and other fungi (Beauveria bassiana, Isaria fumosorosea and Lecanicillium longisporum) as biocontrol agents against adult C. nubeculosus in laboratory and greenhouse studies. Exposure of midges to 'dry' conidia of all fungal isolates caused significant reductions in survival compared to untreated controls. Metarhizium anisopliae strain V275 was the most virulent, causing a significantly decrease in midge survival compared to all other fungal strains tested. The LT(50) value for strain V275 was 1.42 days compared to 2.21-3.22 days for the other isolates. The virulence of this strain was then further evaluated by exposing C. nubeculosus to varying doses (10(8)-10(11) conidia m(-2)) using different substrates (horse manure, damp peat, leaf litter) as a resting site. All exposed adults were found to be infected with the strain V275 four days after exposure. A further study exposed C. nubeculosus adults to 'dry' conidia and 'wet' conidia (conidia suspended in 0.03% aq. Tween 80) of strain V275 applied to damp peat and leaf litter in cages within a greenhouse. 'Dry' conidia were more effective than 'wet' conidia, causing 100% mortality after 5 days. This is the first study to demonstrate that entomopathogenic fungi are potential biocontrol agents against adult Culicoides, through the application of 'dry' conidia on surfaces (e.g., manure, leaf litter, livestock) where the midges tend to rest. Subsequent conidial transmission between males and females may cause an increased level of fungi-induced mortality in midges thus reducing the incidence of disease.

Entomopathogenic Fungus as a Biological Control for an Important Vector of Livestock Disease: The Culicoides Biting Midge

PubMed Central

Ansari, Minshad Ali; Pope, Edward C.; Carpenter, Simon; Scholte, Ernst-Jan; Butt, Tariq M.

2011-01-01

Background The recent outbreak of bluetongue virus in northern Europe has led to an urgent need to identify control measures for the Culicoides (Diptera: Ceratopogonidae) biting midges that transmit it. Following successful use of the entomopathogenic fungus Metarhizium anisopliae against larval stages of biting midge Culicoides nubeculosus Meigen, we investigated the efficacy of this strain and other fungi (Beauveria bassiana, Isaria fumosorosea and Lecanicillium longisporum) as biocontrol agents against adult C. nubeculosus in laboratory and greenhouse studies. Methodology/Findings Exposure of midges to ‘dry’ conidia of all fungal isolates caused significant reductions in survival compared to untreated controls. Metarhizium anisopliae strain V275 was the most virulent, causing a significantly decrease in midge survival compared to all other fungal strains tested. The LT50 value for strain V275 was 1.42 days compared to 2.21–3.22 days for the other isolates. The virulence of this strain was then further evaluated by exposing C. nubeculosus to varying doses (108–1011 conidia m−2) using different substrates (horse manure, damp peat, leaf litter) as a resting site. All exposed adults were found to be infected with the strain V275 four days after exposure. A further study exposed C. nubeculosus adults to ‘dry’ conidia and ‘wet’ conidia (conidia suspended in 0.03% aq. Tween 80) of strain V275 applied to damp peat and leaf litter in cages within a greenhouse. ‘Dry’ conidia were more effective than ‘wet’ conidia, causing 100% mortality after 5 days. Conclusion/Significance This is the first study to demonstrate that entomopathogenic fungi are potential biocontrol agents against adult Culicoides, through the application of ‘dry’ conidia on surfaces (e.g., manure, leaf litter, livestock) where the midges tend to rest. Subsequent conidial transmission between males and females may cause an increased level of fungi-induced mortality in midges thus reducing the incidence of disease. PMID:21264343

In vitro effects of flutriafol and azoxystrobin on Beauvaria bassiana and its efficacy against Tetranychus urticae.

PubMed

Gatarayiha, Mutimura C; Laing, Mark D; Miller, Ray M

2010-07-01

Testing the compatibility of chemical pesticides and fungal biocontrol agents is necessary if these two agents are to be applied together in the integrated management of plant pests and diseases. In this study, the fungicides azoxystrobin (a strobilurin) and flutriafol (a triazole) were tested in vitro for their effects on germination of conidia and mycelial growth of Beauveria bassiana (Bals.) Vuill. and in bioassay for their effect on fungal activity against Tetranychus urticae Koch. The fungicides were tested at three different concentrations [recommended rate for field use (1 x X) and the dilutions 10(-1)x X and 10(-2)x X]. Flutriafol inhibited growth of mycelia and germination of the fungal conidia at all concentrations tested in vitro, and also reduced the efficacy of B. bassiana in bioassays against mites. The inhibitive effect of azoxystrobin in vitro varied with the concentration applied. A significant effect was observed at 1 x X and 10(-1)x X concentrations on both the germination of conidia and mycelia growth. At 10(-2)x X concentration, azoxystrobin showed little effect on B. bassiana. However, when this fungicide was tested in bioassays, none of the concentrations reduced B. bassiana activity against mites. Azoxystrobin was most compatible with B. bassiana, while flutriafol was the most harmful. Further studies are required to confirm the negative effect of flutriafol on B. bassiana activity. Copyright (c) 2010 Society of Chemical Industry.

Genome Sequence of the Biocontrol Strain Pseudomonas fluorescens F113

PubMed Central

Redondo-Nieto, Miguel; Barret, Matthieu; Morrisey, John P.; Germaine, Kieran; Martínez-Granero, Francisco; Barahona, Emma; Navazo, Ana; Sánchez-Contreras, María; Moynihan, Jennifer A.; Giddens, Stephen R.; Coppoolse, Eric R.; Muriel, Candela; Stiekema, Willem J.; Rainey, Paul B.; Dowling, David; O'Gara, Fergal; Martín, Marta

2012-01-01

Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms. PMID:22328765

Analysis of whitefly transcriptional responses to Beauveria bassiana infection reveals new insights into insect-fungus interactions.

PubMed

Xia, Jun; Zhang, Chang-Rong; Zhang, Shan; Li, Fang-Fang; Feng, Ming-Guang; Wang, Xiao-Wei; Liu, Shu-Sheng

2013-01-01

The fungal pathogen, Beauveria bassiana, is an efficient biocontrol agent against a variety of agricultural pests. A thorough understanding of the basic principles of insect-fungus interactions may enable the genetic modification of Beauveria bassiana to enhance its virulence. However, the molecular mechanism of insect response to Beauveria bassiana infection is poorly understood, let alone the identification of fungal virulent factors involved in pathogenesis. Here, next generation sequencing technology was applied to examine the expression of whitefly (Bemisia tabaci) genes in response to the infection of Beauveria bassiana. Results showed that, compared to control, 654 and 1,681genes were differentially expressed at 48 hours and 72 hours post-infected whiteflies, respectively. Functional and enrichment analyses indicated that the DNA damage stimulus response and drug metabolism were important anti-fungi strategies of the whitefly. Mitogen-activated protein kinase (MAPK) pathway was also likely involved in the whitefly defense responses. Furthermore, the notable suppression of general metabolism and ion transport genes observed in 72 hours post-infected B. tabaci might be manipulated by fungal secreted effectors. By mapping the sequencing tags to B. bassiana genome, we also identified a number of differentially expressed fungal genes between the early and late infection stages. These genes are generally associated with fungal cell wall synthesis and energy metabolism. The expression of fungal cell wall protein genes might play an important role in fungal pathogenesis and the dramatically up-regulated enzymes of carbon metabolism indicate the increasing usage of energy during the fungal infection. To our knowledge, this is the first report on the molecular mechanism of fungus-whitefly interactions. Our results provide a road map for future investigations on insect-pathogen interactions and genetically modifying the fungus to enhance its efficiency in whitefly control.

Proactive Management of Fermentation and Formulation Interactions to Improve Biocontrol Product Performance

USDA-ARS?s Scientific Manuscript database

The key components of biocontrol product development—discovery, fermentation, and formulation—are interactively linked to each other and ultimately to product performance. To identify biocontrol agents suited for commercial development, our discovery programs utilize a cumulative ranking system tha...

Direct plantlet inoculation with soil or insect-associated fungi may control cabbage root fly maggots.

PubMed

Razinger, Jaka; Lutz, Matthias; Schroers, Hans-Josef; Palmisano, Marilena; Wohler, Christian; Urek, Gregor; Grunder, Jürg

2014-07-01

A potential Delia radicum biological control strategy involving cauliflower plantlet inoculation with various fungi was investigated in a series of laboratory and glasshouse experiments. In addition to entomopathogenic fungi, fungi with a high rhizosphere competence and fungi with the ability to survive as saprotrophs in soil were tested. The following fungal species were evaluated in the experiments: Trichoderma atroviride, T. koningiopsis, T. gamsii, Beauveria bassiana, Metharhizium anisopliae, M. brunneum and Clonostachys solani. A commercial carbosulfan-based insecticide was used as a positive control. Additionally, two commercial products, one based on B. bassiana (Naturalis) and one on Bacillus thuringiensis (Delfin) were used as reference biocontrol agents. The aims were (i) to assess the pathogenicity of the selected fungal isolates to Delia radicum, (ii) to evaluate the fungal isolates' rhizosphere competence, with the emphasis on the persistence of the original inoculum on the growing roots, (iii) to assess possible endophytic plant tissue colonization, and (iv) to evaluate potential plant growth stimulating effects of the added inoculi. Significant pathogenicity of tested fungi against Delia radicum was confirmed in in vitro and glasshouse experiments. All tested fungi persisted on cauliflower rhizoplane. More importantly, the added fungi were found on thoroughly washed roots outside the original point of inoculation. This provided us with evidence that our tested fungi could be transferred via or grow with the elongating roots. In addition to colonizing the rhizoplane, some fungi were found inside the plant root or stem tissue, thus exhibiting endophytic characteristics. The importance of fungal ecology as a criterion in appropriate biological control agent selection is discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

Control of Wilt and Rot Pathogens of Tomato by Antagonistic Pink Pigmented Facultative Methylotrophic Delftia lacustris and Bacillus spp.

PubMed

Janahiraman, Veeranan; Anandham, Rangasamy; Kwon, Soon W; Sundaram, Subbiah; Karthik Pandi, Veeranan; Krishnamoorthy, Ramasamy; Kim, Kiyoon; Samaddar, Sandipan; Sa, Tongmin

2016-01-01

The studies on the biocontrol potential of pink pigmented facultative methylotrophic (PPFM) bacteria other than the genus Methylobacterium are scarce. In the present study, we report three facultative methylotrophic isolates; PPO-1, PPT-1, and PPB-1, respectively, identified as Delftia lacustris, Bacillus subtilis , and Bacillus cereus by 16S rRNA gene sequence analysis. Hemolytic activity was tested to investigate the potential pathogenicity of isolates to plants and humans, the results indicates that the isolates PPO-1, PPT-1, and PPB-1 are not pathogenic strains. Under in vitro conditions, D. lacustris PPO-1, B . subtilis PPT-1, and B . cereus PPB-1 showed direct antagonistic effect by inhibiting the mycelial growth of fungal pathogens; Fusarium oxysporum f. sp. lycopersici (2.15, 2.05, and 1.95 cm), Sclerotium rolfsii (2.14, 2.04, and 1.94 cm), Pythium ultimum (2.12, 2.02, and 1.92 cm), and Rhizoctonia solani (2.18, 2.08, and 1.98 cm) and also produced volatile inhibitory compounds. Under plant growth chamber condition methylotrophic bacterial isolates; D . lacustris PPO-1, B . subtilis PPT-1, and B. cereus PPB-1 significantly reduced the disease incidence of tomato. Under greenhouse condition, D . lacustris PPO-1, B . subtilis PPT-1, and B . cereus PPB-1 inoculated tomato plants, when challenged with F . oxysporum f. sp. lycopersici, S . rolfsii, P . ultimum , and R . solani , increased the pathogenesis related proteins (β-1,3-glucanase and chitinase) and defense enzymes (phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and catalase) on day 5 after inoculation. In the current study, we first report the facultative methylotrophy in pink pigmented D. lacustris, B . subtilis , and B . cereus and their antagonistic potential against fungal pathogens. Direct antagonistic and ISR effects of these isolates against fungal pathogens of tomato evidenced their possible use as a biocontrol agent.

Control of Wilt and Rot Pathogens of Tomato by Antagonistic Pink Pigmented Facultative Methylotrophic Delftia lacustris and Bacillus spp.

PubMed Central

Janahiraman, Veeranan; Anandham, Rangasamy; Kwon, Soon W.; Sundaram, Subbiah; Karthik Pandi, Veeranan; Krishnamoorthy, Ramasamy; Kim, Kiyoon; Samaddar, Sandipan; Sa, Tongmin

2016-01-01

The studies on the biocontrol potential of pink pigmented facultative methylotrophic (PPFM) bacteria other than the genus Methylobacterium are scarce. In the present study, we report three facultative methylotrophic isolates; PPO-1, PPT-1, and PPB-1, respectively, identified as Delftia lacustris, Bacillus subtilis, and Bacillus cereus by 16S rRNA gene sequence analysis. Hemolytic activity was tested to investigate the potential pathogenicity of isolates to plants and humans, the results indicates that the isolates PPO-1, PPT-1, and PPB-1 are not pathogenic strains. Under in vitro conditions, D. lacustris PPO-1, B. subtilis PPT-1, and B. cereus PPB-1 showed direct antagonistic effect by inhibiting the mycelial growth of fungal pathogens; Fusarium oxysporum f. sp. lycopersici (2.15, 2.05, and 1.95 cm), Sclerotium rolfsii (2.14, 2.04, and 1.94 cm), Pythium ultimum (2.12, 2.02, and 1.92 cm), and Rhizoctonia solani (2.18, 2.08, and 1.98 cm) and also produced volatile inhibitory compounds. Under plant growth chamber condition methylotrophic bacterial isolates; D. lacustris PPO-1, B. subtilis PPT-1, and B. cereus PPB-1 significantly reduced the disease incidence of tomato. Under greenhouse condition, D. lacustris PPO-1, B. subtilis PPT-1, and B. cereus PPB-1 inoculated tomato plants, when challenged with F. oxysporum f. sp. lycopersici, S. rolfsii, P. ultimum, and R. solani, increased the pathogenesis related proteins (β-1,3-glucanase and chitinase) and defense enzymes (phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and catalase) on day 5 after inoculation. In the current study, we first report the facultative methylotrophy in pink pigmented D. lacustris, B. subtilis, and B. cereus and their antagonistic potential against fungal pathogens. Direct antagonistic and ISR effects of these isolates against fungal pathogens of tomato evidenced their possible use as a biocontrol agent. PMID:27872630

Cucumber rhizosphere microbial community response to biocontrol agent Bacillus subtilis B068150

USDA-ARS?s Scientific Manuscript database

Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum f. sp. Cucumerinum. However, their survival ability in cucumber rhizosphere and non-rhizosphere as well as their influence on native microbial communities has not been fully i...

Dragonflies are biocontrol agents in Wisconsin cranberry marshes

USDA-ARS?s Scientific Manuscript database

Dragonflies (Order Odonata) are abundant predators that emerge in large hatch events each summer in Wisconsin cranberry marshes. They seem to be a potential group of biocontrol agents for pest management that may be influenced by the diversity found on the marsh. In fact, our evidence shows that dra...

What magnitude are observed non-target impacts from weed biocontrol?

USDA-ARS?s Scientific Manuscript database

A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a ...

Identification of Putative Coffee Rust Mycoparasites via Single-Molecule DNA Sequencing of Infected Pustules.

PubMed

James, Timothy Y; Marino, John A; Perfecto, Ivette; Vandermeer, John

2016-01-15

The interaction of crop pests with their natural enemies is a fundament to their control. Natural enemies of fungal pathogens of crops are poorly known relative to those of insect pests, despite the diversity of fungal pathogens and their economic importance. Currently, many regions across Latin America are experiencing unprecedented epidemics of coffee rust (Hemileia vastatrix). Identification of natural enemies of coffee rust could aid in developing management strategies or in pinpointing species that could be used for biocontrol. In the present study, we characterized fungal communities associated with coffee rust lesions by single-molecule DNA sequencing of fungal rRNA gene bar codes from leaf discs (≈28 mm(2)) containing rust lesions and control discs with no rust lesions. The leaf disc communities were hyperdiverse in terms of fungi, with up to 69 operational taxonomic units (putative species) per control disc, and the diversity was only slightly reduced in rust-infected discs, with up to 63 putative species. However, geography had a greater influence on the fungal community than whether the disc was infected by coffee rust. Through comparisons between control and rust-infected leaf discs, as well as taxonomic criteria, we identified 15 putative mycoparasitic fungi. These fungi are concentrated in the fungal family Cordycipitaceae and the order Tremellales. These data emphasize the complexity of diverse fungi of unknown ecological function within a leaf that might influence plant disease epidemics or lead to the development of species for biocontrol of fungal disease. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Role of 2-hexyl, 5-propyl resorcinol production by Pseudomonas chlororaphis PCL1606 in the multitrophic interactions in the avocado rhizosphere during the biocontrol process.

PubMed

Calderón, Claudia E; de Vicente, Antonio; Cazorla, Francisco M

2014-07-01

Different bacterial traits can contribute to the biocontrol of soilborne phytopathogenic fungus. Among others, (1) antagonism, (2) competition for nutrients and niches, (3) induction of systemic resistance of the plants and (4) predation and parasitism are the most studied. Pseudomonas chlororaphis PCL1606 is an antagonistic rhizobacterium that produces the antifungal metabolite 2-hexyl, 5-propyl resorcinol (HPR). This bacterium can biologically control the avocado white root rot caused by Rosellinia necatrix. Confocal laser scanning microscopy of the avocado rhizosphere revealed that this biocontrol bacterium and the fungal pathogen compete for the same niche and presumably also for root exudate nutrients. The use of derivative mutants in the geners related to HPR biosynthesis (dar genes) revealed that the lack of HPR production by P. chlororaphis PCL1606 negatively influences the bacterial colonisation of the avocado root surface. Microscopical analysis showed that P. chlororaphis PCL1606 closely interacts and colonises the fungal hyphae, which may represent a novel biocontrol mechanism in this pseudomonad. Additionally, the presence of HPR-producing biocontrol bacteria negatively affects the ability of the fungi to infect the avocado root. HPR production negatively affects hyphal growth, leading to alterations in the R. necatrix physiology visible under microscopy, including the curling, vacuolisation and branching of hyphae, which presumably affects the colonisation and infection abilities of the fungus. This study provides the first report of multitrophic interactions in the avocado rhizosphere, advancing our understanding of the role of HPR production in those interactions. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62

USDA-ARS?s Scientific Manuscript database

Foliar biocontrol agent (BCA) efficacy is often inconsistent due to poor colonization and survival on plant surfaces. Burkholderia pyrrocinia FP62, a superior leaf colonist and BCA of Botrytis cinerea, forms unsaturated biofilms on plant surfaces. To determine the relationship between biocontrol act...

Identification and characterization of a new Bacillus atrophaeus strain B5 as biocontrol agent of postharvest anthracnose disease in soursop (Annona muricata) and avocado (Persea americana).

PubMed

Guardado-Valdivia, Lizeth; Tovar-Pérez, Erik; Chacón-López, Alejandra; López-García, Ulises; Gutiérrez-Martínez, Porfirio; Stoll, Alexandra; Aguilera, Selene

2018-05-01

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous fruit, including soursop and avocado. The use of fungicides to maintain the high quality of fruit creates a potential health risk. One alternative to this problem is the biological control, which has been applied successfully during postharvest. The Bacillus species are one of the most studied biological agents against postharvest pathogens because accomplish their biocontrol performance by producing a variety of metabolites. In this study, we evaluated the activity of metabolites contained in the cell free supernatant, obtained from Bacillus strain B5 culture, against micelial growth and spore germination of two virulent strains of C. gloeosporioides isolated from soursop and avocado. On the basis of 16S rDNA gene sequence analysis, this strain was identified as Bacillus atrophaeus. A preventive treatment using cell free supernatant, reduced severity and incidence of anthracnose disease on harvested soursop and avocado fruit. B. atrophaeus strain B5 harbors genes involved in the production of antibiotics such as surfactin, bacillomycin and iturin, which could be contributing to the efficiency of the preventive treatment during postharvest. The antagonistic role of metabolites contained in the cell free supernatant against anthracnose disease, provide a new approach by which to attack this problem and can help reduce the use of chemical pesticides, environmental pollution, leading to the safer fruit preservation. Copyright © 2018 Elsevier GmbH. All rights reserved.

Characterization of Novel Trichoderma asperellum Isolates to Select Effective Biocontrol Agents Against Tomato Fusarium Wilt

PubMed Central

El_Komy, Mahmoud H.; Saleh, Amgad A.; Eranthodi, Anas; Molan, Younes Y.

2015-01-01

The use of novel isolates of Trichoderma with efficient antagonistic capacity against Fusarium oxysporum f. sp. lycopersici (FOL) is a promising alternative strategy to pesticides for tomato wilt management. We evaluated the antagonistic activity of 30 isolates of T. asperellum against 4 different isolates of FOL. The production of extracellular cell wall degrading enzymes of the antagonistic isolates was also measured. The random amplified polymorphic DNA (RAPD) method was applied to assess the genetic variability among the T. asperellum isolates. All of the T. asperellum isolates significantly reduced the mycelial growth of FOL isolates but the amount of growth reduction varied significantly as well. There was a correlation between the antagonistic capacity of T. asperellum isolates towards FOL and their lytic enzyme production. Isolates showing high levels of chitinase and β-1,3-glucanase activities strongly inhibited the growth of FOL isolates. RAPD analysis showed a high level of genetic variation among T. asperellum isolates. The UPGMA dendrogram revealed that T. asperellum isolates could not be grouped by their anta- gonistic behavior or lytic enzymes production. Six isolates of T. asperellum were highly antagonistic towards FOL and potentially could be used in commercial agriculture to control tomato wilt. Our results are consistent with the conclusion that understanding the genetic variation within Trichoderma isolates and their biochemical capabilities are required for the selection of effective indigenous fungal strains for the use as biocontrol agents. PMID:25774110

Pathogenic differences of the entomopathogenic fungus Isaria cateniannulata to the spider mite Tetranychus urticae (Trombidiformes: Tetranychidae) and its predator Euseius nicholsi (Mesostigmata: Phytoseiidae).

PubMed

Zhang, Xiao-Na; Guo, Jian-Jun; Zou, Xiao; Jin, Dao-Chao

2018-05-01

Isaria cateniannulata and Euseius nicholsi are two important biological control agents currently being used in many areas of China to control a variety of pests. In order to determine the possibility of a concomitant application with the two agents in a biocontrol program involving the two-spotted spider mite, Tetranychus urticae, we quantified the pathogenicity of a strain of I. cateniannulata (08XS-1) against females of both T. urticae and E. nicholsi. We observed the infection process using scanning electron microscopy and fluorescence microscopy to distinguish differences in fungal performance. The female mites were infected by I. cateniannulata at 2 × 10 7 conidia/ml. The mortality of T. urticae was 100% when treated with submerged conidia and 92% when treated with aerial conidia (spray), and that of E. nicholsi was 4.2 and 6.7%, correspondingly. Following infection with aerial or submerged conidia, mated E. nicholsi females displayed no significant differences between treatments and control, indicating the fungus had no obvious effect on their vitality and fertility. This demonstrates that I. cateniannulata is safe to E. nicholsi when used to control T. urticae. The two types of propagules of I. cateniannulata are readily produced by common culture, and the submerged conidia, because of their substantially higher mortality, are preferable to the aerial conidia. Our results indicate that I. cateniannulata and E. nicholsi are viable candidates to be concomitantly applied in the biocontrol programs of T. urticae.

Pathogenicity of Three Entomopathogenic Fungi to Matsucoccus matsumurae

PubMed Central

Liu, Weimin; Xie, Yingping; Dong, Jing; Xue, Jiaoliang; Zhang, Yanfeng; Lu, Yaobin; Wu, Jun

2014-01-01

Matsucoccus matsumurae (Kuwana) (Hemiptera: Coccoidea: Matsucoccidae) is an invasive alien species and a destructive pest of two native Chinese pines, Pinus tabulaeformis Carr. and P. massoniana Lamb., throughout the eastern regions of China. The pathogenicity of three entomopathogenic fungi, Lecanicillium lecanii strain V3.4504 and V3.4505, Fusarium incarnatum-equiseti strain HEB01 and Lecanicillium fungicola strain HEB02, against M. matsumurae was tested in four instars, to evaluate their potential as a biological control agent. The results showed that the four strains caused disease and death of the scale insect, among which the L. lecanii strains V3.4504 and V3.4505 displayed stronger virulence than the F. incarnatum-equiseti strains HEB01 and L. fungicola strain HEB02 to M. matsumurae in the 2nd-instar nymphs and the adult females. Furthermore, L. lecanii V3.4505 was most virulent to M. matsumurae. The adult females and the male 3rd-instar nymphs of M. matsumurae were susceptible to L. lecanii V3.4505; the adult females were more susceptible at LT50 = 1.96 than the 3rd-instar nymphs at LT50 = 5.67. The body surface structure, cuticle thickness and wax secretions of M. matsumurae impacted the fungal infection. L. lecanii is a promising biocontrol agent, and newly emerged male 3rd-instar nymphs and adult females are a crucial period of the insect’s life cycle for M. matsumurae biocontrol. PMID:25068397

Pathogenicity of three entomopathogenic fungi to Matsucoccus matsumurae.

PubMed

Liu, Weimin; Xie, Yingping; Dong, Jing; Xue, Jiaoliang; Zhang, Yanfeng; Lu, Yaobin; Wu, Jun

2014-01-01

Matsucoccus matsumurae (Kuwana) (Hemiptera: Coccoidea: Matsucoccidae) is an invasive alien species and a destructive pest of two native Chinese pines, Pinus tabulaeformis Carr. and P. massoniana Lamb., throughout the eastern regions of China. The pathogenicity of three entomopathogenic fungi, Lecanicillium lecanii strain V3.4504 and V3.4505, Fusarium incarnatum-equiseti strain HEB01 and Lecanicillium fungicola strain HEB02, against M. matsumurae was tested in four instars, to evaluate their potential as a biological control agent. The results showed that the four strains caused disease and death of the scale insect, among which the L. lecanii strains V3.4504 and V3.4505 displayed stronger virulence than the F. incarnatum-equiseti strains HEB01 and L. fungicola strain HEB02 to M. matsumurae in the 2nd-instar nymphs and the adult females. Furthermore, L. lecanii V3.4505 was most virulent to M. matsumurae. The adult females and the male 3rd-instar nymphs of M. matsumurae were susceptible to L. lecanii V3.4505; the adult females were more susceptible at LT50 = 1.96 than the 3rd-instar nymphs at LT50 = 5.67. The body surface structure, cuticle thickness and wax secretions of M. matsumurae impacted the fungal infection. L. lecanii is a promising biocontrol agent, and newly emerged male 3rd-instar nymphs and adult females are a crucial period of the insect's life cycle for M. matsumurae biocontrol.

Isolation and Evaluation of New Antagonist Bacillus Strains for the Control of Pathogenic and Mycotoxigenic Fungi of Fig Orchards.

PubMed

Öztopuz, Özlem; Pekin, Gülseren; Park, Ro Dong; Eltem, Rengin

2018-05-03

Bacillus is an antagonistic bacteria that shows high effectiveness against different phytopathogenic fungi and produces various lytic enzymes, such as chitosanase, chitinase, protease, and gluconase. The aim of this study is to determine Bacillus spp. for lytic enzyme production and to evaluate the antifungal effects of the selected strains for biocontrol of mycotoxigenic and phytopathogenic fungi. A total of 92 endospore-forming bacterial isolates from the 24 fig orchard soil samples were screened for chitosanase production, and six best chitosanolytic isolates were selected to determine chitinase, protease, and N-acetyl-β-hexosaminidase activity and molecularly identified. The antagonistic activities of six Bacillus strains against Aspergillus niger EGE-K-213, Aspergillus foetidus EGE-K-211, Aspergillus ochraceus EGE-K-217, and Fusarium solani KCTC 6328 were evaluated. Fungal spore germination inhibition and biomass inhibition activities were also measured against A. niger EGE-K-213. The results demonstrated that Bacillus mojavensis EGE-B-5.2i and Bacillus thuringiensis EGE-B-14.1i were more efficient antifungal agents against A. niger EGE-K-213. B. mojavensis EGE-B-5.2i has shown maximum inhibition of the biomass (30.4%), and B. thuringiensis EGE-B-14.1i has shown maximum inhibition of spore germination (33.1%) at 12 h. This is the first study reporting the potential of antagonist Bacillus strains as biocontrol agents against mycotoxigenic fungi of fig orchads.

Tolerance of triazole-based fungicides by biocontrol agents used to control Fusarium head blight in wheat in Argentina.

PubMed

Palazzini, J M; Torres, A M; Chulze, S N

2018-05-01

Fusarium head blight (FHB) caused by Fusarium graminearum species complex is a devastating disease that causes extensive yield and quality losses to wheat around the world. Fungicide application and breeding for resistance are among the most important tools to counteract FHB. Biological control is an additional tool that can be used as part of an integrated management of FHB. Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B were selected by their potential to control FHB and deoxynivalenol production. The aim of this work was to test the tolerance of these biocontrol agents to triazole-based fungicides such as prothioconazole, tebuconazole and metconazole. Bacterial growth was evaluated in Petri dishes using the spread plating technique containing the different fungicides. Bacillus velezensisRC 218 and Streptomyces sp. RC 87B showed better tolerance to fungicides than Brevibacillus sp. RC 263. Complete growth inhibition was observed at concentrations of 20 μg ml -1 for metconazole, 40 μg ml -1 for tebuconazole and 80 μg ml -1 for prothioconazole. The results obtained indicate the possibility of using these biocontrol agents in combination with fungicides as part of an integrated management to control FHB of wheat. This study evaluates the possibility to use biocontrol agents (Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B) in combination with triazole-based fungicides to control Fusarium head blight in wheat. The evaluation of biocontrol agents' growth under in vitro conditions was carried out in Petri dishes containing either prothioconazole, tebuconazole or metconazole. Viability studies demonstrated that B. velezensisRC 218 and Streptomyces sp. RC 87B were more tolerant to the fungicides evaluated. Results obtained reflect the possibility to use fungicides at low doses combined with biocontrol agents. © 2018 The Society for Applied Microbiology.

Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation

PubMed Central

Lemos Junior, Wilson José Fernandes; Bovo, Barbara; Nadai, Chiara; Crosato, Giulia; Carlot, Milena; Favaron, Francesco; Giacomini, Alessio; Corich, Viviana

2016-01-01

Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying antifungal activity. Thirty-six isolates were identified as Starmerella bacillaris, a species recently proven to be of enological interest. Among them 14 different strains were studied and antifungal activity against B. cinerea was demonstrated, for the first time, to be present in S. bacillaris species. The production of volatile organic compounds (VOCs), tested in vitro, was found to be the main responsible of S. bacillaris antifungal effects. All the strains were able to reduce B. cinerea decay on wounded grape berries artificially inoculated with gray mold. The colonization level of wound was very high reaching, after 5 days, a concentration of 106 cells per ml of grape juice obtained after berry crushing. At this cell concentration S. bacillaris strains were used to ferment synthetic and natural musts. The sequential yeast inoculation, performed by adding S. cerevisiae 48 h after S. bacillaris, was needed to complete sugar consumption and determined a significant increase in glicerol content and a reduction of ethanol and acetic acid concentrations. The high wound colonization ability, found in this work, together with the propensity to colonize grape berry and the interesting enological traits possessed by the selected S. bacillaris strains allow the use of this yeast as biocontrol agent on vine and grape berries with possible positive effects on must fermentation, although the presence of S. cerevisiae is needed to complete the fermentation process. This work introduces new possibilities in wine yeast selection programs in order to identify innovative wine yeasts that are simultaneously antifungal agents in vineyards and alternative wine starters for grape must fermentation and open new perspective to a more integrated strategy for increasing wine quality. PMID:27574517

Response to Thomas et al.: Biocontrol and indirect effects

Treesearch

Dean E. Pearson; Ragan M. Callaway

2004-01-01

In a recent TREE article [1], we identified three categories of unintended indirect effects that can arise from host-specific biological control agents: (i) ecological replacement; (ii) compensatory responses; and (iii) food-web interactions. Although our review focused on the biocontrol of plant pests, we suggested these concepts also apply to the biocontrol...

Plot- and landscape-level changes in climate and vegetation following defoliation of exotic saltcedar (Tamarix sp.) from the biocontrol agent Diorhabda carinulata along a stream in the Mojave Desert (USA)

USGS Publications Warehouse

Bateman, H.L.; Nagler, P.L.; Glenn, E.P.

2013-01-01

The biocontrol agent, northern tamarisk beetle (Diorhabda carinulata), has been used to defoliate non-native saltcedar (Tamarix spp.) in USA western riparian systems since 2001. Biocontrol has the potential to impact biotic communities and climatic conditions in affected riparian areas. To determine the relationships between biocontrol establishment and effects on vegetation and climate at the plot and landscape scales, we measured temperature, relative humidity, foliage canopy, solar radiation, and used satellite imagery to assess saltcedar defoliation and evapotranspiration (ET) along the Virgin River in the Mojave Desert. Following defoliation solar radiation increased, daily humidity decreased, and maximum daily temperatures tended to increase. MODIS and Landsat satellite imagery showed defoliation was widespread, resulting in reductions in ET and vegetation indices. Because biocontrol beetles are spreading into new saltcedar habitats on arid western rivers, and the eventual equilibrium between beetles and saltcedar is unknown, it is necessary to monitor trends for ecosystem functions and higher trophic-level responses in habitats impacted by biocontrol.

Exploiting the behaviour of wild malaria vectors to achieve high infection with fungal biocontrol agents

PubMed Central

2012-01-01

Background Control of mosquitoes that transmit malaria has been the mainstay in the fight against the disease, but alternative methods are required in view of emerging insecticide resistance. Entomopathogenic fungi are candidate alternatives, but to date, few trials have translated the use of these agents to field-based evaluations of their actual impact on mosquito survival and malaria risk. Mineral oil-formulations of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were applied using five different techniques that each exploited the behaviour of malaria mosquitoes when entering, host-seeking or resting in experimental huts in a malaria endemic area of rural Tanzania. Results Survival of mosquitoes was reduced by 39-57% relative to controls after forcing upward house-entry of mosquitoes through fungus treated baffles attached to the eaves or after application of fungus-treated surfaces around an occupied bed net (bed net strip design). Moreover, 68 to 76% of the treatment mosquitoes showed fungal growth and thus had sufficient contact with fungus treated surfaces. A population dynamic model of malaria-mosquito interactions shows that these infection rates reduce malaria transmission by 75-80% due to the effect of fungal infection on adult mortality alone. The model also demonstrated that even if a high proportion of the mosquitoes exhibits outdoor biting behaviour, malaria transmission was still significantly reduced. Conclusions Entomopathogenic fungi strongly affect mosquito survival and have a high predicted impact on malaria transmission. These entomopathogens represent a viable alternative for malaria control, especially if they are used as part of an integrated vector management strategy. PMID:22449130

Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus x domestica)

USDA-ARS?s Scientific Manuscript database

Psychrotrophic yeasts isolated from soils collected in Antarctica and selected by its capacity of growing in apple juice at low temperatures were evaluated for their potential as biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, ...

Broad-spectrum inhibition of Phytophthora infestans by fungal endophytes

PubMed Central

von Dahlen, Janina K; Schnake, Anika; Ginschel, Sarah; Schulz, Barbara; Rose, Laura E

2018-01-01

ABSTRACT Phytophthora infestans is a devastating pathogen of tomato and potato. It readily overcomes resistance genes and applied agrochemicals and hence even today causes large yield losses. Fungal endophytes provide a largely unexplored avenue of control of Phy. infestans. Not only do endophytes produce a wide array of bioactive metabolites, they may also directly compete with and defeat pathogens in planta. Here, we tested 12 fungal endophytes isolated from different plant species in vitro for their production of metabolites with anti- Phytophthora activity. Four well-performing isolates were evaluated for their ability to suppress nine isolates of Phy. infestans on agar medium and in planta. Two endophytes reliably inhibited all Phy. infestans isolates on agar medium, of which Phoma eupatorii isolate 8082 was the most promising. It nearly abolished infection by Phy. infestans in planta. Our data indicate a role for the production of anti-Phytophthora compounds by the fungus and/or an enhanced plant defense response, as evident by an enhanced anthocyanin production. Here, we present a potential biocontrol agent, which can inhibit a broad-spectrum of Phy. infestans isolates. Such broadly acting inhibition is ideal, because it allows for effective control of genetically diverse isolates and may slow the adaptation of Phy. infestans. PMID:29528408

Seed treatments to control seedborne fungal pathogens of vegetable crops.

PubMed

Mancini, Valeria; Romanazzi, Gianfranco

2014-06-01

Vegetable crops are frequently infected by fungal pathogens, which can include seedborne fungi. In such cases, the pathogen is already present within or on the seed surface, and can thus cause seed rot and seedling damping-off. Treatment of vegetable seeds has been shown to prevent plant disease epidemics caused by seedborne fungal pathogens. Furthermore, seed treatments can be useful in reducing the amounts of pesticides required to manage a disease, because effective seed treatments can eliminate the need for foliar application of fungicides later in the season. Although the application of fungicides is almost always effective, their non-target environmental impact and the development of pathogen resistance have led to the search for alternative methods, especially in the past few years. Physical treatments that have already been used in the past and treatments with biopesticides, such as plant extracts, natural compounds and biocontrol agents, have proved to be effective in controlling seedborne pathogens. These have been applied alone or in combination, and they are widely used owing to their broad spectrum in terms of disease control and production yield. In this review, the effectiveness of different seed treatments against the main seedborne pathogens of some important vegetable crops is critically discussed. © 2013 Society of Chemical Industry.

Experimental evolution to increase the efficacy of the entomopathogenic fungus Beauveria bassiana against malaria mosquitoes: Effects on mycelial growth and virulence.

PubMed

Valero-Jiménez, Claudio A; van Kan, Jan A L; Koenraadt, Constantianus J M; Zwaan, Bas J; Schoustra, Sijmen E

2017-06-01

Entomopathogenic fungi such as Beauveria bassiana are currently considered as a potential control agent for malaria mosquitoes. The success of such strategies depends among others on the efficacy of the fungus to kill its hosts. As B. bassiana can use various resources for growth and reproduction, increasing the dependency on mosquitoes as a nutritional source may be instrumental for reaching this goal. Passage of entomopathogenic fungi through an insect host has been shown to increase its virulence. We evaluated the virulence, fungal outgrowth, mycelial growth rate, and sporulation rate of two B. bassiana isolates (Bb1520 and Bb8028) that underwent 10 consecutive selection cycles through malaria mosquitoes ( Anopheles coluzzii ) using an experimental evolution approach. This cycling resulted in an altered capacity of evolved B. Bassiana lineages to grow on different substrates while maintaining the ability to kill insects. Notably, however, there were no significant changes in virulence or speed of outgrowth when comparing the evolved lineages against their unevolved ancestors. These results suggest that fungal growth and sporulation evolved through successive and exclusive use of an insect host as a nutritional resource. We discuss the results in light of biocontrol and provide suggestions to increase fungal virulence.

Chestnut green waste composting for sustainable forest management: Microbiota dynamics and impact on plant disease control.

PubMed

Ventorino, Valeria; Parillo, Rita; Testa, Antonino; Viscardi, Sharon; Espresso, Francesco; Pepe, Olimpia

2016-01-15

Making compost from chestnut lignocellulosic waste is a possible sustainable management strategy for forests that employs a high-quality renewable organic resource. Characterization of the microbiota involved in composting is essential to better understand the entire process as well as the properties of the final product. Therefore, this study investigated the microbial communities involved in the composting of chestnut residues obtained from tree cleaning and pruning. The culture-independent approach taken highlighted the fact that the microbiota varied only slightly during the process, with the exception of those of the starting substrate and mature compost. The statistical analysis indicated that most of the bacterial and fungal species in the chestnut compost persisted during composting. The dominant microbial population detected during the process belonged to genera known to degrade recalcitrant lignocellulosic materials. Specifically, we identified fungal genera, such as Penicillium, Fusarium, Cladosporium, Aspergillus and Mucor, and prokaryotic species affiliated with Bacilli, Actinobacteria, Flavobacteria and γ-Proteobacteria. The suppressive properties of compost supplements for the biocontrol of Sclerotinia minor and Rhizoctonia solani were also investigated. Compared to pure substrate, the addition of compost to the peat-based growth substrates resulted in a significant reduction of disease in tomato plants of up to 70 % or 51 % in the presence of Sclerotinia minor or Rhizoctonia solani, respectively. The obtained results were related to the presence of putative bio-control agents and plant growth-promoting rhizobacteria belonging to the genera Azotobacter, Pseudomonas, Stenotrophomonas, Bacillus, Flavobacterium, Streptomyces and Actinomyces in the chestnut compost. The composting of chestnut waste may represent a sustainable agricultural practice for disposing of lignocellulosic waste by transforming it into green waste compost that can be used to improve the fitness of agricultural plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential of endophytic fungi as biocontrol agents of Duponchelia fovealis (Zeller) (Lepidoptera:Crambidae).

PubMed

Amatuzzi, R F; Cardoso, N; Poltronieri, A S; Poitevin, C G; Dalzoto, P; Zawadeneak, M A; Pimentel, I C

2017-11-09

This study reports the first assessment of endophytic fungi isolated from strawberry leaves and selection of isolates for the control of Duponchelia fovealis, a new pest of strawberries. A total of 400 strawberry leaves of the cultivar 'Albion' were collected in four commercial farms. Leaves were disinfected, cut in fragments, and placed on Petri dishes containing potato dextrose agar media with tetracycline and incubated for 30 days. Following this time, 517 fungal colonies were isolated, and thirteen genera were identified: Cladosporium, Aspergillus, Nigrospora, Fusarium, Trichoderma, Chaetomium, Alternaria, Paecilomyces, Penicillium, Ulocladium, Bipolaris, Diaporthe, and Phoma. Eight isolates belonging to the genera Aspergillus, Diaporthe, Paecilomyces, and Cladosporium were selected for pathogenicity bioassays against third instar larvae of D. fovealis. Isolates of Paecilomyces induced the highest mortality rates.

Endemic plants harbour specific Trichoderma communities with an exceptional potential for biocontrol of phytopathogens.

PubMed

Zachow, Christin; Berg, Christian; Müller, Henry; Monk, Jana; Berg, Gabriele

2016-10-10

Trichoderma strains exhibit enormous potential for applications in biotechnology, in particular as biocontrol agents against pathogens. However, little is known about the diversity of plant-associated Trichoderma communities at a global scale and their antagonistic spectrum. In order to gather information about structure and function, we compared Trichoderma biomes of endemic (Aeonium, Diospyros, Hebe, Rhododendron) and cosmopolitan plants (Zea mays) in a global study encompassing the area Northwest Africa to New Zealand via the European Alps and Madagascar. At the quantitative level we found no differences between cosmopolitan and endemic plants. Statistically significant differences were detected at the qualitative level: Trichoderma populations of endemic plants were highly specific and diverse with hot spots appearing in Madagascar and New Zealand. By contrast, maize plants from all sites shared the majority of Trichoderma species (65.5%). Interestingly, the high above ground biodiversity in ecosystems containing endemic plants was confirmed by a high below ground Trichoderma diversity. Despite the differences, we found a global Trichoderma core community shared by all analysed plants, which was dominated by T. koningii and T. koningiopsis. Amplicon-based network analyses revealed a high similarity between maize Trichoderma grown world-wide and distinct populations of endemic plants. Furthermore, Trichoderma strains from endemic plants showed a higher antagonistic activity against fungal pathogens compared to maize-associated strains. Our results showed that endemic plants are associated with a specific Trichoderma microbiome which possesses a high antagonistic activity indicating that it has potential to be used for biocontrol purposes. Copyright © 2016 Elsevier B.V. All rights reserved.

Microscopic Examination of Chitosan Polyphosphate Beads with Entrapped Spores of the Biocontrol Agent, Streptomyces melanosporofaciens EF-76

NASA Astrophysics Data System (ADS)

Jobin, Guy; Grondin, Gilles; Couture, Geneviève; Beaulieu, Carole

2005-04-01

Spores of the biocontrol agent, Streptomyces melanosporofaciens EF-76, were entrapped by complex coacervation in beads composed of a macromolecular complex (MC) of chitosan and polyphosphate. A proportion of spores entrapped in beads survived the entrapment procedure as shown by treating spores from chitosan beads with a dye allowing the differentiation of live and dead cells. The spore-loaded chitosan beads could be digested by a chitosanase, suggesting that, once introduced in soil, the beads would be degraded to release the biocontrol agent. Spore-loaded beads were examined by optical and scanning electron microscopy because the release of the biological agent depends on the spore distribution in the chitosan beads. The microscopic examination revealed that the beads had a porous surface and contained a network of inner microfibrils. Spores were entrapped in both the chitosan microfibrils and the bead lacuna.

Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus × domestica).

PubMed

Vero, Silvana; Garmendia, Gabriela; González, M Belén; Bentancur, Oscar; Wisniewski, Michael

2013-03-01

Psychrotrophic yeasts were isolated from Antarctic soils, selected based on their ability to grow in apple juice at low temperatures, and were evaluated as potential biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, an isolate of Leucosporidium scottii, designated At17, was identified as a good biocontrol agent for blue and gray mold of two apple cultivars. The selected isolate produced soluble and volatile antifungal substances that were inhibitory to apple pathogens. Siderophore production was also demonstrated, but it did not appear to play a role in pathogen inhibition. The selected yeast had the capacity to form a biofilm when grown in apple juice, which is considered an important attribute of postharvest antagonists to successfully colonize wounds and intact fruit surfaces. At17 was resistant to commonly used postharvest fungicides, so application of a combination of low-dose fungicide along with the biocontrol agent could be used as an integrated management practice. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Mycotoxigenic Fusarium and Deoxynivalenol Production Repress Chitinase Gene Expression in the Biocontrol Agent Trichoderma atroviride P1

PubMed Central

Lutz, Matthias P.; Feichtinger, Georg; Défago, Geneviève; Duffy, Brion

2003-01-01

Mycotoxin contamination associated with head blight of wheat and other grains caused by Fusarium culmorum and F. graminearum is a chronic threat to crop, human, and animal health throughout the world. One of the most important toxins in terms of human exposure is deoxynivalenol (DON) (formerly called vomitoxin), an inhibitor of protein synthesis with a broad spectrum of toxigenicity against animals. Certain Fusarium toxins have additional antimicrobial activity, and the phytotoxin fusaric acid has recently been shown to modulate fungus-bacterium interactions that affect plant health (Duffy and Défago, Phytopathology 87:1250-1257, 1997). The potential impact of DON on Fusarium competition with other microorganisms has not been described previously. Any competitive advantage conferred by DON would complicate efforts to control Fusarium during its saprophytic growth on crop residues that are left after harvest and constitute the primary inoculum reservoir for outbreaks in subsequent plantings. We examined the effect of the DON mycotoxin on ecological interactions between pathogenic Fusarium and Trichoderma atroviride strain P1, a competitor fungus with biocontrol activity against a wide range of plant diseases. Expression of the Trichoderma chitinase genes, ech42 and nag1, which contribute to biocontrol activity, was monitored in vitro and on crop residues of two maize cultivars by using goxA reporter gene fusions. We found that DON-producing F. culmorum and F. graminearum strains repressed expression of nag1-gox. DON-negative wild-type Fusarium strains and a DON-negative mutant with an insertional disruption in the tricothecene biosynthetic gene, tri5, had no effect on antagonist gene expression. The role of DON as the principal repressor above other pathogen factors was confirmed. Exposure of Trichoderma to synthetic DON or to a non-DON-producing Fusarium mutant resulted in the same level of nag1-gox repression as the level observed with DON-producing Fusarium. DON repression was specific for nag1-gox and had no effect, either positive or negative, on expression of another key chitinase gene, ech42. This is the first demonstration that a target pathogen down-regulates genes in a fungal biocontrol agent, and our results provide evidence that mycotoxins have a novel ecological function as factors in Fusarium competitiveness. PMID:12788701

Unsuccessful introduced biocontrol agents can act as pollinators of invasive weeds: Bitou Bush (Chrysanthemoides monilifera ssp. rotundata) as an example.

PubMed

Gross, Caroline L; Whitehead, Joshua D; Silveira de Souza, Camila; Mackay, David

2017-10-01

The extent of self-compatibility and reliance on pollinators for seed set are critical determinants of reproductive success in invasive plant species. Seed herbivores are commonly used as biocontrol agents but may also act as flower visitors, potentially resulting in pollination. However, such contrasting or potentially counterproductive interaction effects are rarely considered or evaluated for biological control programs. We investigated the breeding system and pollinators of Bitou Bush ( Chrysanthemoides monilifera ssp. rotundata ), an invasive species in Australia that has been the subject of biocontrol programs since 1987. We found the species to be obligate outcrossing in all six populations tested. From 150 video hours, we found 21 species of potential pollinators, including Mesoclanis polana , the Bitou Seedfly, native to South Africa and released in Australia as a biocontrol agent in 1996. Mesoclanis polana transferred pollen to stigmas and was the most common pollinator (52% of pollinator visits), followed by the syrphid fly Simosyrphus grandicornis (9%) and introduced honeybee, Apis mellifera (6.5%). Fruit-to-flower ratios ranged from 0.12 to 0.45 and were highest in the population with the greatest proportion of Mesoclanis polana visits. In an experimental trial, outside the naturalized range, the native bee Homalictus sphecodoides and the native syrphid Melangyna viridiceps were the primary pollinators, and fruit-to-flower ratios were 0.35, indicating that Bitou Bush would have ready pollinators if its range expanded inland. Synthesis . Invasive Bitou Bush requires pollinators, and this is effected by a range of generalist pollinators in eastern Australia including the Bitou Seedfly, introduced as a biocontrol agent, and the major pollinator detected in this study. Fruit-to-flower ratios were highest when the Bitou Seedfly was in high abundance. This study underscores the importance of evaluating the pollination biology of invasive species in their native ranges and prior to the introduction of biocontrol agents.

RNA Interference of Endochitinases in the Sugarcane Endophyte Trichoderma virens 223 Reduces Its Fitness as a Biocontrol Agent of Pineapple Disease

PubMed Central

Romão-Dumaresq, Aline S.; de Araújo, Welington Luiz; Talbot, Nicholas J.; Thornton, Christopher R.

2012-01-01

The sugarcane root endophyte Trichoderma virens 223 holds enormous potential as a sustainable alternative to chemical pesticides in the control of sugarcane diseases. Its efficacy as a biocontrol agent is thought to be associated with its production of chitinase enzymes, including N-acetyl-ß-D-glucosaminidases, chitobiosidases and endochitinases. We used targeted gene deletion and RNA-dependent gene silencing strategies to disrupt N-acetyl-ß-D-glucosaminidase and endochitinase activities of the fungus, and to determine their roles in the biocontrol of soil-borne plant pathogens. The loss of N-acetyl-ß-D-glucosaminidase activities was dispensable for biocontrol of the plurivorous damping-off pathogens Rhizoctonia solani and Sclerotinia sclerotiorum, and of the sugarcane pathogen Ceratocystis paradoxa, the causal agent of pineapple disease. Similarly, suppression of endochitinase activities had no effect on R. solani and S. sclerotiorum disease control, but had a pronounced effect on the ability of T. virens 223 to control pineapple disease. Our work demonstrates a critical requirement for T. virens 223 endochitinase activity in the biocontrol of C. paradoxa sugarcane disease, but not for general antagonism of other soil pathogens. This may reflect its lifestyle as a sugarcane root endophyte. PMID:23110120

Combinations of biocontrol agents for management of plant-parasitic nematodes and soilborne plant-pathogenic fungi.

PubMed

Meyer, Susan L F; Roberts, Daniel P

2002-03-01

Numerous microbes are antagonistic to plant-parasitic nematodes and soilborne plant-pathogenic fungi, but few of these organisms are commercially available for management of these pathogens. Inconsistent performance of applied biocontrol agents has proven to be a primary obstacle to the development of successful commercial products. One of the strategies for overcoming inconsistent performance is to combine the disease-suppressive activity of two (or more) beneficial microbes in a biocontrol preparation. Such combinations have potential for more extensive colonization of the rhizosphere, more consistent expression of beneficial traits under a broad range of soil conditions, and antagonism to a larger number of plant pests or pathogens than strains applied individually. Conversely, microbes applied in combination also may have antagonistic interactions with each other. Increased, decreased, and unaltered suppression of the target pathogen or pest has been observed when biocontrol microbes have been applied in combination. Unfortunately, the ecological basis for increased or decreased suppression has not been determined in many cases and needs further consideration. The complexity of interactions involved in the application of multiple organisms for biological control has slowed progress toward development of successful formulations. However, this approach has potential for overcoming some of the efficacy problems that occur with application of individual biocontrol agents.

Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM223

PubMed Central

Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J.; Novinscak, Amy

2015-01-01

Pseudomonas fluorescens LBUM223 is a plant growth-promoting rhizobacterium (PGPR) with biocontrol activity against various plant pathogens. It produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of Streptomyces scabies, the causal agent of common scab of potato. Here, we report the complete genome sequence of P. fluorescens LBUM223. PMID:25953163

MaHog1, a Hog1-type mitogen-activated protein kinase gene, contributes to stress tolerance and virulence of the entomopathogenic fungus Metarhizium acridum.

PubMed

Jin, Kai; Ming, Yue; Xia, Yu Xian

2012-12-01

Fungal biocontrol agents have great potential in integrated pest management. However, poor efficacy and sensitivity to various adverse factors have hampered their wide application. In eukaryotic cells, Hog1 kinase plays a critical role in stress responses. In this study, MaHog1 (GenBank accession no. EFY85878), encoding a member of the Hog1/Sty1/p38 mitogen-activated protein kinase family in Metarhizium (Me.) acridum, was identified. Targeted gene disruption was used to analyse the role of MaHog1 in virulence and tolerance of adverse factors. Mutants with MaHog1 depletion showed increased sensitivity to high osmotic stress, high temperature and oxidative stress, and exhibited remarkable resistance to cell wall-disturbing agents. These results suggest that Hog1 kinase has a conserved function in regulating multistress responses among fungi, and that MaHog1 might influence cell wall biogenesis in Me. acridum. Bioassays conducted with topical inoculation and intrahaemocoel injection revealed that MaHog1 is required for both penetration and postpenetration development of Me. acridum. MaHog1 disruption resulted in a significant reduction in virulence, likely due to the combination of a decrease in conidial germination, a reduction in appressorium formation and a decline in growth rate in insect haemolymph, which might be caused by impairing fungal tolerance of various stresses during infection.

Non-aflatoxigenic Aspergillus flavus as potential biocontrol agents to reduce aflatoxin contamination in peanuts harvested in Northern Argentina.

PubMed

Alaniz Zanon, María Silvina; Barros, Germán Gustavo; Chulze, Sofía Noemí

2016-08-16

Biological control is one of the most promising strategies for preventing aflatoxin contamination in peanuts at field stage. A population of 46 native Aspergillus flavus nonaflatoxin producers were analysed based on phenotypic, physiological and genetic characteristics. Thirty-three isolates were characterized as L strain morphotype, 3 isolates as S strain morphotype, and 10 isolates did not produce sclerotia. Only 11 of 46 non-aflatoxigenic isolates did not produce cyclopiazonic acid. The vegetative compatibility group (VCG) diversity index for the population was 0.37. For field trials we selected the non-aflatoxigenic A. flavus AR27, AR100G and AFCHG2 strains. The efficacy of single and mixed inocula as potential biocontrol agents in Northern Argentina was evaluated through a 2-year study (2014-2015). During the 2014 peanut growing season, most of the treatments reduced the incidence of aflatoxigenic strains in both soil and peanut kernel samples, and no aflatoxin was detected in kernels. During the 2015 growing season, there was a reduction of aflatoxigenic strains in kernel samples from the plots treated with the potential biocontrol agents. Reductions of aflatoxin contamination between 78.36% and 89.55% were observed in treated plots in comparison with the un-inoculated control plots. This study provides the first data on aflatoxin biocontrol based on competitive exclusion in the peanut growing region of Northern Argentina, and proposes bioproducts with potential use as biocontrol agents. Copyright © 2016. Published by Elsevier B.V.

Analysis of Whitefly Transcriptional Responses to Beauveria bassiana Infection Reveals New Insights into Insect-Fungus Interactions

PubMed Central

Zhang, Shan; Li, Fang-Fang; Feng, Ming-Guang; Wang, Xiao-Wei; Liu, Shu-Sheng

2013-01-01

Background The fungal pathogen, Beauveria bassiana, is an efficient biocontrol agent against a variety of agricultural pests. A thorough understanding of the basic principles of insect-fungus interactions may enable the genetic modification of Beauveria bassiana to enhance its virulence. However, the molecular mechanism of insect response to Beauveria bassiana infection is poorly understood, let alone the identification of fungal virulent factors involved in pathogenesis. Methodology/Principal Findings Here, next generation sequencing technology was applied to examine the expression of whitefly (Bemisia tabaci) genes in response to the infection of Beauveria bassiana. Results showed that, compared to control, 654 and 1,681genes were differentially expressed at 48 hours and 72 hours post-infected whiteflies, respectively. Functional and enrichment analyses indicated that the DNA damage stimulus response and drug metabolism were important anti-fungi strategies of the whitefly. Mitogen-activated protein kinase (MAPK) pathway was also likely involved in the whitefly defense responses. Furthermore, the notable suppression of general metabolism and ion transport genes observed in 72 hours post-infected B. tabaci might be manipulated by fungal secreted effectors. By mapping the sequencing tags to B. bassiana genome, we also identified a number of differentially expressed fungal genes between the early and late infection stages. These genes are generally associated with fungal cell wall synthesis and energy metabolism. The expression of fungal cell wall protein genes might play an important role in fungal pathogenesis and the dramatically up-regulated enzymes of carbon metabolism indicate the increasing usage of energy during the fungal infection. Conclusions/Significance To our knowledge, this is the first report on the molecular mechanism of fungus-whitefly interactions. Our results provide a road map for future investigations on insect-pathogen interactions and genetically modifying the fungus to enhance its efficiency in whitefly control. PMID:23861870

Polysaccharide Production Benefits Dry Storage Survival of the Biocontrol Agent Pseudomonas fluorescens S11:P:12 Effective Against Several Maladies of Stored Potatoes

USDA-ARS?s Scientific Manuscript database

Pseudomonas fluorescens S11:P:12 (NRRL B-21133) is a biological control agent able to suppress several potato diseases and sprouting. Notably, it produces a polysaccharide during liquid cultivation; and the objective of this work was to determine the role of this material in the bio-control process...

Miconia biocontrol: Where are we going and when will we get there?

Treesearch

M.T. Johnson

2010-01-01

We have made much progress in evaluating potential agents for biocontrol of miconia, and several appear likely to be suitable for future introduction to Hawaiÿi. Unfortunately, none of them is an obvious silver bullet. We face the challenge of prioritizing the existing candidates and inventing the combination of agents that will achieve our goals. Now is an opportune...

The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

PubMed

Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

2015-04-01

Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties.

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew.

PubMed

Khalaf, Eman M; Raizada, Manish N

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens ( Rhizoctonia solani , Fusarium graminearum , Phytophthora capsici , Pythium aphanideratum ). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea , the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus . All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro , respectively. These results show that seeds of cultivated cucurbits package microbes with significant disease-suppression potential. As seeds can act as vectors for genetic transmission of endophytes across host generations, it is interesting to hypothesize whether humans, when selecting seeds of healthy hosts, may have inadvertently selected for disease-suppressing seed endophytes. As the majority of pathogen-suppressing endophytes belong to Bacillus and Paenibacillus , and since Bacilli are widely used as commercial biocontrol agents of vegetables, we propose that these agents are mimicking the ecological niche established by their endophytic cousins.

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew

PubMed Central

Khalaf, Eman M.; Raizada, Manish N.

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanidermatum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits package microbes with significant disease-suppression potential. As seeds can act as vectors for genetic transmission of endophytes across host generations, it is interesting to hypothesize whether humans, when selecting seeds of healthy hosts, may have inadvertently selected for disease-suppressing seed endophytes. As the majority of pathogen-suppressing endophytes belong to Bacillus and Paenibacillus, and since Bacilli are widely used as commercial biocontrol agents of vegetables, we propose that these agents are mimicking the ecological niche established by their endophytic cousins. PMID:29459850

Can Plant Microbiome Studies Lead to Effective Biocontrol of Plant Diseases?

PubMed

Ellis, Jeffrey G

2017-03-01

In this review, the wisdom and efficacy of studies seeking disease attenuating microbes and microbiomes only in healthy plant communities is questioned and an alternative view is posited, namely that success in biocontrol of crop diseases may also come from studies of microbiota, or at least individual species isolates, associated with diseased plants. In support of this view, I summarize the current extensive knowledge of the biology behind what is probably the most successful biocontrol of a plant disease, namely the biocontrol of crown gall of stone fruit using non-pathogenic Rhizobium rhizogenes K84, in which the biocontrol agent itself came from a diseased plant.

Responses of Yeast Biocontrol Agents to Environmental Stress

PubMed Central

Sui, Yuan; Wisniewski, Michael; Droby, Samir

2015-01-01

Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeast species, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management of postharvest decay of fruits, vegetables, and grains. A yeast-based biocontrol system is composed of a tritrophic interaction between a host (commodity), a pathogen, and a yeast species, all of which are affected by environmental factors such as temperature, pH, and UV light as well as osmotic and oxidative stresses. Additionally, during the production process, biocontrol agents encounter various severe abiotic stresses that also impact their viability. Therefore, understanding the ecological fitness of the potential yeast biocontrol agents and developing strategies to enhance their stress tolerance are essential to their efficacy and commercial application. The current review provides an overview of the responses of antagonistic yeast species to various environmental stresses, the methods that can be used to improve stress tolerance and efficacy, and the related mechanisms associated with improved stress tolerance. PMID:25710368

Potential of Burkholderia seminalis TC3.4.2R3 as Biocontrol Agent Against Fusarium oxysporum Evaluated by Mass Spectrometry Imaging

NASA Astrophysics Data System (ADS)

Araújo, Francisca Diana da Silva; Araújo, Welington Luiz; Eberlin, Marcos Nogueira

2017-05-01

Species of genus Burkholderia display different interaction profiles in the environment, causing either several diseases in plants and animals or being beneficial to some plants, promoting their growth, and suppressing phytopathogens. Burkholderia spp. also produce many types of biomolecules with antimicrobial activity, which may be commercially used to protect crops of economic interest, mainly against fungal diseases. Herein we have applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate secondary metabolites produced by B. seminalis TC3.4.2R3 in monoculture and coculture with plant pathogen Fusarium oxysporum. The siderophore pyochelin and the rhamnolipid Rha-Rha-C15-C14 were detected in wild-type B. seminalis strain, and their productions were found to vary in mutant strains carrying disruptions in gene clusters associated with antimicrobial compounds. Two mycotoxins were detected in F. oxysporum. During coculture with B. seminalis, metabolites probably related to defense mechanisms of these microorganisms were observed in the interspecies interaction zone. Our findings demonstrate the effective application of MALDI-MSI in the detection of bioactive molecules involved in the defense mechanism of B. seminalis, and these findings suggest the potential use of this bacterium in the biocontrol of plant diseases caused by F. oxysporum.

[Antagonistic interactions between saprotrophic fungi and geohelminths. 2. Saprotrophic fungi in biocontrol of parasitic geohelminths of humans and animals].

PubMed

Jaborowska-Jarmoluk, Magdalena; Mazurkiewicz-Zapałowicz, Kinga; Kołodziejczyk, Lidia

2009-01-01

The soils ecosystem plays an important role in the epidemiology of geohelminth diseases of humans and animals. Soil contamination with ova of the parasitic geohelminths represents a global public health-hazard issue. Biological agents have been thought to control the infective forms of parasites present in the soil. Biocontrol of geohelminths represents an alternative to pesticides (i.e., nematicides), which are not efficient in killing infective nematode forms and, additionally, result in the environment pollution and long-term disturbances in the soil ecosystem homeostasis. The degree of the inhibiting effect of soil saprotrophic fungi on geohelminth embryonic development varies and depends on the species. A number of fungi cause various morphological disorders in the embryos of developing parasitic nematodes, but also have an ovicidal effect. Although the nature of the antagonism between fungi and other living organisms has not been fully explained, it is certain that mycotoxins and fungal enzymes constitute its important components. Considering the studies carried out so far, the antagonistic effect of mold fungi against the infective stages of geohelminths can be fully recommended as a real control factor, especially as these saprotrophs represent a natural factor within the soil environment, that is of particular biochemical activity.

An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes.

PubMed

Kandel, Shyam L; Firrincieli, Andrea; Joubert, Pierre M; Okubara, Patricia A; Leston, Natalie D; McGeorge, Kendra M; Mugnozza, Giuseppe S; Harfouche, Antoine; Kim, Soo-Hyung; Doty, Sharon L

2017-01-01

Microbial communities in the endosphere of Salicaceae plants, poplar ( Populus trichocarpa ) and willow ( Salix sitchensis ), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici , and Pythium ultimum . Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas , and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.

Selective flowers to attract and enhance Telenomus laeviceps (Hymenoptera: Scelionidae): a released biocontrol agent of Mamestra brassicae (Lepidoptera: Noctuidae).

PubMed

Barloggio, G; Tamm, L; Nagel, P; Luka, H

2018-05-10

The importance of the right food source for the survival and reproduction of certain insect species is well documented. In the case of biocontrol agents, this is even more important in order to reach a high predation or parasitation performance. The egg parasitoid Telenomus laeviceps (Förster, 1861) (Hymenoptera: Scelionidae) is a promising candidate for mass release as a biological control agent of the cabbage moth Mamestra brassicae (Linnaeus, 1758) (Lepidoptera: Noctuidae). However, adult T. laeviceps need a sugar-rich food source to increase their parasitation performance and produce a good amount of female offspring. Released biocontrol agents were shown to benefit from conservation biocontrol, which includes the provision of selected flowers as nectar resources for beneficial insects. In Switzerland, Centaurea cyanus L. (Asteraceae), Fagopyrum esculentum Moench (Polygonaceae) and Vicia sativa L. (Fabaceae) are successfully implemented in the field to attract and promote natural enemies of different cabbage pests. In this study, we investigated the potential of these selected flowers to attract and promote T. laeviceps under laboratory conditions. In Y-tube olfactometer experiments, we first tested whether the three nectar providing plant species are attractive to T. laeviceps. Furthermore, we assessed their effects on survival and parasitation performance of adult T. laeviceps. We found that flowers of F. esculentum and C. cyanus were attractive in contrast to V. sativa. Also fecundity and the number of female offspring produced were higher for females kept on F. esculentum and C. cyanus than on V. sativa. In contrast, survival was similar on all treatments. Our findings present a further key step towards the implementation of T. laeviceps as a biocontrol agent.

Genomic characterization of key bacteriophages to formulate the potential biocontrol agent to combat enteric pathogenic bacteria.

PubMed

Parmar, Krupa M; Dafale, Nishant A; Tikariha, Hitesh; Purohit, Hemant J

2018-05-01

Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.

Peptaibol, secondary-metabolite, and hydrophobin pattern of commercial biocontrol agents formulated with species of the Trichoderma harzianum complex.

PubMed

Degenkolb, Thomas; Fog Nielsen, Kristian; Dieckmann, Ralf; Branco-Rocha, Fabiano; Chaverri, Priscila; Samuels, Gary J; Thrane, Ulf; von Döhren, Hans; Vilcinskas, Andreas; Brückner, Hans

2015-04-01

The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics in plant-protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna(®) , Trichosan(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary metabolites, were detected, the latter being known for their antifungal, siderophore, or plant-growth-promoting activities. Notably, none of the isolates produced low-molecular weight mycotoxins. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Draft Genome Sequence of a Biocontrol Rhizobacterium, Chryseobacterium kwangjuense Strain KJ1R5, Isolated from Pepper (Capsicum annuum)

PubMed Central

Jeong, Jin-Ju; Park, Hongjae; Park, Byeong Hyeok; Mannaa, Mohamed; Sang, Mee Kyung

2016-01-01

Strain KJ1R5 of the rhizobacterium Chryseobacterium kwangjuense is an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, Phytophthora capsici. Here, we present the draft genome sequence of strain KJ1R5, which contains genes related to biocontrol, plant growth promotion, and environmental stress adaptation. PMID:27103726

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

PubMed

Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

2013-01-01

Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities

PubMed Central

Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

2013-01-01

Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems. PMID:23840423

Complete Genome Sequence of Ralstonia solanacearum FJAT-1458, a Potential Biocontrol Agent for Tomato Wilt.

PubMed

Chen, Deju; Liu, Bo; Zhu, Yujing; Wang, Jieping; Chen, Zheng; Che, Jiamei; Zheng, Xuefang; Chen, Xiaoqiang

2017-04-06

An avirulent strain of Ralstonia solanacearum FJAT-1458 was isolated from a living tomato. Here, we report the complete R. solanacearum FJAT-1458 genome sequence of 6,059,899 bp and 5,241 genes. This bacterial strain is a potential candidate as a biocontrol agent in the form of a plant vaccine for bacterial wilt. Copyright © 2017 Chen et al.

Purification and Characterization of a New Antifungal Compound 10-(2,2-dimethyl-cyclohexyl)-6,9-dihydroxy-4,9-dimethyl-dec-2-enoic Acid Methyl Ester from Streptomyces hydrogenans Strain DH16

PubMed Central

Kaur, Talwinder; Kaur, Amarjeet; Sharma, Vishal; Manhas, Rajesh K.

2016-01-01

In agriculture, biocontrol agents have been emerged as safe alternative to chemical pesticides where Streptomyces spp. and their metabolites constitute a great potential for their exploration as potent agents for controlling various fungal phytopathogens. The present study reports an antifungal compound purified from Streptomyces hydrogenans strain DH16, a soil isolate, using silica gel chromatography and semi preparative HPLC. The compound was characterized using various spectroscopic techniques (IR, 1H and 13C NMR) and named 10-(2,2-dimethyl-cyclohexyl)-6,9-dihydroxy-4,9-dimethyl-dec-2-enoic acid methyl ester (SH2). Compound (SH2) showed significant inhibitory activity against fungal phytopathogens and resulted in severe morphological aberrations in their structure. Minimal inhibitory and minimal fungicidal concentrations of the compound ranged from 6.25 to 25 μg/ml and 25 to 50 μg/ml, respectively. In vivo evaluation of the compound showed strong control efficacy against Alternaria brassicicola, a seed borne pathogen, on radish seeds. In comparison to mancozeb and carbendazim, the compound was more effective in controlling damping off disease. Additionally, it promoted plant growth with increased rate of seed germination, and displayed no phytotoxicity. The compound retained its antifungal activity after its exposure to temperature of 100°C and sunlight for 1 h. Furthermore, the compound (SH2) when tested for its biosafety was found to be non-cytotoxic, and non-mutagenic against Salmonella typhimurium TA98 and TA100 strains. This compound from S. hydrogenans strain DH16 has not been reported earlier, so this new compound can be developed as an ideal safe and superior biofungicide for the control of various fungal plant diseases. PMID:27446043

Endophytic bacteria from wheat grain as biocontrol agents of Fusarium graminearum and deoxynivalenol production in wheat.

PubMed

Pan, D; Mionetto, A; Tiscornia, S; Bettucci, L

2015-08-01

In Uruguay, Fusarium graminearum is the most common species that infects wheat and is responsible for Fusarium head blight (FHB) and contamination of grain with deoxynivalenol (DON). The aim of this work was to select bacterial endophytes isolated from wheat grain to evaluate their antagonistic ability against F. graminearum and DON production in vitro and under field conditions. Four strains identified as Bacillus megaterium (BM1) and Bacillus subtilis (BS43, BSM0 y BSM2) significantly reduced fungal growth and spore germination of F. graminearum. This antagonist activity remained unchanged after the bacterial cultures were heat treated. Under field conditions, treatments with antagonist BM1 was the most effective, reducing the FHB incidence and severity by 93 and 54 %, respectively, and the production of DON by 89.3 %.

Improving UV resistance and virulence of Beauveria bassiana by genetic engineering with an exogenous tyrosinase gene.

PubMed

Shang, Yanfang; Duan, Zhibing; Huang, Wei; Gao, Qiang; Wang, Chengshu

2012-01-01

Insect pathogenic fungi like Beauveria bassiana have been developed as environmentally friendly biocontrol agents against arthropod pests. However, restrictive environmental factors, including solar ultraviolet (UV) radiation frequently lead to inconsistent field performance. To improve resistance to UV damage, we used Agrobacterium-mediated transformation to engineer B. bassiana with an exogenous tyrosinase gene. The results showed that the mitotically stable transformants produced larger amounts of yellowish pigments than the wild-type strain, and these imparted significantly increased UV-resistance. The virulence of the transgenic isolate was also significantly increased against the silkworm Bombyx mori and the mealworm Tenebrio molitor. This study demonstrated that genetic engineering of B. bassiana with a tyrosinase gene is an effective way to improve fungal tolerance against UV damage. Copyright © 2011 Elsevier Inc. All rights reserved.

Development of an oligonucleotide probe for Aureobasidium pullulans based on the small-subunit rRNA gene.

PubMed Central

Li, S; Cullen, D; Hjort, M; Spear, R; Andrews, J H

1996-01-01

Aureobasidium pullulans, a cosmopolitan yeast-like fungus, colonizes leaf surfaces and has potential as a biocontrol agent of pathogens. To assess the feasibility of rRNA as a target for A. pullulans-specific oligonucleotide probes, we compared the nucleotide sequences of the small-subunit rRNA (18S) genes of 12 geographically diverse A. pullulans strains. Extreme sequence conservation was observed. The consensus A. pullulans sequence was compared with other fungal sequences to identify potential probes. A 21-mer probe which hybridized to the 12 A. pullulans strains but not to 98 other fungi, including 82 isolates from the phylloplane, was identified. A 17-mer highly specific for Cladosporium herbarum was also identified. These probes have potential in monitoring and quantifying fungi in leaf surface and other microbial communities. PMID:8633850

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields-An ecofriendly approach.

PubMed

Ghosh, Swapan Kumar; Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013-2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%-98.57%) but decreased during the winter, December-January (35.71-46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013-15), Trichoderma application restricted the disease to the smallest area (PDI 24.00-29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields.

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields—An ecofriendly approach

PubMed Central

Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013–2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%–98.57%) but decreased during the winter, December-January (35.71–46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013–15), Trichoderma application restricted the disease to the smallest area (PDI 24.00–29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields. PMID:29579070

Rhizoctonia solani infection reduced by bacterial and fungal combination of biofertilizer inoculums on organic potato

NASA Astrophysics Data System (ADS)

Papp, Orsolya; Biro, Borbala; Abod, Eva; Jung, Timea; Tirczka, Imre; Drexler, Dora

2017-04-01

Soil biological functioning and proper agrotechnical management are of key importance in organic agriculture. Beneficial microbial inoculums are used either as plant strengthening products (psp) or also as plant protecting products (ppp). Question is, which type of microbes should be applied to certain soil-plant systems to improve yield or reduce the damage of soil-born plant pathogens? Objective of present study was to compare the effect of inoculums 1 (PPS) with plant growth promoting bacterium strains (PGPR) and inoculums 2 (TPB) with potential biocontrol-agents, including both fungi and bacteria in organic potato production. Field experiment was conducted at the Organic Research Station of the Szent István University (Babatpuszta, Hungary). Growth and quality of potato (Solanum tuberosum var. Demon) was studied in the two microbial treatments and control, in four replicates. The PPS inoculums included Pseudomonas protegens, Ps. jessenii and Strenotrophomonas maltophylia, with plant growth promoting (PGPR) effect. TPB inoculums consisted of Trichoderma hartianum, Pseudomonas putida and Bacillus subtilis strains with main biocontrol effects of fungal and bacterium combination. Strains were incubated for 24 hours at 28 oC in a rotary shaker (140 rpm/min) up till cell-number about 1010 cell.ml-1 in Nutrient broth substrate, and mixed to prepare combined inoculums. Each potato tuber was treated by 10 ml inoculums that was added to 100 ml water respectively with only water at the controls. Yield of potato (10 plants/plot) and tuber quality, i.e. the percentage ratio of scabbiness (Streptomyces scabies), Rhizoctonia solani, and Fusarium sp. infection was estimated. Abundance of total aerob and anaerob heterotrophs, total microscopic fungi, pseudomonads bacteria and some sporeforming microorganisms was assessed by the most probable number (MPN) method in soil samples, collected four times during vegetation. Soil enzyme, dehydrogenase (DH) and fluorescein diacetate (FDA) activity was estimated, beside soil physical and chemical characteristics. Statistics, including binomial logistic regression was used for evaluation (IBM SPSS Statistics 22 software). Aerobic MPN counts were reduced by 0,5 value, anaerobic however were increased by 2 order of magnitude at the end of vegetation period. Both inoculums reduced the fungal counts at 60% of flowering stage, but PPS inoculums improved also the abundance of pseudomonads bacteria in the soil at all sampling stages. Soil dehydrogenase (DH) activity showed a strong seasonal variability, which was about 20-times higher at flowering of potato, more particularly at TPB inoculums. Although yield parameters were only tendentiously improved, the presence of Rhizoctonia solani infected tubers was significantly less likely (by 70,3%) with TPB inoculums combination. We assumed that presence of biocontrol type of Trichoderma fungi in TPB inoculums was the reason for such a significant reduction of Rhizoctonia infection. Necessity of previous monitoring of soil-health, including the microbial status of potential biocontrol strains is concluded. The tuber quality of organic potato may be enhanced by using the inoculums tested in this study. Thematically belongs to Biochar (Piac-13-1-2013-0274) and Biofector (GA 312117) projects.

Buying Time: Preliminary Assessment of Biocontrol in the Recovery of Native Forest Vegetation in the Aftermath of the Invasive Emerald Ash Borer

Treesearch

Elan Margulies; Leah Bauer; Inés Ibáñez

2017-01-01

Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest, the impact on the affected organism, and the indirect impacts that the...

Development of biocontrol agents from food microbial isolates for controlling post-harvest peach brown rot caused by Monilinia fructicola.

PubMed

Zhou, Ting; Schneider, Karin E; Li, Xiu-Zhen

2008-08-15

An unconventional strategy of screening food microbes for biocontrol activity was used to develop biocontrol agents for controlling post-harvest peach brown rot caused by Monilinia fructicola. Forty-four microbial isolates were first screened for their biocontrol activity on apple fruit. Compared with the pathogen-only check, seven of the 44 isolates reduced brown rot incidence by >50%, including four bacteria: Bacillus sp. C06, Lactobacillus sp. C03-b and Bacillus sp. T03-c, Lactobacillus sp. P02 and three yeasts: Saccharomyces delbrueckii A50, S. cerevisiae YE-5 and S. cerevisiae A41. Eight microbial isolates were selected for testing on peaches by wound co-inoculation with mixtures of individual microbial cultures and conidial suspension of M. fructicola. Only two of them showed significant biocontrol activity after five days of incubation at 22 degrees C. Bacillus sp. C06 suppressed brown rot incidence by 92% and reduced lesion diameter by 88% compared to the pathogen-only check. Bacillus sp.T03-c reduced incidence and lesion diameter by 40% and 62%, respectively. The two isolates were compared with Pseudomonas syringae MA-4, a biocontrol agent for post-harvest peach diseases, by immersing peaches in an aliquot containing individual microbial isolates and the pathogen conidia. Treatments with isolates MA-4, C06 and T03-c significantly controlled brown rot by 91, 100, and 100% respectively. However, only isolates MA-4 and C06 significantly reduced brown rot by 80% and 15%, respectively when bacterial cells alone were applied. On naturally infected peaches, both the bacterial culture and its cell-free filtrate of the isolate C06 significantly controlled peach decay resulting in 77 and 90% reduction, respectively, whereas the treatment using only the bacterial cells generally had no effect. Isolate C06 is a single colony isolate obtained from a mesophilic cheese starter, and has been identified belonging to Bacillus amyloliquefaciens. The results have clearly demonstrated that isolate C06 has a great potential for being developed into a biocontrol agent.

Fungal antagonists of the plant pathogen Rhizoctonia solani: selection, control efficacy and influence on the indigenous microbial community.

PubMed

Grosch, Rita; Scherwinski, Katja; Lottmann, Jana; Berg, Gabriele

2006-12-01

A broad spectrum of fungal antagonists was evaluated as potential biocontrol agents (BCAs) against the soil-borne pathogen Rhizoctonia solani using a new combination of in vitro and in vivo assays. The in vitro characterisation of diverse parameters including the ability to parasitise mycelium and to inhibit the germination of Rhizoctonia sclerotia at different temperatures resulted in the selection of six potential fungal antagonists. These were genotypically characterised by their BOX-PCR fingerprints, and identified as Trichoderma reesei and T. viride by partial 18S rDNA sequencing. When potato sprouts were treated with Trichoderma, all isolates significantly reduced the incidence of Rhizoctonia symptoms. Evaluated under growth chamber conditions, the selected Trichoderma isolates either partly or completely controlled the dry mass loss of lettuce caused by R. solani. Furthermore, the antagonistic Trichoderma strains were active under field conditions. To analyse the effect of Trichoderma treatment on indigenous root-associated microbial communities, we performed a DNA-dependent SSCP (Single-Strand Conformation Polymorphism) analysis of 16S rDNA/ITS sequences. In this first assessment study for Trichoderma it was shown that the pathogen and the vegetation time had much more influence on the composition of the microbiota than the BCA treatment. After evaluation of all results, three Trichoderma strains originally isolated from Rhizoctonia sclerotia were selected as promising BCAs.

The Ste12-like transcription factor MaSte12 is involved in pathogenicity by regulating the appressorium formation in the entomopathogenic fungus, Metarhizium acridum.

PubMed

Wei, Qinglv; Du, Yanru; Jin, Kai; Xia, Yuxian

2017-12-01

Homeodomain transcription factor Ste12 is a key target activated by the pathogenic mitogen-activated-protein kinase pathway, and the activated Ste12p protein regulates downstream gene expression levels to modulate phenotypes. However, the functions of Ste12-like genes in entomopathogenic fungi remain poorly understood and little is known about the downstream genes regulated by Ste12. In this study, we characterized the functions of a Ste12 orthologue in Metarhizium acridum, MaSte12, and identified its downstream target genes. The deletion mutant (ΔMaSte12) is defective in conidial germination but not in hyphal growth, conidiation, or stress tolerance. Bioassays showed that ΔMaSte12 had a dramatically decreased virulence in topical inoculations, but no significant difference was found in intrahemolymph injections when the penetration process was bypassed. The mature appressorium formation rate of ΔMaSte12 was less than 10% on locust wings, with the majority hyphae forming appressorium-like, curved but no swollen structures. Digital gene expression profiling revealed that some genes involved in cell wall synthesis and remodeling, appressorium development, and insect cuticle penetration were downregulated in ΔMaSte12. Thus, MaSte12 has critical roles in the pathogenicity of the entomopathogenic fungus M. acridum, and our study provides some explanations for the impairment of fungal virulence in ΔMaSte12. In addition, virulence is very important for fungal biocontrol agents to control insect pests effectively. This study demonstrated that MaSte12 is involved in fungal virulence but not conidial yield or fungal stress tolerance in M. acridum. Thus, MaSte12 and its downstream genes may be candidates for enhancing fungal virulence to improve mycoinsecticides.

Bio-prospecting of distillery yeasts as bio-control and bio-remediation agents.

PubMed

Ubeda, Juan F; Maldonado, María; Briones, Ana I; Francisco, J Fernández; González, Francisco J

2014-05-01

This work constitutes a preliminary study in which the capacity of non-Saccharomyces yeasts isolated from ancient distilleries as bio-control agents against moulds and in the treatment of waste waters contaminated by heavy metals-i.e. bio-remediation-is shown. In the first control assays, antagonist effect between non-Saccharomyces yeasts, their extracts and supernatants against some moulds, analysing the plausible (not exhaustive) involved factors were qualitatively verified. In addition, two enzymatic degrading properties of cell wall plant polymers, quitinolitic and pectinolitic, were screened. Finally, their use as agents of bio-remediation of three heavy metals (cadmium, chromium and lead) was analysed semi-quantitatively. The results showed that all isolates belonging to Pichia species effectively inhibited all moulds assayed. Moreover, P. kudriavzevii is a good candidate for both bio-control and bio-remediation because it inhibited moulds and accumulated the major proportion of the three tested metals.

Effect of bacterial antagonists on lettuce: active biocontrol of Rhizoctonia solani and negligible, short-term effects on nontarget microorganisms.

PubMed

Scherwinski, Katja; Grosch, Rita; Berg, Gabriele

2008-04-01

The aim of this study was to assess the biocontrol efficacy against Rhizoctonia solani of three bacterial antagonists introduced into naturally Rhizoctonia-infested lettuce fields and to analyse their impact on the indigenous plant-associated bacteria and fungi. Lettuce seedlings were inoculated with bacterial suspensions of two endophytic strains, Serratia plymuthica 3Re4-18 and Pseudomonas trivialis 3Re2-7, and with the rhizobacterium Pseudomonas fluorescens L13-6-12 7 days before and 5 days after planting in the field. Similar statistically significant biocontrol effects were observed for all applied bacterial antagonists compared with the uninoculated control. Single-strand conformation polymorphism analysis of 16S rRNA gene or ITS1 fragments revealed a highly diverse rhizosphere and a less diverse endophytic microbial community for lettuce. Representatives of several bacterial (Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Bacteriodetes), fungal (Ascomycetes, Basidiomycetes) and protist (Oomycetes) groups were present inside or on lettuce plants. Surprisingly, given that lettuce is a vegetable that is eaten raw, species of genera such as Flavobacterium, Burkholderia, Staphylococcus, Cladosporium and Aspergillus, which contain potentially human pathogenic strains, were identified. Analysis of the indigenous bacterial and endophytic fungal populations revealed only negligible, short-term effects resulting from the bacterial treatments, and that they were more influenced by field site, plant growth stage and microenvironment.

Evidence for Biotrophic Lifestyle and Biocontrol Potential of Dark Septate Endophyte Harpophora oryzae to Rice Blast Disease

PubMed Central

Su, Zhen-Zhu; Mao, Li-Juan; Li, Na; Feng, Xiao-Xiao; Yuan, Zhi-Lin; Wang, Li-Wei; Lin, Fu-Cheng; Zhang, Chu-Long

2013-01-01

The mutualism pattern of the dark septate endophyte (DSE) Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA) signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS) and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast. PMID:23637814

A method of multiplex PCR for detection of field released Beauveria bassiana, a fungal entomopathogen applied for pest management in jute (Corchorus olitorius).

PubMed

Biswas, Chinmay; Dey, Piyali; Gotyal, B S; Satpathy, Subrata

2015-04-01

The fungal entomopathogen Beauveria bassiana is a promising biocontrol agent for many pests. Some B. bassiana strains have been found effective against jute pests. To monitor the survival of field released B. bassiana a rapid and efficient detection technique is essential. Conventional methods such as plating method or direct culture method which are based on cultivation on selective media followed by microscopy are time consuming and not so sensitive. PCR based methods are rapid, sensitive and reliable. A single primer PCR may fail to amplify some of the strains. However, multiplex PCR increases the possibility of detection as it uses multiple primers. Therefore, in the present investigation a multiplex PCR protocol was developed by multiplexing three primers SCA 14, SCA 15 and SCB 9 to detect field released B. bassiana strains from soil as well as foliage of jute field. Using our multiplex PCR protocol all the five B. bassiana strains could be detected from soil and three strains viz., ITCC 6063, ITCC 4563 and ITCC 4796 could be detected even from the crop foliage after 45 days of spray.

Species-Specific Detection of Mycosphaerella polygoni-cuspidati as a Biological Control Agent for Fallopia japonica by PCR Assay.

PubMed

Kurose, Daisuke; Furuya, Naruto; Saeki, Tetsuya; Tsuchiya, Kenichi; Tsushima, Seiya; Seier, Marion K

2016-10-01

The ascomycete fungus Mycosphaerella polygoni-cuspidati has been undergoing evaluation as a potential classical biological control agent for the invasive weed Fallopia japonica (Japanese knotweed), which has become troublesome in Europe and North America. In advance of the potential release of a biocontrol agent into a new environment, it is crucial to develop an effective monitoring system to enable the evaluation of agent establishment and dispersal within the target host population, as well as any potential attacks on non-target species. Therefore, a primer pair was designed for direct, rapid, and specific detection of the Japanese knotweed pathogen M. polygoni-cuspidati based on the sequences of the internal transcribed spacer regions including the 5.8S rDNA. A PCR product of approximately 298 bp was obtained only when the DNA extracted from mycelial fragments of M. polygoni-cuspidati was used. The lower limit of detection of the PCR method was 100 fg of genomic DNA. Using the specific primer pair, M. polygoni-cuspidati could be detected from both naturally and artificially infected Japanese knotweed plants. No amplification was observed for other Mycosphaerella spp. or fungal endophytes isolated from F. japonica. The designed primer pair is thus effective for the specific detection of M. polygoni-cuspidati in planta.

Enzymatic comparison and mortality of Beauveria bassiana against cabbage caterpillar Pieris brassicae LINN.

PubMed

Dhawan, Manish; Joshi, Neelam

Beauveria bassiana, an entomopathogenic fungus, is the alternative biocontrol agent exploited against major economic crop pests. Pieris brassicae L. is an emerging pest of the Brassicaceae family. Therefore, in the present study, fungal isolates of Beauveria bassiana, viz. MTCC 2028, MTCC 4495, MTCC 6291, and NBAII-11, were evaluated for their virulence against third instar larvae of P. brassicae. Among all these fungal isolates, maximum mortality (86.66%) was recorded in B. bassiana MTCC 4495 at higher concentration of spores (10 9 conidia/ml), and the minimum mortality (30.00%) was recorded in B. bassiana MTCC 6291 at a lower concentration (10 7 conidia/ml) after ten days of treatment. The extracellular cuticle-degrading enzyme activities of fungal isolates were measured. Variability was observed both in the pattern of enzyme secretion and the level of enzyme activities among various fungal isolates. B. bassiana MTCC 4495 recorded the maximum mean chitinase (0.51U/ml), protease (1.12U/ml), and lipase activities (1.36U/ml). The minimum mean chitinase and protease activities (0.37 and 0.91U/ml, respectively) were recorded in B. bassiana MTCC 6291. The minimum mean lipase activity (1.04U/ml) was recorded in B. bassiana NBAII-11. Our studies revealed B. bassiana MTCC 4495 as the most pathogenic isolate against P. brassicae, which also recorded maximum extracellular enzyme activities, suggesting the possible roles of extracellular enzymes in the pathogenicity of B. bassiana against P. brassicae. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Belowground communication: impacts of volatile organic compounds (VOCs) from soil fungi on other soil-inhabiting organisms.

PubMed

Werner, Stephanie; Polle, Andrea; Brinkmann, Nicole

2016-10-01

We reviewed the impact of fungal volatile organic compounds (VOCs) on soil-inhabiting organisms and their physiological and molecular consequences for their targets. Because fungi can only move by growth to distinct directions, a main mechanism to protect themselves from enemies or to manipulate their surroundings is the secretion of exudates or VOCs. The importance of VOCs in this regard has been significantly underestimated. VOCs not only can be means of communication, but also signals that are able to specifically manipulate the recipient. VOCs can reprogram root architecture of symbiotic partner plants or increase plant growth leading to enlarged colonization surfaces. VOCs are also able to enhance plant resistance against pathogens by activating phytohormone-dependent signaling pathways. In some cases, they were phytotoxic. Because the response was specific to distinct species, fungal VOCs may contribute to regulate the competition of plant communities. Additionally, VOCs are used by the producing fungus to attack rivaling fungi or bacteria, thereby protecting the emitter or its nutrient sources. In addition, animals, like springtails, nematodes, and earthworms, which are important components of the soil food web, respond to fungal VOCs. Some VOCs are effective repellents for nematodes and, therefore, have applications as biocontrol agents. In conclusion, this review shows that fungal VOCs have a huge impact on soil fauna and flora, but the underlying mechanisms, how VOCs are perceived by the recipients, how they manipulate their targets and the resulting ecological consequences of VOCs in inter-kingdom signaling is only partly understood. These knowledge gaps are left to be filled by future studies.

Possibility of biological control of primocane fruiting raspberry disease caused by Fusarium sambucinum.

PubMed

Shternshis, Margarita V; Belyaev, Anatoly A; Matchenko, Nina S; Shpatova, Tatyana V; Lelyak, Anastasya A

2015-10-01

Biological control agents are a promising alternative to chemical pesticides for plant disease suppression. The main advantage of the natural biocontrol agents, such as antagonistic bacteria compared with chemicals, includes environmental pollution prevention and a decrease of chemical residues in fruits. This study is aimed to evaluate the impact of three Bacillus strains on disease of primocane fruiting raspberry canes caused by Fusarium sambucinum under controlled infection load and uncontrolled environmental factors. Bacillus subtilis, Bacillus licheniformis, and Bacillus amyloliquefaciens were used for biocontrol of plant disease in 2013 and 2014 which differed by environmental conditions. The test suspensions were 10(5) CFU/ml for each bacterial strain. To estimate the effect of biological agents on Fusarium disease, canes were cut at the end of vegetation, and the area of outer and internal lesions was measured. In addition to antagonistic effect, the strains revealed the ability to induce plant resistance comparable with chitosan-based formulation. Under variable ways of cane treatment by bacterial strains, the more effective were B. subtilis and B. licheniformis demonstrating dual biocontrol effect. However, environmental factors were shown to impact the strain biocontrol ability; changes in air temperature and humidity led to the enhanced activity of B. amyloliquefaciens. For the first time, the possibility of replacing chemicals with environmentally benign biological agents for ecologically safe control of the raspberry primocane fruiting disease was shown.

Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

NASA Astrophysics Data System (ADS)

Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

2013-10-01

Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

Mating-type heterokaryosis and population shifts in Aspergillus flavus

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus is a fungal pathogen of many agronomically important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, NC. This field was planted in 2010 and plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of...

Population shifts and mating-type heterokaryosis in Aspergillus flavus

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus is a fungal pathogen of many agronomically important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, NC. This field was planted in 2010 and plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of...

Reaction of Diaporthe longicolla to a strain of Sarocladium kiliense

USDA-ARS?s Scientific Manuscript database

Phomopsis seed decay (PSD) of soybean [Glycine max (L.) Merr.] is a seedborne fungal disease caused by Diaporthe (syn. Phomopsis) longicolla that causes yield losses and reduced seed quality. Biocontrol of this pathogen by a strain of Acremonium strictum isolated from a culture of D. longicolla was ...

Potentialities of Mermithid Nematodes for the Biocontrol of Blackflies (Diptera: Simuliidae)--A Review,

DTIC Science & Technology

biocontrol agents of agricultural insect pests and medically important insect vectors. More specifically, mermithid nematodes appear to regulate natural...Mermithids comprise a family of nematodes which invariably kill/sterilize their insect host(s). These nematodes have considerable potential as

Production of prodigiosin and chitinases by tropical Serratia marcescens strains with potential to control plant pathogens.

PubMed

Gutiérrez-Román, Martha Ingrid; Holguín-Meléndez, Francisco; Bello-Mendoza, Ricardo; Guillén-Navarro, Karina; Dunn, Michael F; Huerta-Palacios, Graciela

2012-01-01

The potential of three Serratia marcescens strains (CFFSUR-B2, CFFSUR-B3 and CFFSUR-B4) isolated from tropical regions in Mexico to inhibit the mycelial growth and conidial germination of Colletotrichum gloeosporioides, causal agent of fruit anthracnose, was evaluated. The ability of these strains to produce prodigiosin and chitinases when cultivated in oil seed-based media (peanut, sesame, soybean and castor bean) and in Luria-Bertani medium was determined. All of the strains exhibited similar fungal antagonistic activities and inhibited myceliar growth by more than 40% while inhibiting conidial germination by 81-89% (P = 0.01). The highest level of prodigiosin (40 μg/ml) was produced in the peanut-based medium while growth in soybean-based medium allowed the highest production of chitinases (56 units/ml), independent of the strain used. Strain CFFSUR-B2 grown in peanut medium was used to evaluate the effect of inoculum density and initial pH on metabolite production. The amount of prodigiosin produced increased with greater inoculum densities, with an initial density of 1 × 10(12) resulting in the highest production (60 μg/ml). Prodigiosin production was not affected by pH. The strains studied have the advantage of being adapted to tropical climates and are able to produce chitinases in the absence of chitin induction in vitro. These characteristics suggest their potential as biocontrol agents for fungal pathogens in tropical regions of the world.

Laboratory and field evaluation of an entomopathogenic fungus, Isaria cateniannulata strain 08XS-1, against Tetranychus urticae (Koch).

PubMed

Zhang, Xiaona; Jin, Daochao; Zou, Xiao; Guo, Jianjun

2016-05-01

The two-spotted mite, Tetranychus urticae Koch, is one of the most serious mite pests of crops throughout the world. Biocontrol of the mite with fungal agents has long been paid much attention because of the development of insecticide resistance and the severe restriction of chemical pesticides. In this study, the efficacy of submerged conidia of the entomopathogenic fungus Isaria cateniannulata strain 08XS-1 against T. urticae eggs, larvae and female adults was evaluated at different temperatures and humidity in the laboratory and under field conditions. The results showed that a suspension of 2 × 10(7) submerged conidia mL(-1) caused the highest mortalities of mite eggs, larvae and females (100, 100 and 70% respectively) at 100% relative humidity and 25 °C in the laboratory. In the field experiments against the mites, a suspension of 2 × 10(8) submerged conidia mL(-1) achieved significant efficiency - the relative control effects were 88.6, 83.8 and 83%, respectively, in cucumber, eggplant and bean fields after 10 days of treatment. The results suggest that the I. cateniannulata strain 08XS-1 is a potential fungal agent, with acceptable production cost of conidia, against T. urticae in the field in an area such as southwestern China with higher air humidity. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Spore Acquisition and Survival of Ambrosia Beetles Associated with the Laurel Wilt Pathogen in Avocados after Exposure to Entomopathogenic Fungi.

PubMed

Avery, Pasco B; Bojorque, Verónica; Gámez, Cecilia; Duncan, Rita E; Carrillo, Daniel; Cave, Ronald D

2018-04-25

Laurel wilt is a disease threatening the avocado industry in Florida. The causative agent of the disease is a fungus vectored by ambrosia beetles that bore into the trees. Until recently, management strategies for the vectors of the laurel wilt fungus relied solely on chemical control and sanitation practices. Beneficial entomopathogenic fungi (EPF) are the most common and prevalent natural enemies of pathogen vectors. Laboratory experiments demonstrated that commercial strains of EPF can increase the mortality of the primary vector, Xyleborus glabratus , and potential alternative vectors, Xylosandrus crassiusculus , Xyleborus volvulus and Xyleborus bispinatus (Coleoptera: Curculionidae: Scolytinae). Our study provides baseline data for three formulated commercially-available entomopathogenic fungi used as potential biocontrol agents against X. crassiusculus , X. volvulus and X. bispinatus. The specific objectives were to determine: (1) the mean number of viable spores acquired per beetle species adult after being exposed to formulated fungal products containing different strains of EPF ( Isaria fumosorosea , Metarhizium brunneum and Beauveria bassiana ); and (2) the median and mean survival times using paper disk bioassays. Prior to being used in experiments, all fungal suspensions were adjusted to 2.4 × 10⁶ viable spores/mL. The number of spores acquired by X. crassiusculus was significantly higher after exposure to B. bassiana , compared to the other fungal treatments. For X. volvulus , the numbers of spores acquired per beetle were significantly different amongst the different fungal treatments, and the sequence of spore acquisition rates on X. volvulus from highest to lowest was I. fumosorosea > M. brunneum > B. bassiana . After X. bispinatus beetles were exposed to the different suspensions, the rates of acquisition of spores per beetle amongst the different fungal treatments were similar. Survival estimates (data pooled across two tests) indicated an impact for each entomopathogenic fungus per beetle species after exposure to a filter paper disk treated at the same fungal suspension concentration. Kaplan⁻Meier analysis (censored at day 7) revealed that each beetle species survived significantly shorter in bioassays containing disks treated with EPF compared to water only. This study demonstrated that ambrosia beetles associated with the laurel wilt pathogen in avocados are susceptible to infection by EPF under laboratory conditions. However, the EPF needs to be tested under field conditions to confirm their efficacy against the beetles.

Biological Control of Aflatoxin Contamination in U.S. Crops and the Use of Bioplastic Formulations of Aspergillus flavus Biocontrol Strains To Optimize Application Strategies.

PubMed

Abbas, Hamed K; Accinelli, Cesare; Shier, W Thomas

2017-08-23

Aflatoxin contamination has a major economic impact on crop production in the southern United States. Reduction of aflatoxin contamination in harvested crops has been achieved by applying nonaflatoxigenic biocontrol Aspergillus flavus strains that can out-compete wild aflatoxigenic A. flavus, reducing their numbers at the site of application. Currently, the standard method for applying biocontrol A. flavus strains to soil is using a nutrient-supplying carrier (e.g., pearled barley for Afla-Guard). Granules of Bioplastic (partially acetylated corn starch) have been investigated as an alternative nutritive carrier for biocontrol agents. Bioplastic granules have also been used to prepare a sprayable biocontrol formulation that gives effective reduction of aflatoxin contamination in harvested corn kernels with application of much smaller amounts to leaves later in the growing season. The ultimate goal of biocontrol research is to produce biocontrol systems that can be applied to crops only when long-range weather forecasting indicates they will be needed.

Enhancement of a Novel Isolate of Serratia plymuthica as Potential Candidate for an Antianthracnose.

PubMed

Aisyah, Siti Nur; Harnas, Hafid; Sulastri, Sulastri; Retmi, Retmi; Fuaddi, Helmi; Fatchiyah, Fatchiyah; Bakhtiar, Amri; Jamsari, Jamsari

A new rhizobacteria isolate of Serratia plymuthica (strain UBCR_12) exhibited a promising potential as a biocontrol agent for anthracnose causing agent Colletotrichum gloeosporioides. The aim of this study was to characterize its antagonistic activity and explore the factors contributing to a higher inhibition activity. The antifungal effect of UBCR_12 against C. gloeosporioides was assayed under various pH values and nutritional sources. Culture supernatant obtained from UBCR_12 and C. gloeosporioides co-culture was also tested for its inhibitory activity. In addition, the antagonistic range of this isolate was examined against Sclerotium rolfsii and Fusarium oxysporum. Statistical analysis was done using one way analysis of variance and further processed using Fisher's Least Significant Difference (LSD) test with a p<0.05. The UBCR_12 induced inhibition was shown to be stable over time at pH 7, while peptone addition led to a faster induction (2 days after treatment) and glucose treatment to a higher activity. Of all these modifications, preliminary co-culture experiments with fungal cells resulted in the best antagonistic activity of UBCR_12 culture supernatant of about 30.66%. This isolate also showed a wide range of antagonistic activity due to its high suppression against S. rolfsii and F. oxysporum from soybean. Both environmental and biotic manipulations contributed an elevated inhibition rate of UBCR_12 against C. gloeosporioides. A proportional combination of the factors stimulating antagonistic activity of this strain is recommended to be utilized for the development of this strain as an antianthracnose. The enhanced antifungal effects of UBCR_12 resulted under each type of modification were varied indicating the difference of cell responses. It suggests that certain antifungal mechanism could be generated by modifying the environmental factor required for its induction. In addition, the application of cell-free culture supernatant provides an alternative solution in the utilization of biocontrol agents. For large scale application, it could minimize the risk of population outbreaks and harmful effects due to the living cells application.

From effective biocontrol agent to successful invader: the harlequin ladybird (Harmonia axyridis) as an example of good ideas that could go wrong

PubMed Central

Ortega-Iturriaga, Adrián; del-Val, Ek

2017-01-01

The use of biological control agents to control pests is an alternative to pesticides and a tool to manage invasive alien species. However, biocontrol agents can themselves become invasive species under certain conditions. The harlequin ladybird (Harmonia axyridis) is a native Asian biocontrol agent that has become a successful invader. We reviewed articles containing “Harmonia axyridis” to gather information on its presence and surveyed entomologists researching Coccinellidae around the world to investigate further insights about the current distribution, vectors of introduction, habitat use and threats this species pose. The harlequin ladybird has established populations in at least 59 countries outside its native range. Twenty six percent of the surveyed scientists considered it a potential threat to native Coccinellidae. Published studies and scientists suggest Adalia bipunctata, native to Europe, is under the highest risk of population declines. Strict policies should be incorporated to prevent its arrival to non-invaded areas and to prevent further expansion range. Managing invasive species is a key priority to prevent biodiversity loss and promote ecosystem services. PMID:28533958

From effective biocontrol agent to successful invader: the harlequin ladybird (Harmonia axyridis) as an example of good ideas that could go wrong.

PubMed

Camacho-Cervantes, Morelia; Ortega-Iturriaga, Adrián; Del-Val, Ek

2017-01-01

The use of biological control agents to control pests is an alternative to pesticides and a tool to manage invasive alien species. However, biocontrol agents can themselves become invasive species under certain conditions. The harlequin ladybird ( Harmonia axyridis ) is a native Asian biocontrol agent that has become a successful invader. We reviewed articles containing " Harmonia axyridis " to gather information on its presence and surveyed entomologists researching Coccinellidae around the world to investigate further insights about the current distribution, vectors of introduction, habitat use and threats this species pose. The harlequin ladybird has established populations in at least 59 countries outside its native range. Twenty six percent of the surveyed scientists considered it a potential threat to native Coccinellidae. Published studies and scientists suggest Adalia bipunctata , native to Europe, is under the highest risk of population declines. Strict policies should be incorporated to prevent its arrival to non-invaded areas and to prevent further expansion range. Managing invasive species is a key priority to prevent biodiversity loss and promote ecosystem services.

Testing the efficacy of eGFP-transformed Aspergillus flavus as biocontrol strains

USDA-ARS?s Scientific Manuscript database

Current biological control methods to prevent pre-harvest aflatoxin contamination of corn, cottonseed, and ground and tree nuts involve field inoculation of non-aflatoxigenic Aspergillus flavus. To date, the efficacy of this approach requires annual reapplication of the biocontrol agent. The reason ...

Of smuts, blasts, mildews, and blights: cAMP signaling in phytopathogenic fungi.

PubMed

Lee, Nancy; D'Souza, Cletus A; Kronstad, James W

2003-01-01

cAMP regulates morphogenesis and virulence in a wide variety of fungi including the plant pathogens. In saprophytic yeasts such as Saccharomyces cerevisiae, cAMP signaling plays an important role in nutrient sensing. In filamentous saprophytes, the cAMP pathway appears to play an integral role in vegetative growth and sporulation, with possible connections to mating. Infection-related morphogenesis includes sporulation (conidia and teliospores), formation of appressoria, infection hyphae, and sclerotia. Here, we review studies of cAMP signaling in a variety of plant fungal pathogens. The primary fungi to be considered include Ustilago maydis, Magnaporthe grisea, Cryphonectria parasitica, Colletotrichum and Fusarium species, and Erisyphe graminis. We also include related information on Trichoderma species that act as mycoparasites and biocontrol agents of phytopathogenic fungi. We point out similarities in infection mechanisms, conservation of signaling components, as well as instances of cross-talk with other signaling pathways.

Investigation on the infection mechanism of the fungus Clonostachys rosea against nematodes using the green fluorescent protein.

PubMed

Zhang, Lin; Yang, Jinkui; Niu, Qiuhong; Zhao, Xuna; Ye, Fengping; Liang, Lianming; Zhang, Ke-Qin

2008-04-01

The fungus Clonostachys rosea (syn. Gliocladium roseum) is a potential biocontrol agent. It can suppress the sporulation of the plant pathogenic fungus Botrytis cinerea and kill pathogenic nematodes, but the process of nematode pathogenesis is poorly understood. To help understand the underlying mechanism, we constructed recombinant strains containing a plasmid with both the enhanced green fluorescent protein gene egfp and the hygromycin resistance gene hph. Expression of the green fluorescent protein (GFP) was monitored using fluorescence microscopy. Our observations reveal that the pathogenesis started from the adherence of conidia to nematode cuticle for germination, followed by the penetration of germ tubes into the nematode body and subsequent death and degradation of the nematodes. These are the first findings on the infection process of the fungal pathogen marked with GFP, and the developed method can become an important tool for studying the molecular mechanisms of nematode infection by C. rosea.

Cloning, annotation and expression analysis of mycoparasitism-related genes in Trichoderma harzianum 88.

PubMed

Yao, Lin; Yang, Qian; Song, Jinzhu; Tan, Chong; Guo, Changhong; Wang, Li; Qu, Lianhai; Wang, Yun

2013-04-01

Trichoderma harzianum 88, a filamentous soil fungus, is an effective biocontrol agent against several plant pathogens. High-throughput sequencing was used here to study the mycoparasitism mechanisms of T. harzianum 88. Plate confrontation tests of T. harzianum 88 against plant pathogens were conducted, and a cDNA library was constructed from T. harzianum 88 mycelia in the presence of plant pathogen cell walls. Randomly selected transcripts from the cDNA library were compared with eukaryotic plant and fungal genomes. Of the 1,386 transcripts sequenced, the most abundant Gene Ontology (GO) classification group was "physiological process". Differential expression of 19 genes was confirmed by real-time RT-PCR at different mycoparasitism stages against plant pathogens. Gene expression analysis revealed the transcription of various genes involved in mycoparasitism of T. harzianum 88. Our study provides helpful insights into the mechanisms of T. harzianum 88-plant pathogen interactions.

Weed biocontrol in the EU: from serendipity to strategy

USDA-ARS?s Scientific Manuscript database

Biological control of weeds is a globally-recognized approach to the management of the worst invasive plants in the world. Unfortunately, accidental introduction of agents account for most weed biocontrol in the EU, but do include a number of current or emerging successes. From the redistribution of...

Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

USDA-ARS?s Scientific Manuscript database

A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

Use of biocontrol organisms and compost amendments for improved control of soilborne diseases and increased potato production

USDA-ARS?s Scientific Manuscript database

Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evalua...

Growth kinetics and efficacy as parameters for ranking and selecting biocontrol agents that reduce pink rot in stored potatoes

USDA-ARS?s Scientific Manuscript database

Increased production of organic agricultural products and the relative ineffectiveness of traditional control measures support development of new biocontrol technologies for use against pink rot infections in storage. The microbiota of 84 different agricultural soils was individually transferred to...

Recent Trends in Salmonella Outbreaks and Emerging Technology for Biocontrol of Salmonella Using Phages in Foods: A Review.

PubMed

Oh, Jun-Hyun; Park, Mi-Kyung

2017-12-28

Salmonella is one of the principal causes of foodborne outbreaks. As traditional control methods have shown less efficacy against emerging Salmonella serotypes or antimicrobialresistant Salmonella , new approaches have been attempted. The use of lytic phages for the biocontrol of Salmonella in the food industry has become an attractive method owing to the many advantages offered by the use of phages as biocontrol agents. Phages are natural alternatives to traditional antimicrobial agents; they have proven effective in the control of bacterial pathogens in the food industry, which has led to the development of different phage products. The treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases, and ultimately promotes safe environments for animal and plant food production, processing, and handling. After an extensive investigation of the current literature, this review focuses predominantly on the efficacy of phages for the successful control of Salmonella spp. in foods. This review also addresses the current knowledge on the pathogenic characteristics of Salmonella , the prevalence of emerging Salmonella outbreaks, the isolation and characterization of Salmonella -specific phages, the effectiveness of Salmonella -specific phages as biocontrol agents, and the prospective use of Salmonella -specific phages in the food industry.

Use of mixed cultures of biocontrol agents to control sheep nematodes.

PubMed

Baloyi, M A; Laing, M D; Yobo, K S

2012-03-23

Biological control is a promising non-chemical approach for the control of gastrointestinal nematodes of sheep. Use of combinations of biocontrol agents have been reported to be an effective method to increase the efficacy of biological control effects. In this study, combinations of either two Bacillus thuringiensis (Bt) or Clonostachys rosea (C. rosea) isolates and Bt+C. rosea isolates were evaluated in vitro in microtitre plates for their biocontrol activity on sheep nematodes. The Baermann technique was used to extract the surviving L3 larval stages of intestinal nematodes and counted under a dissecting microscope to determine the larval counts. Results indicate that there was a significant reduction of nematode counts due to combination of biocontrol agents (P<0.001). Combinations of Bt isolates reduced nematodes counts by 72.8%, 64% and 29.8%. The results revealed a control level of 57% when C. rosea isolates P3+P8 were combined. Combination of Bt and C. rosea isolates B10+P8 caused the greatest mortality of 76.7%. Most combinations were antagonistic, with only a few combinations showing an additive effect. None were synergistic. The isolate combinations were more effective than when isolates were used alone. Copyright © 2011 Elsevier B.V. All rights reserved.

Efficacy of fungal and bacterial antagonists for controlling growth, FUM1 gene expression and fumonisin B1 production by Fusarium verticillioides on maize cobs of different ripening stages.

PubMed

Samsudin, Nik Iskandar Putra; Rodriguez, Alicia; Medina, Angel; Magan, Naresh

2017-04-04

This study was carried out to examine the efficacy of two biocontrol agents (Clonostachys rosea 016, BCA1; Gram-negative bacterium, BCA5) for control of FUM1 gene expression and fumonisin B 1 (FB 1 ) production by F. verticillioides FV1 on maize cobs of different ripening stages: R 3 , Milk (0.985 a w ); R 4 , Dough (0.976 a w ); R 5 , Dent (0.958 a w ). Initially, temporal studies on FUM1 gene expression and FB 1 production were performed on maize kernels for up to 14days. This revealed that day 10 was optimum for both parameters, and was used in the biocontrol studies. Maize cobs were inoculated with 50:50 mixtures of the pathogen:antagonist inoculum and incubated in environmental chambers to maintain the natural a w conditions for ten days at 25 and 30°C. The growth rates of F. verticillioides FV1, the relative expression of the FUM1 gene and FB 1 production were quantified. It was found that, a w ×temp had significant impacts on growth, FUM1 gene expression and FB 1 production by F. verticillioides FV1 on maize cobs of different maturities. The fungal antagonist (BCA1) significantly reduced FB 1 contamination on maize cobs by >70% at 25°C, and almost 60% at 30°C regardless of maize ripening stage. For the bacterial antagonist (BCA5) however, FB 1 levels on maize cobs were significantly decreased only in some treatments. These results suggest that efficacy of antagonists to control mycotoxin production in ripening maize cobs needs to take account of the ecophysiology of the pathogen and the antagonists, as well as the physiological status of the maize during silking to ensure effective control. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative analysis of the repertoire of G protein-coupled receptors of three species of the fungal genus Trichoderma

PubMed Central

2013-01-01

Background Eukaryotic organisms employ cell surface receptors such as the seven-transmembrane G protein-coupled receptors (GPCRs) as sensors to connect to the environment. GPCRs react to a variety of extracellular cues and are considered to play central roles in the signal transduction in fungi. Several species of the filamentous ascomycete Trichoderma are potent mycoparasites, i.e. can attack and parasitize other fungi, which turns them into successful bio-fungicides for the protection of plants against fungal phytopathogens. The identification and characterization of GPCRs will provide insights into how Trichoderma communicates with its environment and senses the presence of host fungi. Results We mined the recently published genomes of the two mycoparasitic biocontrol agents Trichoderma atroviride and Trichoderma virens and compared the identified GPCR-like proteins to those of the saprophyte Trichoderma reesei. Phylogenetic analyses resulted in 14 classes and revealed differences not only among the three Trichoderma species but also between Trichoderma and other fungi. The class comprising proteins of the PAQR family was significantly expanded both in Trichoderma compared to other fungi as well as in the two mycoparasites compared to T. reesei. Expression analysis of the PAQR-encoding genes of the three Trichoderma species revealed that all except one were actually transcribed. Furthermore, the class of receptors with a DUF300 domain was expanded in T. atroviride, and T. virens showed an expansion of PTH11-like receptors compared to T. atroviride and T. reesei. Conclusions Comparative genome analyses of three Trichoderma species revealed a great diversity of putative GPCRs with genus- and species- specific differences. The expansion of certain classes in the mycoparasites T. atroviride and T. virens is likely to reflect the capability of these fungi to establish various ecological niches and interactions with other organisms such as fungi and plants. These GPCRs consequently represent interesting candidates for future research on the mechanisms underlying mycoparasitism and biocontrol. PMID:23679152

Comparative analysis of the repertoire of G protein-coupled receptors of three species of the fungal genus Trichoderma.

PubMed

Gruber, Sabine; Omann, Markus; Zeilinger, Susanne

2013-05-16

Eukaryotic organisms employ cell surface receptors such as the seven-transmembrane G protein-coupled receptors (GPCRs) as sensors to connect to the environment. GPCRs react to a variety of extracellular cues and are considered to play central roles in the signal transduction in fungi. Several species of the filamentous ascomycete Trichoderma are potent mycoparasites, i.e. can attack and parasitize other fungi, which turns them into successful bio-fungicides for the protection of plants against fungal phytopathogens. The identification and characterization of GPCRs will provide insights into how Trichoderma communicates with its environment and senses the presence of host fungi. We mined the recently published genomes of the two mycoparasitic biocontrol agents Trichoderma atroviride and Trichoderma virens and compared the identified GPCR-like proteins to those of the saprophyte Trichoderma reesei. Phylogenetic analyses resulted in 14 classes and revealed differences not only among the three Trichoderma species but also between Trichoderma and other fungi. The class comprising proteins of the PAQR family was significantly expanded both in Trichoderma compared to other fungi as well as in the two mycoparasites compared to T. reesei. Expression analysis of the PAQR-encoding genes of the three Trichoderma species revealed that all except one were actually transcribed. Furthermore, the class of receptors with a DUF300 domain was expanded in T. atroviride, and T. virens showed an expansion of PTH11-like receptors compared to T. atroviride and T. reesei. Comparative genome analyses of three Trichoderma species revealed a great diversity of putative GPCRs with genus- and species- specific differences. The expansion of certain classes in the mycoparasites T. atroviride and T. virens is likely to reflect the capability of these fungi to establish various ecological niches and interactions with other organisms such as fungi and plants. These GPCRs consequently represent interesting candidates for future research on the mechanisms underlying mycoparasitism and biocontrol.

Biocontrol of the wheat pathogen Zymoseptoria tritici using cyclic lipopeptides from Bacillus subtilis.

PubMed

Mejri, Samara; Siah, Ali; Coutte, François; Magnin-Robert, Maryline; Randoux, Béatrice; Tisserant, Benoit; Krier, François; Jacques, Philippe; Reignault, Philippe; Halama, Patrice

2017-06-21

Innovation toward ecofriendly plant protection products compatible with sustainable agriculture and healthy food is today strongly encouraged. Here, we assessed the biocontrol activity of three cyclic lipopeptides from Bacillus subtilis (mycosubtilin, M; surfactin, S; fengycin, F) and two mixtures (M + S and M + S + F) on wheat against Zymoseptoria tritici, the main pathogen on this crop. Foliar application of these biomolecules at a 100-mg L -1 concentration on the wheat cultivars Dinosor and Alixan, 2 days before fungal inoculation, provided significant reductions of disease severity. The best protection levels were recorded with the M-containing formulations (up to 82% disease reduction with M + S on Dinosor), while S and F treatments resulted in lower but significant disease reductions. In vitro and in planta investigations revealed that M-based formulations inhibit fungal growth, with half-maximal inhibitory concentrations of 1.4 mg L -1 for both M and M + S and 4.5 mg L -1 for M + S + F, thus revealing that the observed efficacy of these products may rely mainly on antifungal property. By contrast, S and F had no direct activity on the pathogen, hence suggesting that these lipopeptides act on wheat against Z. tritici as resistance inducers rather than as biofungicides. This study highlighted the efficacy of several lipopeptides from B. subtilis to biocontrol Z. tritici through likely distinct and biomolecule-dependent modes of action.

Population dynamics of Aspergillus flavus following biocontrol treatment of corn

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus is a fungal pathogen of many agronomically important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, North Carolina, over a period of two years. The field was planted in 2010 and plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Af...

Production of trichodiene by Trichoderma harzianum alters the perception of this biocontrol strain by plants and antagonized fungi

USDA-ARS?s Scientific Manuscript database

Trichothecenes are phytotoxic sesquiterpenoid compounds of fungal origin which can act as virulence factors in plant diseases. Harzianum A (HA) is a non-phytotoxic trichothecene produced by Trichoderma arundinaceum. The first step in the biosynthesis of HA is the conversion of farnesyl diphosphate t...

Proposal to conserve the name Talaromyces over Lasioderma

USDA-ARS?s Scientific Manuscript database

Lasioderma Mont., in Annls Sci. Nat., Bot., sér. 3, 4 (no. 96): 364. 1845, threatens the use of Talaromyces C.R. Benj., in Mycologia 47: 681. 1955 because the two names appear to refer to the same fungal genus. Talaromyces is composed of nearly 70 species important in medicine, biocontrol of root ro...

A proteomics approach to study synergistic and antagonistic interactions of the fungal-bacterial consortium Fusarium oxysporum wild-type MSA 35.

PubMed

Moretti, Marino; Grunau, Alexander; Minerdi, Daniela; Gehrig, Peter; Roschitzki, Bernd; Eberl, Leo; Garibaldi, Angelo; Gullino, Maria Lodovica; Riedel, Kathrin

2010-09-01

Fusarium oxysporum is an important plant pathogen that causes severe damage of many economically important crop species. Various microorganisms have been shown to inhibit this soil-borne plant pathogen, including non-pathogenic F. oxysporum strains. In this study, F. oxysporum wild-type (WT) MSA 35, a biocontrol multispecies consortium that consists of a fungus and numerous rhizobacteria mainly belonging to gamma-proteobacteria, was analyzed by two complementary metaproteomic approaches (2-DE combined with MALDI-Tof/Tof MS and 1-D PAGE combined with LC-ESI-MS/MS) to identify fungal or bacterial factors potentially involved in antagonistic or synergistic interactions between the consortium members. Moreover, the proteome profiles of F. oxysporum WT MSA 35 and its cured counter-part CU MSA 35 (WT treated with antibiotics) were compared with unravel the bacterial impact on consortium functioning. Our study presents the first proteome mapping of an antagonistic F. oxysporum strain and proposes candidate proteins that might play an important role for the biocontrol activity and the close interrelationship between the fungus and its bacterial partners.

Mechanism of H₂O₂-induced oxidative stress regulating viability and biocontrol ability of Rhodotorula glutinis.

PubMed

Chen, Jian; Li, Boqiang; Qin, Guozheng; Tian, Shiping

2015-01-16

The use of antagonistic yeasts to control postharvest pathogens is a promising alternative to fungicides. The effectiveness of the antagonists against fungal pathogens is greatly dependent on their viability, which is usually mediated by reactive oxygen species (ROS). Here, we investigated the effects of H₂O₂-induced oxidative stress on the viability and biocontrol efficacy of Rhodotorula glutinis and, using flow cytometric analysis, observed the changes of ROS accumulation and apoptosis in the yeast cells with or without H₂O₂ treatment. We found that the viability of R. glutinis decreased in a time- and dose-dependent manner under H₂O₂-induced oxidative stress. Compared to the control, yeast cells exposed to oxidative stress exhibited more accumulation of ROS and higher levels of protein oxidative damage, but showed lower efficacy for biocontrol of Penicillium expansum causing blue mold rot on peach fruit. The results indicate that apoptosis is a main cause of the cell viability loss in R. glutinis, which is attributed to ROS accumulation under oxidative stress. These findings offer a plausible explanation that oxidative stress affects biocontrol efficacy of R. glutinis via regulating its viability and cell apoptosis. Copyright © 2014 Elsevier B.V. All rights reserved.

Polyamine is a critical determinant of Pseudomonas chlororaphis O6 for GacS-dependent bacterial cell growth and biocontrol capacity.

PubMed

Park, Ju Yeon; Kang, Beom Ryong; Ryu, Choong-Min; Anderson, Anne J; Kim, Young Cheol

2018-05-01

The Gac/Rsm network regulates, at the transcriptional level, many beneficial traits in biocontrol-active pseudomonads. In this study, we used Phenotype MicroArrays, followed by specific growth studies and mutational analysis, to understand how catabolism is regulated by this sensor kinase system in the biocontrol isolate Pseudomonas chlororaphis O6. The growth of a gacS mutant was decreased significantly relative to that of the wild-type on ornithine and arginine, and on the precursor of these amino acids, N-acetyl-l-glutamic acid. The gacS mutant also showed reduced production of polyamines. Expression of the genes encoding arginine decarboxylase (speA) and ornithine decarboxylases (speC) was controlled at the transcriptional level by the GacS sensor of P. chlororaphis O6. Polyamine production was reduced in the speC mutant, and was eliminated in the speAspeC mutant. The addition of exogenous polyamines to the speAspeC mutant restored the in vitro growth inhibition of two fungal pathogens, as well as the secretion of three biological control-related factors: pyrrolnitrin, protease and siderophore. These results extend our knowledge of the regulation by the Gac/Rsm network in a biocontrol pseudomonad to include polyamine synthesis. Collectively, our studies demonstrate that bacterial polyamines act as important regulators of bacterial cell growth and biocontrol potential. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Streptomyces globosus UAE1, a Potential Effective Biocontrol Agent for Black Scorch Disease in Date Palm Plantations.

PubMed

Saeed, Esam E; Sham, Arjun; Salmin, Zeinab; Abdelmowla, Yasmeen; Iratni, Rabah; El-Tarabily, Khaled; AbuQamar, Synan

2017-01-01

Many fungal diseases affect date palm causing considerable losses in date production worldwide. We found that the fungicide Cidely ® Top inhibited the mycelial growth of the soil-borne pathogenic fungus Thielaviopsis punctulata , the causal agent of black scorch disease of date palm, both in vitro and in vivo . Because the use of biocontrol agents (BCAs) can minimize the impact of pathogen control on economic and environmental concerns related to chemical control, we aimed at testing local actinomycete strains isolated from the rhizosphere soil of healthy date palm cultivated in the United Arab Emirates (UAE) against T. punctulata . The selected isolate can thus be used as a potential agent for integrated disease management programs. In general, the BCA showed antagonism in vitro and in greenhouse experiments against this pathogen. The most promising actinomycete isolate screened showed the highest efficacy against the black scorch disease when applied before or at the same time of inoculation with T. punctulata , compared with BCA or fungicide application after inoculation. The nucleotide sequence and phylogenetic analyses using the 16 S ribosomal RNA gene with other Streptomyces spp. in addition to morphological and cultural characteristics revealed that the isolated UAE strain belongs to Streptomyces globosus UAE1. The antagonistic activity of S. globosus against T. punctulata , was associated with the production by this strain of diffusible antifungal metabolites i.e., metabolites that can inhibit mycelial growth of the pathogen. This was evident in the responses of the vegetative growth of pure cultures of the pathogen when exposed to the culture filtrates of the BCA. Altogether, the pathogenicity tests, disease severity indices and mode of action tests confirmed that the BCA was not only capable of suppressing black scorch disease symptoms, but also could prevent the spread of the pathogen, as a potential practical method to improve disease management in the palm plantations. This is the first report of an actinomycete, naturally occurring in the UAE with the potential for use as a BCA in the management of the black scorch disease of date palms in the region.

How to control bio-slime in condenser cooling system water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freymark, S.

1979-08-01

A number of oxidizing and non-oxidizing biocides are currently used for biocontrol. However, yesterday's solution to slime-fouling problems may not apply today in view of tightening effluent restrictions on chlorine. Thus, selection of biocontrol compounds can not be made indiscriminately. In selecting alternative biocontrol compounds, consideration should be given not only to costs but to effectiveness of the biocide in each particular application, taking into consideration cooling water quality, type of microbiological fouling and discharge restrictions. Thoughtful selection of the biocontrol compound(s), alone or in combination with surface-active agents, is essential for maintaining maximum microbiological control in condenser cooling watermore » systems.« less

CsrB, a noncoding regulatory RNA, is required for BarA-dependent expression of biocontrol traits in Rahnella aquatilis HX2.

PubMed

Mei, Li; Xu, Sanger; Lu, Peng; Lin, Haiping; Guo, Yanbin; Wang, Yongjun

2017-01-01

Rahnella aquatilis is ubiquitous and its certain strains have the applicative potent as a plant growth-promoting rhizobacteria. R. aquatilis HX2 is a biocontrol agent to produce antibacterial substance (ABS) and showed efficient biocontrol against crown gall caused by Agrobacterium vitis on sunflower and grapevine plants. The regulatory network of the ABS production and biocontrol activity is still limited known. In this study, a transposon-mediated mutagenesis strategy was used to investigate the regulators that involved in the biocontrol activity of R. aquatilis HX2. A 366-nt noncoding RNA CsrB was identified in vitro and in vivo, which regulated ABS production and biocontrol activity against crown gall on sunflower plants, respectively. The predicted product of noncoding RNA CsrB contains 14 stem-loop structures and an additional ρ-independent terminator harpin, with 23 characteristic GGA motifs in the loops and other unpaired regions. CsrB is required for ABS production and biocontrol activity in the biocontrol regulation by a two-component regulatory system BarA/UvrY in R. aquatilis HX2. The noncoding RNA CsrB regulates BarA-dependent ABS production and biocontrol activity in R. aquatilis HX2. To the best of our knowledge, this is the first report of noncoding RNA as a regulator for biocontrol function in R. aquatilis.

CsrB, a noncoding regulatory RNA, is required for BarA-dependent expression of biocontrol traits in Rahnella aquatilis HX2

PubMed Central

Lu, Peng; Lin, Haiping; Guo, Yanbin

2017-01-01

Background Rahnella aquatilis is ubiquitous and its certain strains have the applicative potent as a plant growth-promoting rhizobacteria. R. aquatilis HX2 is a biocontrol agent to produce antibacterial substance (ABS) and showed efficient biocontrol against crown gall caused by Agrobacterium vitis on sunflower and grapevine plants. The regulatory network of the ABS production and biocontrol activity is still limited known. Methodology/Principal findings In this study, a transposon-mediated mutagenesis strategy was used to investigate the regulators that involved in the biocontrol activity of R. aquatilis HX2. A 366-nt noncoding RNA CsrB was identified in vitro and in vivo, which regulated ABS production and biocontrol activity against crown gall on sunflower plants, respectively. The predicted product of noncoding RNA CsrB contains 14 stem-loop structures and an additional ρ-independent terminator harpin, with 23 characteristic GGA motifs in the loops and other unpaired regions. CsrB is required for ABS production and biocontrol activity in the biocontrol regulation by a two-component regulatory system BarA/UvrY in R. aquatilis HX2. Conclusion/Significance The noncoding RNA CsrB regulates BarA-dependent ABS production and biocontrol activity in R. aquatilis HX2. To the best of our knowledge, this is the first report of noncoding RNA as a regulator for biocontrol function in R. aquatilis. PMID:29091941

Optimization of storage condition for maintaining long-term viability of nematophagous fungus Esteya vermicola as biocontrol agent against pinewood nematode.

PubMed

Xue, Jian Jie; Hou, Jin Gang; Zhang, Yong An; Wang, Chun Yan; Wang, Zhen; Yu, Jiao Jiao; Wang, Yun Bo; Wang, Yu Zhu; Wang, Qing Hua; Sung, Chang Keun

2014-11-01

The fungus, Esteya vermicola has been proposed as biocontrol agent against pine wilting disease caused by Bursaphelenchus xylophilus. In this study, we reported the effects of temperature and different additives on the viability and biocontrol efficacy of E. vermicola formulated by alginate-clay. The viability of the E. vermicola formulation was determined for six consecutive months at temperature ranged from -70 to 25 °C. The fresh conidia without any treatment were used as control. Under the optimal storage conditions with E. vermicola alginate-clay formulation, the results suggested that E. vermicola alginate-clay formulation with a long shelf life could be a non-vacuum-packed formulation that contains 2 % sodium alginate and 5 % clay at 4 °C. Three conidial formulations prepared with additives of 15 % glycerol, 0.5 % yeast extract and 0.5 % herbal extraction, respectively significantly improved the shelf life. In addition, these tested formulations retained the same biocontrol efficacy as the fresh conidial against pinewood nematode. This study provided a tractable and low-cost method to preserve the shelf life of E. vermicola.

Improvement of a dry formulation of Pseudomonas fluorescens EPS62e for fire blight disease biocontrol by combination of culture osmoadaptation with a freeze-drying lyoprotectant.

PubMed

Cabrefiga, J; Francés, J; Montesinos, E; Bonaterra, A

2014-10-01

To study the effect of lyoprotectants and osmoadaptation on viability of Pseudomonas fluorescens EPS62e during freeze-drying and storage and to evaluate the formulation in terms of efficacy in biocontrol and fitness on pear flowers. A wettable powder formulation of a biocontrol agent of fire blight was optimized by means of lyoprotectants and culture osmoadaptation. Freeze-drying was used to obtain dehydrated cells, and the best viability (70% of survival) was obtained using lactose as lyoprotectant. Survival during lyophilization was additionally improved using physiological adaptation of cells during cultivation under salt-amended medium (osmoadaptation). The procedure increased the survival of cells after freeze-drying attaining viability values close to a 100% in the lactose-formulated product (3 × 10(11) CFU g(-1) ), and through the storage period of 1 year at 4°C. The dry formulation showed also an improved biocontrol efficacy and survival of EPS62e on pear flowers under low relative humidity conditions. Cell viability after freeze-drying was improved using lactose as lyoprotectant combined with a procedure of osmoadaptation during cultivation. The powder-formulated product remained active for 12 months and retained biocontrol levels similar to that of fresh cells. The formulation showed an improved survival of EPS62e on flowers and an increase of the efficacy of biocontrol of fire blight at low relative humidity. The results have a potential value for commercial application in biocontrol agents not only of fire blight but also of other plant diseases. © 2014 The Society for Applied Microbiology.

Impacts of biological control and invasive species on a non-target native Hawaiian insect.

PubMed

Johnson, M Tracy; Follett, Peter A; Taylor, Andrew D; Jones, Vincent P

2005-02-01

The potential for classical biological control to cause unintended harm to native species was evaluated in the case of the endemic Hawaiian koa bug, Coleotichus blackburniae White (Hemiptera: Scutelleridae), and parasitoids introduced to Hawaii for control of an agricultural pest, the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae). Parasitism of C. blackburniae eggs, nymphs and adults by biocontrol agents was quantified across a wide range of habitats and compared to other sources of mortality. Egg mortality due to the biocontrol agent Trissolcus basalis Wollaston (Hymenoptera: Scelionidae) was low (maximum 26%) and confined to elevations below 500 m on a single host plant. Predation, mainly by alien spiders and ants, was the greatest source of egg mortality (maximum 87%). Parasitism of adult C. blackburniae by the biocontrol agent Trichopoda pilipes (F.) (Diptera: Tachinidae) was near zero at 21 of 24 sites surveyed. Three sites with high bug density had higher levels of T. pilipes parasitism, reaching maxima of 70% among adult female bugs, 100% among males and 50% among fifth instars. Male-biased parasitism indicated that T. pilipes is adapted to using male aggregation pheromone for finding C. blackburniae hosts. The relative impacts of biocontrol agents and other sources of mortality were compared using life tables. Invasive species, particularly generalist egg predators, had the greatest impacts on C. blackburniae populations. Effects of intentionally introduced parasitoids were relatively minor, although the tachinid T. pilipes showed potential for large impacts at individual sites. In retrospect, non-target attacks by biological control agents on C. blackburniae were predictable, but the environmental range and magnitude of impacts would have been difficult to foresee.

Assessing effects of the entomopathogenic fungus Metarhizium brunneum on soil microbial communities in Agriotes spp. biological pest control.

PubMed

Mayerhofer, Johanna; Eckard, Sonja; Hartmann, Martin; Grabenweger, Giselher; Widmer, Franco; Leuchtmann, Adrian; Enkerli, Jürg

2017-10-01

The release of large quantities of microorganisms to soil for purposes such as pest control or plant growth promotion may affect the indigenous soil microbial communities. In our study, we investigated potential effects of Metarhizium brunneum ART2825 on soil fungi and prokaryota in bulk soil using high-throughput sequencing of ribosomal markers. Different formulations of this strain, and combinations of the fungus with garlic as efficacy-enhancing agent, were tested over 4 months in a pot and a field experiment carried out for biological control of Agriotes spp. in potatoes. A biocontrol effect was observed only in the pot experiment, i.e. the application of FCBK resulted in 77% efficacy. Colony counts combined with genotyping and marker sequence abundance confirmed the successful establishment of the applied strain. Only the formulated applied strain caused small shifts in fungal communities in the pot experiment. Treatment effects were in the same range as the effects caused by barley kernels, the carrier of the FCBK formulation and temporal effects. Garlic treatments and time affected prokaryotic communities. In the field experiment, only spatial differences affected fungal and prokaryotic communities. Our findings suggest that M. brunneum may not adversely affect soil microbial communities. © FEMS 2017.

Trichoderma harzianum might impact phosphorus transport by arbuscular mycorrhizal fungi.

PubMed

De Jaeger, Nathalie; de la Providencia, Ivan E; de Boulois, Hervé Dupré; Declerck, Stéphane

2011-09-01

Trichoderma sp. is a biocontrol agent active against plant pathogens via mechanisms such as mycoparasitism. Recently, it was demonstrated that Trichoderma harzianum was able to parasitize the mycelium of an arbuscular mycorrhizal (AM) fungus, thus affecting its viability. Here, we question whether this mycoparasitism may reduce the capacity of Glomus sp. to transport phosphorus ((33)P) to its host plant in an in vitro culture system. (33)P was measured in the plant and in the fungal mycelium in the presence/absence of T. harzianum. The viability and metabolic activity of the extraradical mycelium was measured via succinate dehydrogenase and alkaline phosphatase staining. Our study demonstrated an increased uptake of (33)P by the AM fungus in the presence of T. harzianum, possibly related to a stress reaction caused by mycoparasitism. In addition, the disruption of AM extraradical hyphae in the presence of T. harzianum affected the (33)P translocation within the AM fungal mycelium and consequently the transfer of (33)P to the host plant. The effects of T. harzianum on Glomus sp. may thus impact the growth and function of AM fungi and also indirectly plant performance by influencing the source-sink relationship between the two partners of the symbiosis. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Evaluation of antifungal activity of carbonate and bicarbonate salts alone or in combination with biocontrol agents in control of citrus green mold.

PubMed

Zamani, M; Sharifi Tehrani, A; Ali Abadi, A Alizadeh

2007-01-01

The aim of this research was to determine if the attacks of green mold on orange could be reduced by edible salts alone or in combination with biocontrol agent. For this purpose toxicity to Pantoea digitatum and practical use of sodium carbonate (SC), sodium bicarbonate (SBC) and potassium carbonate, and potassium bicarbonate alone or in combination with antagonistic bacteria (Pseudomonas fluorescens isolate PN, Bacillus subtilis isolate VHN, Pantoea agglomerans isolate CA) to control green mold were determined. All were fungistatic. SC and SBC were equal and superior to the other salts for control of green mold on oranges inoculated 6h before treatment and were chosen for subsequent trails under cold storage conditions. The biocontrol agents were found completely tolerant to 3% sodium bicarbonate and sodium carbonate at room temperature; although their culturability was reduced by > 1000-fold after 60 min in 1% other salt solutions. Satisfactory results were also obtained with the combined treatment for control of green mold. A significant increase in biocontrol activity of all isolate was observed when combined with sodium carbonate and sodium bicarbonate. The treatments comprising CA combined with SB was as effective as fungicide treatment. Thus, use of sodium bicarbonate treatment at 3% followed by the antagonist P. agglomerans CA could be an alternative to chemical fungicides for control of green mold on oranges.

Endophytic fungi associated with roots of date palm (Phoenix dactylifera) in coastal dunes.

PubMed

Mohamed Mahmoud, Fadila; Krimi, Zoulikha; Maciá-Vicente, Jose G; Brahim Errahmani, Mohamed; Lopez-Llorca, Luis V

Symbiotic interactions with fungal endophytes are argued to be responsible for the tolerance of plants to some stresses and for their adaptation to natural conditions. In this study we aimed to examine the endophytic fungal diversity associated with roots of date palms growing in coastal dune systems, and to screen this collection of endophytes for potential use as biocontrol agents, for antagonistic activity and mycoparasitism, and as producers of antifungal compounds with potential efficacy against root diseases of date palm. Roots of nine individual date palms growing in three coastal locations in the South-East of Spain (Guardamar, El Carabassí, and San Juan) were selected to isolate endophytic fungi. Isolates were identified on the basis of morphological and/or molecular characters. Five hundred and fifty two endophytic fungi were isolated and assigned to thirty morphological taxa or molecular operational taxonomic units. Most isolates belonged to Ascomycota, and the dominant order was Hypocreales. Fusarium and Clonostachys were the most frequently isolated genera and were present at all sampling sites. Comparisons of the endophytic diversity with previous studies, and their importance in the management of the date palm crops are discussed. This is the first study on the diversity of endophytic fungi associated with roots of date palm. The isolates obtained might constitute a source of biological control agents and biofertilizers for use in crops of this plant. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

USDA-ARS?s Scientific Manuscript database

Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...

A Saccharomyces cerevisiae genome-wide mutant screen for sensitivity to 2,4-diacetylphloroglucinol, a biocontrol antibiotic produced by Pseudomonas fluorescens

USDA-ARS?s Scientific Manuscript database

Strains of Pseudomonas fluorescens that produce the antibiotic 2,4-diacetylphloroglucinol (DAPG) are biocontrol agents of a variety of soilborne pathogens. DAPG is active against a broad spectrum of organisms ranging from bacteria to higher plants. This suggests that the antibiotic may target basic...

Potential role of exoglucanase genes (WaEXG1 and WaEXG2) in the biocontrol activity of Wickerhamomyces anomalous

USDA-ARS?s Scientific Manuscript database

The use of yeasts, including Wickerhamomyces anomalus, as biocontrol agents against fungi responsible for postharvest diseases of fruits and vegetables has been investigated for the past two decades. Among a variety of killer mechanisms, the production of glucanases coded by the genes WaEXG1 and Wa...

Assessment of biocontrol strains for reduction of mycotoxins (aflatoxin and CPA) in maize

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus strains K49, NRRL 21882 (from Afla-Guard®) and AF36 are being developed as biocontrol agents for the control of aflatoxin in maize. In this study, the three non-aflatoxigenic strains were compared to evaluate which is most effective in reducing aflatoxin. Also, we tested these st...

Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast Pichia anomala for aflatoxin reduction

USDA-ARS?s Scientific Manuscript database

Pichia anomala WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of mycotoxin in the food chain...

Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

PubMed

Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

2012-08-01

Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage. Copyright © 2012 Elsevier B.V. All rights reserved.

The vegetative compatibility group to which the US biocontrol agent Aspergillus flavus AF36 belongs is also endemic to Mexico.

PubMed

Ortega-Beltran, A; Grubisha, L C; Callicott, K A; Cotty, P J

2016-04-01

To assess frequencies of the Aspergillus flavus atoxigenic vegetative compatibility group (VCG) YV36, to which the biocontrol agent AF36 belongs, in maize-growing regions of Mexico. Over 3500 A. flavus isolates recovered from maize agroecosystems in four states of Mexico during 2005 through 2008 were subjected to vegetative compatibility analyses based on nitrate nonutilizing mutants. Results revealed that 59 (1·6%) isolates belong to VCG YV36. All 59 isolates had the MAT1-2 idiomorph at the mating-type locus and the single nucleotide polymorphism in the polyketide synthase gene that confers atoxigenicity. Additional degradation of the aflatoxin gene cluster was detected in three isolates. Microsatellite loci analyses revealed low levels of genetic diversity and no linkage disequilibrium within VCG YV36. The VCG to which the biocontrol agent AF36 belongs, YV36, is also native to Mexico. The North American Free Trade Agreement should facilitate adoption of AF36 for use by Mexico in aflatoxin prevention programs. An USEPA registered biocontrol agent effective at preventing aflatoxin contamination of crops in the US, is also native to Mexico. This should facilitate the path to registration of AF36 as the first biopesticide for aflatoxin mitigation of maize in Mexico. Economic and health benefits to the population of Mexico should result once aflatoxin mitigation programs based on AF36 applications are implemented. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Selection of Streptomyces against soil borne fungal pathogens by a standardized dual culture assay and evaluation of their effects on seed germination and plant growth.

PubMed

Kunova, Andrea; Bonaldi, Maria; Saracchi, Marco; Pizzatti, Cristina; Chen, Xiaoyulong; Cortesi, Paolo

2016-11-09

In the search for new natural resources for crop protection, streptomycetes are gaining interest in agriculture as plant growth promoting bacteria and/or biological control agents. Because of their peculiar life cycle, in which the production of secondary metabolites is synchronized with the development of aerial hyphae and sporulation, the commonly used methods to screen for bacterial antagonists need to be adapted. The dual culture assay was standardized in terms of inoculation timing of Streptomyces antagonist and pathogen, and growth rate of different fungal pathogens. In case of fast-growing fungi, inoculation of the antagonist 2 or 3 days prior to the pathogen resulted in significantly stronger inhibition of mycelium growth. One hundred and thirty Streptomyces strains were evaluated against six destructive soil borne pathogens. The activity of strains varied from broad-spectrum to highly specific inhibition of individual pathogens. All strains inhibited at least one tested pathogen. Three strains, which combined the largest broad-spectrum with the highest inhibition activity, were selected for further characterization with four vegetable species. All of them were able to colonize seed surface of all tested vegetable crops. They mostly improved radicle and hypocotyl growth in vitro, although no statistically significant enhancement of biomass weight was observed in vivo. Occasionally, transient negative effects on germination and plant growth were observed. The adapted dual culture assay allowed us to compare the inhibition of individual Streptomyces strains against six fungal soil borne pathogens. The best selected strains were able to colonize the four vegetable crops and have a potential to be developed into biocontrol products. Although they occasionally negatively influenced plant growth, these effects did not persist during the further development. Additional in vivo studies are needed to confirm their potential as biological control or plant growth promoting agents.

Endophytic Trichoderma gamsii YIM PH30019: a promising biocontrol agent with hyperosmolar, mycoparasitism, and antagonistic activities of induced volatile organic compounds on root-rot pathogenic fungi of Panax notoginseng.

PubMed

Chen, Jin-Lian; Sun, Shi-Zhong; Miao, Cui-Ping; Wu, Kai; Chen, You-Wei; Xu, Li-Hua; Guan, Hui-Lin; Zhao, Li-Xing

2016-10-01

Biocontrol agents are regarded as promising and environmental friendly approaches as agrochemicals for phytodiseases that cause serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this study, an endophytic fungus, Trichoderma gamsii YIM PH30019, from healthy Panax notoginseng root was investigated for its biocontrol potential. In vitro detached healthy roots, and pot and field experiments were used to investigate the pathogenicity and biocontrol efficacy of T. gamsii YIM PH30019 to the host plant. The antagonistic mechanisms against test phytopathogens were analyzed using dual culture, scanning electron microscopy, and volatile organic compounds (VOCs). Tolerance to chemical fertilizers was also tested in a series of concentrations. The results indicated that T. gamsii YIM PH30019 was nonpathogenic to the host, presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentrations of up to 20%. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P . notoginseng via production of VOCs. On the basis of gas chromatography-mass spectrometry, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones, etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 was able to improve the seedlings' emergence and protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests. The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.

Fungal endophytes of South China blueberry (Vaccinium dunalianum var. urophyllum).

PubMed

Li, Z-J; Shen, X-Y; Hou, C-L

2016-12-01

A total of 374 fungal endophyte strains were isolated from of Vaccinium dunalianum var. urophyllum (Ericaceae), a well-known cultivated blueberry in southern China. These fungal endophytes could be categorized into 25 morphotypes according to culture characteristics and molecular identification based on the internal transcribed spacer region. All of these isolates belonged to Ascomycota. Jaccard's (Jc) and Sorenson's similarity indices indicated that the species communities from the fruits and branches were closer to each other than to those from leaves. The leaves appeared to host the highest fungal biodiversity, and the fruits displayed the lowest diversity. This study is the first on endophytic fungi isolated from fruits, branches and leaves of blueberry plants. The results contribute to the body of knowledge on the biocontrol of pathogens associated with blueberry and develop the improvement of plant growth. By comparing with the different fungal communities, the leaves appeared to host the highest biodiversity. © 2016 The Society for Applied Microbiology.

Approaches for monitoring the release of Pochonia chlamydosporia var. catenulata, a biocontrol agent of root-knot nematodes.

PubMed

Atkins, Simon D; Hidalgo-Diaz, Leopoldo; Clark, Ian M; Morton, C Oliver; de Oca, Nivian Montes; Gray, Paul A; Kerry, Brian R

2003-02-01

Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. beta-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.

Optimization of a protective medium for freeze-dried Pichia membranifaciens and application of this biocontrol agent on citrus fruit.

PubMed

Niu, X; Deng, L; Zhou, Y; Wang, W; Yao, S; Zeng, K

2016-07-01

To optimize a protective medium for freeze-dried Pichia membranifaciens and to evaluate biocontrol efficacies of agents against blue and green mould and anthracnose in citrus fruit. Based on the screening assays of saccharides and antioxidants, response surface methodology was used to optimize sucrose, sodium glutamate and skim milk to improve viability of freeze-dried Pi. membranifaciens. Biocontrol assays were conducted between fresh and freeze-dried Pi. membranifaciens against Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides in citrus fruit. Solving the regression equation indicated that the optimal protective medium was 6·06% (w/v) sucrose combined with 3·40% (w/v) sodium glutamate and 5·43% (w/v) skim milk. Pi. membranifaciens freeze-dried in the optimal protective medium showed 76·80% viability, and retained biocontrol efficacy against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The optimal protective medium showed more effective protective properties than each of the three protectants used alone. The viability of freeze-dried Pi. membranifaciens finally reached 76·80%. Meanwhile, the biocontrol efficacies showed no significant difference between fresh and freeze-dried yeast against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The results showed the potential value of Pi. membranifaciens CICC 32259 for commercialization. © 2016 The Society for Applied Microbiology.

Fungal Endophyte Diversity and Bioactivity in the Indian Medicinal Plant Ocimum sanctum Linn

PubMed Central

Chowdhary, Kanika; Kaushik, Nutan

2015-01-01

Endophytic mycopopulation isolated from India’s Queen of herbs Tulsi (Ocimum sanctum) were explored and investigated for their diversity and antiphytopathogenic activity against widespread plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani and Fusarium oxysporum. 90 fungal isolates, representing 17 genera were recovered from 313 disease-free and surface sterilised plant segments (leaf and stem tissues) from three different geographic locations (Delhi, Hyderabad and Mukteshwar) during distinct sampling times in consequent years 2010 and 2011 in India. Fungal endophytes were subjected to molecular identification based on rDNA ITS sequence analysis. Plant pathogens such as F. verticillioides, B. maydis, C. coarctatum, R. bataticola, Hypoxylon sp., Diaporthe phaseolorum, Alternaria tenuissima and A. alternata have occurred as endophyte only during second sampling (second sampling in 2011) in the present study. Bi-plot generated by principal component analysis suggested tissue specificity of certain fungal endophytes. Dendrogram revealed species abundance as a function of mean temperature of the location at the time of sampling. Shannon diversity in the first collection is highest in Hyderabad leaf tissues (H' = 1.907) whereas in second collection it was highest from leaf tissues of Delhi (H' = 1.846). Mukteshwar (altitude: 7500 feet) reported least isolation rate in second collection. Nearly 23% of the total fungal isolates were considered as potent biocontrol agent. Hexane extract of M. phaseolina recovered from Hyderabad in first collection demonstrated highest activity against S. sclerotiorum with IC50 value of 0.38 mg/ml. Additionally, its components 2H-pyran-2-one, 5,6-dihydro-6-pentyl and palmitic acid, methyl ester as reported by GC-MS Chromatogram upon evaluation for their antiphytopathogenic activity exhibited IC50 value of 1.002 and 0.662 against respectively S. sclerotiorum indicating their significant role in antiphytopathogenic activity of hexane extract. The production of 2H-pyran-2-one, 5,6-dihydro-6-pentyl from M. phaseolina, an endophytic fungus is being reported for the first time. PMID:26529087

Biocontrol Activity of the Local Strain of Metschnikowia pulcherrima on Different Postharvest Pathogens.

PubMed

Türkel, Sezai; Korukluoğlu, Mihriban; Yavuz, Mümine

2014-01-01

The strains of the yeast Metschnikowia pulcherrima have strong biocontrol activity against various microorganisms. Biocontrol activity of M. pulcherrima largely depends on its iron immobilizing pigment pulcherrimin. Biocontrol activity of pulcherrimin producing strain, M. pulcherrima UMY15, isolated from local vineyards, was tested on different molds that cause food spoilage. M. pulcherrima UMY15 was a very effective biocontrol agent against Penicillium roqueforti, P. italicum, P. expansum, and Aspergillus oryzae in in-vitro plate tests. However, the inhibitory activity of M. pulcherrima UMY15 was less effective on Fusarium sp. and A. niger species in biocontrol assays. In addition, M. pulcherrima UMY15 strain completely inhibited the germination and mycelia growth of A. oryzae, A. parasiticus, and Fusarium sp. spores on artificial wounds of apples when they coinoculated with M. pulcherrima UMY15. Moreover, when coinoculated, M. pulcherrima UMY15 strain also inhibited the growth of P. roqueforti, P. italicum, P. expansum, A. oryzae, Fusarium sp., and Rhizopus sp. in grape juice, indicating that M. pulcherrima UMY15 can be used as a very effective biocontrol yeast against various species of postharvest pathogens, including Penicillium, Aspergillus, Fusarium, and Rhizopus.

Fungal disease dynamics in insect societies: optimal killing rates and the ambivalent effect of high social interaction rates.

PubMed

Novak, Sebastian; Cremer, Sylvia

2015-05-07

Entomopathogenic fungi are potent biocontrol agents that are widely used against insect pests, many of which are social insects. Nevertheless, theoretical investigations of their particular life history are scarce. We develop a model that takes into account the main distinguishing features between traditionally studied diseases and obligate killing pathogens, like the (biocontrol-relevant) insect-pathogenic fungi Metarhizium and Beauveria. First, obligate killing entomopathogenic fungi produce new infectious particles (conidiospores) only after host death and not yet on the living host. Second, the killing rates of entomopathogenic fungi depend strongly on the initial exposure dosage, thus we explicitly consider the pathogen load of individual hosts. Further, we make the model applicable not only to solitary host species, but also to group living species by incorporating social interactions between hosts, like the collective disease defences of insect societies. Our results identify the optimal killing rate for the pathogen that minimises its invasion threshold. Furthermore, we find that the rate of contact between hosts has an ambivalent effect: dense interaction networks between individuals are considered to facilitate disease outbreaks because of increased pathogen transmission. In social insects, this is compensated by their collective disease defences, i.e., social immunity. For the type of pathogens considered here, we show that even without social immunity, high contact rates between live individuals dilute the pathogen in the host colony and hence can reduce individual pathogen loads below disease-causing levels. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selection of lactic acid bacteria to promote an efficient silage fermentation capable of inhibiting the activity of Aspergillus parasiticus and Fusarium gramineraum and mycotoxin production.

PubMed

Dogi, C A; Fochesato, A; Armando, R; Pribull, B; de Souza, M M S; da Silva Coelho, I; Araújo de Melo, D; Dalcero, A; Cavaglieri, L

2013-06-01

To select lactic acid bacteria with potential silage inoculant properties. The bio-control activity against mycotoxicogenic fungi and the presence of antibiotics resistance gene were also evaluated. Lactobacillus rhamnosus RC007 and Lactobacillus plantarum RC009 were selected on the basis of growth rate and efficacy in reducing the pH of maize extract medium; therefore, they were evaluated for their bio-control ability against Fusarium graminearum and Aspergillus parasiticus. Studies on lag phase, growth rate and aflatoxin B1 (AFB1) and zearalenone (ZEA) production were carried out in vitro under different regimes of aw (0·95 and 0·99); pH (4 and 6); temperature (25 and 37°C); and oxygen availability (normal and reduced). Lactobacillus rhamnosus RC007 was able to completely inhibit the F. graminearum growth at all assayed conditions, while Lact. plantarum RC009 only did it at pH 4. Both Lactobacillus strains were able to significantly reduce the A. parasiticus growth rate mainly at 0·99 aw . A decrease in ZEA production was observed as result of Lactobacillus strains -F. graminearum interaction; however, the A. parasiticus- Lact. plantarum interaction resulted in an increased AFB1 production. Lactobacillus rhamnosus RC007 proved to have no genes for resistance to the tested antibiotics. The ability of Lact. rhamnosus RC007 to rapidly drop the pH and to inhibit fungal growth and mycotoxin production and the absence of antibiotic resistance genes shows the potential of its application as inoculant and bio-control agent in animal feed. This study demonstrated the importance of selecting bacteria for silage inoculants not only for the improvement of silage fermentation but also for their effects on mycotoxicogenic fungi and the resulting mycotoxin production due to the risk that they may involve. © 2013 The Society for Applied Microbiology.

The potential for trichogramma releases to suppress tip moth populations in pine plantations

Treesearch

David B. Orr; Charles P.-C Suh; Michael Philip; Kenneth W. McCravy; Gary L. DeBarr

1999-01-01

Because the Nantucket pine tip moth is a native pest, augmentation (mass-release) of native natural enemies may be the most promising method of tip moth biocontrol. The tip moth has several important egg, larval, and pupal parasitoids. Egg parasitoids are most effective as biocontrol agents because they eliminate the host before it reaches a damaging stage....

Seasonal adaptations to day length in ecotypes of Diorhabda spp. (Coleoptera: Chrysomelidae) inform selection of agents against saltcedars (Tamarix spp.)

USDA-ARS?s Scientific Manuscript database

1. Seasonal adaptations to day length often limit the effective range of biocontrol insects. The leaf beetle Diorhabda carinulata was introduced into North America from Fukang, China (latitude 44°N) for the biocontrol of saltcedars (Tamarix spp.), but failed to establish below 38° latitude because o...

Involvement of phenazines and biosurfactants in biocontrol of Pythium myriotylum root rot on cocoyam by Pseudomonas sp. CMR12A

USDA-ARS?s Scientific Manuscript database

Pseudomonas sp. CMR12a was isolated from the rhizosphere of the tropical tuber crop cocoyam and produces both phenazines and cyclic lipopeptide (CLP) biosurfactants. CMR12a was shown to be an efficient biocontrol agent of P. myriotylum on cocoyam. To assess the importance of phenazine and biosurfact...

Immunohistochemical investigation of the necrotropic phase of the fungus Colletotrichum gloeosporioides in the biocontrol of Hemp sesbania (Sesbania exaltata; Papilionaceae)

USDA-ARS?s Scientific Manuscript database

Fungal plant pathogens exert much of their effect on plant cells through alterations in the host cell walls. However, biochemical proof for this change is difficult because of the relatively small number of cells that are affected by the pathogen in the bulk of host tissue. In this study, we examine...

Pyrenophoric acid, a phytotoxic sesquiterpenoid penta-2,4-dienoic acid produced by a potential mycoherbicide, Pyrenophora semeniperda

Treesearch

Marco Masi; Susan Meyer; Alessio Cimmino; Anna Andolfi; Antonio Evidente

2014-01-01

A new phytotoxic sesquiterpenoid penta-2,4- dienoic acid, named pyrenophoric acid, was isolated from solid wheat seed culture of Pyrenophora semeniperda, a fungal pathogen proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum) and other annual bromes. These bromes are serious weeds in winter cereals and also on temperate semiarid rangelands....

Quantifying the associations between fungal endophytes and biocontrol-induced herbivory of invasive purple loosestrife (Lythrum salicaria L.).

PubMed

David, Aaron S; Quiram, Gina L; Sirota, Jennie I; Seabloom, Eric W

2016-01-01

Fungal endophytes are one of several groups of heterotrophic organisms that associate with living plants. The net effects of these groups of organisms on each other and ultimately on their host plants depend in part on how they facilitate or antagonize one another. In this study we quantified the associations between endophyte communities and herbivory induced by a biological control in the invasive Lythrum salicaria at various spatial scales using a culture-based approach. We found positive associations between herbivory damage and endophyte isolation frequency and richness at the site level and weak, positive associations at the leaf level. Herbivory damage was more strongly influenced by processes at the site level than were endophyte isolation frequency and community structure, which were influenced by processes at the plant and leaf levels. Furthermore, endophytic taxa found in low herbivory sites were nested subsets of those taxa found at high herbivory sites. Our findings suggest that endophyte communities of L. salicaria are associated with, and potentially facilitated by, biocontrol-induced herbivory. Quantifying the associations between heterotrophic groups ultimately may lead to a clearer understanding of their complex interactions with plants. © 2016 by The Mycological Society of America.

Regulation of morphogenesis and biocontrol properties in Trichoderma virens by a VELVET protein, Vel1.

PubMed

Mukherjee, Prasun K; Kenerley, Charles M

2010-04-01

Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species.

Regulation of Morphogenesis and Biocontrol Properties in Trichoderma virens by a VELVET Protein, Vel1▿ †

PubMed Central

Mukherjee, Prasun K.; Kenerley, Charles M.

2010-01-01

Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species. PMID:20154111

Interactome analysis of transcriptional coactivator multiprotein bridging factor 1 unveils a yeast AP-1-like transcription factor involved in oxidation tolerance of mycopathogen Beauveria bassiana.

PubMed

Chu, Xin-Ling; Dong, Wei-Xia; Ding, Jin-Li; Feng, Ming-Guang; Ying, Sheng-Hua

2018-02-01

Oxidation tolerance is an important determinant to predict the virulence and biocontrol potential of Beauveria bassiana, a well-known entomopathogenic fungus. As a transcriptional coactivator, multiprotein bridging factor 1 mediates the activity of transcription factor in diverse physiological processes, and its homolog in B. bassiana (BbMBF1) contributes to fungal oxidation tolerance. In this study, the BbMBF1-interactomes under oxidative stress and normal growth condition were deciphered by mass spectrometry integrated with the immunoprecipitation. BbMBF1p factor has a broad interaction with proteins that are involved in various cellular processes, and this interaction is dynamically regulated by oxidative stress. Importantly, a B. bassiana homolog of yeast AP-1-like transcription factor (BbAP-1) was specifically associated with the BbMBF1-interactome under oxidation and significantly contributed to fungal oxidation tolerance. In addition, qPCR analysis revealed that several antioxidant genes are jointly controlled by BbAP-1 and BbMBF1. Conclusively, it is proposed that BbMBF1p protein mediates BbAP-1p factor to transcribe the downstream antioxidant genes in B. bassiana under oxidative stress. This study demonstrates for the first time a proteomic view of the MBF1-interactome in fungi, and presents an initial framework to probe the transcriptional mechanism involved in fungal response to oxidation, which will provide a new strategy to improve the biocontrol efficacy of B. bassiana.

The seven-transmembrane receptor Gpr1 governs processes relevant for the antagonistic interaction of Trichoderma atroviride with its host.

PubMed

Omann, Markus R; Lehner, Sylvia; Escobar Rodríguez, Carolina; Brunner, Kurt; Zeilinger, Susanne

2012-01-01

Mycoparasitic Trichoderma species are applied as biocontrol agents in agriculture to guard plants against fungal diseases. During mycoparasitism, Trichoderma directly interacts with phytopathogenic fungi, preceded by a specific recognition of the host and resulting in its disarming and killing. In various fungal pathogens, including mycoparasites, signalling via heterotrimeric G proteins plays a major role in regulating pathogenicity-related functions. However, the corresponding receptors involved in the recognition of host-derived signals are largely unknown. Functional characterization of Trichoderma atroviride Gpr1 revealed a prominent role of this seven-transmembrane protein of the cAMP-receptor-like family of fungal G-protein-coupled receptors in the antagonistic interaction with the host fungus and governing of mycoparasitism-related processes. Silencing of gpr1 led to an avirulent phenotype accompanied by an inability to attach to host hyphae. Furthermore, gpr1-silenced transformants were unable to respond to the presence of living host fungi with the expression of chitinase- and protease-encoding genes. Addition of exogenous cAMP was able to restore host attachment in gpr1-silenced transformants but could not restore mycoparasitic overgrowth. A search for downstream targets of the signalling pathway(s) involving Gpr1 resulted in the isolation of genes encoding e.g. a member of the cyclin-like superfamily and a small secreted cysteine-rich protein. Although silencing of gpr1 caused defects similar to those of mutants lacking the Tga3 Gα protein, no direct interaction between Gpr1 and Tga3 was observed in a split-ubiquitin two-hybrid assay.

Characterization of a protease produced by a Trichoderma harzianum isolate which controls cocoa plant witches' broom disease

PubMed Central

De Marco, Janice L; Felix, Carlos Roberto

2002-01-01

Background Several Trichoderma strains have been reported to be effective in controlling plant diseases, and the action of fungal hydrolytic enzymes has been considered as the main mechanism involved in the antagonistic process. However, although Trichoderma strains were found to impair development of Crinipellis perniciosa, the causal agent of cocoa plant witches' broom disease, no fungal strain is available for effective control of this disease. We have then undertaken a program of construction of hydrolytic enzyme-overproducing Trichoderma strains aiming improvement of the fungal antagonistic capacity. The protease of an indian Trichoderma isolate showing antagonistic activity against C. perniciosa was purified to homogeneity and characterized for its kinetic properties and action on the phytopathogen cell wall. Results A protease produced by the Trichoderma harzianum isolate 1051 was purified to homogeneity by precipitation with ammonium sulfate followed by hydrophobic chromatography. The molecular mass of this protease as determined by SDS-polyacrylamide gel electrophoresis was about 18.8 kDa. Its N-terminal amino acid sequence shares no homology with any other protease. The purified enzyme substantially affected the cell wall of the phytopathogen C. perniciosa. Western-blotting analysis showed that the enzyme was present in the culture supernatant 24 h after the Trichoderma started to grow in casein-containing liquid medium. Conclusions The capacity of the Trichoderma harzianum protease to hydrolyze the cell wall of C. perniciosa indicates that this enzyme may be actually involved in the antagonistic process between the two fungi. This fact strongly suggest that hydrolytic enzyme over-producing transgenic fungi may show superior biocontrol capacity. PMID:11835696

The seven-transmembrane receptor Gpr1 governs processes relevant for the antagonistic interaction of Trichoderma atroviride with its host

PubMed Central

Omann, Markus R.; Lehner, Sylvia; Escobar Rodríguez, Carolina; Brunner, Kurt

2012-01-01

Mycoparasitic Trichoderma species are applied as biocontrol agents in agriculture to guard plants against fungal diseases. During mycoparasitism, Trichoderma directly interacts with phytopathogenic fungi, preceded by a specific recognition of the host and resulting in its disarming and killing. In various fungal pathogens, including mycoparasites, signalling via heterotrimeric G proteins plays a major role in regulating pathogenicity-related functions. However, the corresponding receptors involved in the recognition of host-derived signals are largely unknown. Functional characterization of Trichoderma atroviride Gpr1 revealed a prominent role of this seven-transmembrane protein of the cAMP-receptor-like family of fungal G-protein-coupled receptors in the antagonistic interaction with the host fungus and governing of mycoparasitism-related processes. Silencing of gpr1 led to an avirulent phenotype accompanied by an inability to attach to host hyphae. Furthermore, gpr1-silenced transformants were unable to respond to the presence of living host fungi with the expression of chitinase- and protease-encoding genes. Addition of exogenous cAMP was able to restore host attachment in gpr1-silenced transformants but could not restore mycoparasitic overgrowth. A search for downstream targets of the signalling pathway(s) involving Gpr1 resulted in the isolation of genes encoding e.g. a member of the cyclin-like superfamily and a small secreted cysteine-rich protein. Although silencing of gpr1 caused defects similar to those of mutants lacking the Tga3 Gα protein, no direct interaction between Gpr1 and Tga3 was observed in a split-ubiquitin two-hybrid assay. PMID:22075023

An Antifungal Exo-α-1,3-Glucanase (AGN13.1) from the Biocontrol Fungus Trichoderma harzianum

PubMed Central

Ait-Lahsen, Hassane; Soler, Andrés; Rey, Manuel; de la Cruz, Jesús; Monte, Enrique; Llobell, Antonio

2001-01-01

Trichoderma harzianum secretes α-1,3-glucanases when it is grown on polysaccharides, fungal cell walls, or autoclaved mycelium as a carbon source (simulated antagonistic conditions). We have purified and characterized one of these enzymes, named AGN13.1. The enzyme was monomeric and slightly basic. AGN13.1 was an exo-type α-1,3-glucanase and showed lytic and antifungal activity against fungal plant pathogens. Northern and Western analyses indicated that AGN13.1 is induced by conditions that simulated antagonism. We propose that AGN13.1 contributes to the antagonistic response of T. harzianum. PMID:11722942

Non-pathogenic Fusarium solani represses the biosynthesis of nematicidal compounds in vitro and reduces the biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

PubMed

Siddiqui, I A; Shaukat, S S

2003-01-01

The aim of the present investigation was to determine the influence of various Fusarium solani strains on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Culture filtrates (CF) of P. fluorescens strain CHA0 and its diacetylphloroglucinol-overproducing derivative CHA0/pME3424 caused substantial mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with the growth medium of F. solani repressed the nematicidal activity of the bacteria. Methanol extract of F. solani CF resulting from Czapek's Dox liquid (CDL) medium without zinc amendment repressed the nematicidal activity of the bacteria while the CF obtained from CDL medium amended with zinc did not. Conidial suspension of F. solani strain Fs5 (repressor strain for the biosynthesis of nematicidal compounds in P. fluorescens) reduced biocontrol potential of the bacterial inoculants against M. javanica in tomato while strain Fs3 (non-repressor) did not. Fusarium solani strains with increased nematicidal activity repress the biosynthesis of nematicidal compounds by P. fluorescens strains in vitro and greatly alter its biocontrol efficacy against root-knot nematode under natural conditions. Fusarium solani strains are distributed worldwide and found in almost all the agricultural fields which suggest that some mycotoxin-producing strains will also be found in almost any soil sample taken. Besides the suppressive effect of these metabolite-producing strains on the production of nematicidal compound(s) critical in biocontrol, F. solani strains may also affect the performance of mycotoxin-sensitive biocontrol bacteria effective against plant-parasitic nematodes.

Trichoderma harzianum enhances the production of nematicidal compounds in vitro and improves biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

PubMed

Siddiqui, I A; Shaukat, S S

2004-01-01

To determine the influence of soil-borne fungus Trichoderma harzianum on the biocontrol performance of Pseudomonas fluorescens strain CHA0 and its 2,4-diacetylphloroglucinol (DAPG) overproducing derivative CHA0/pME3424 against Meloidogyne javanica. Amendment of the culture filtrate (CF) or methanol extract of the CF of a T. harzianum strain Th6 to P. fluorescens growth medium enhanced the production of nematicidal compound(s) by bacterial inoculants in vitro. In addition, bacteria overwhelmingly expressed phl'-'lacZ reporter gene when the medium was amended with CF of T. harzianum. Pseudomonas fluorescens and T. harzianum applied together in unsterilized sandy loam soil caused greater reduction in nematode population densities in tomato roots. Trichoderma harzianum improves root-knot nematode biocontrol by the antagonistic rhizobacterium P. fluorescens both in vitro and under glasshouse conditions. The synergistic effect of T. harzianum on the production of nematicidal compound(s) critical in biocontrol may improve the efficacy of biocontrol bacteria against plant-parasitic nematodes. Considering the inconsistent performance of the biocontrol agents under field conditions, application of a mixture of compatible T. harzianum and P. fluorescens would more closely mimic the natural situation and might broaden the spectrum of biocontrol activity with enhanced efficacy and reliability of control.

Protection of groundnut plants from rust disease by application of glucan isolated from a biocontrol agent Acremonium obclavatum.

PubMed

Sathiyabama, M; Balasubramanian, R

2018-05-01

Prior treatment of groundnut leaves with glucan isolated from a biocontrol agent, Acremonium obclavatum, protected against the rust disease. Glucan treated leaves showed increased levels of chitinase and β-1,3-glucanase in the apoplastic fluid. An increase in endogenous levels of salicylic acid also was observed in treated leaves. Treated leaves also showed a significant reduction in rust disease development in groundnut leaves. Enhanced activities of glucanohydrolases of treated groundnut leaves might have affected the biotrophic rust pathogen, which is known to colonize in the apoplastic spaces. Copyright © 2018 Elsevier B.V. All rights reserved.

Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

PubMed Central

Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

2015-01-01

Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

United States Department of Agriculture-Agricultural Research Service research programs on microbes for management of plant-parasitic nematodes.

PubMed

Meyer, Susan L F

2003-01-01

Restrictions on the use of conventional nematicides have increased the need for new methods of managing plant-parasitic nematodes. Consequently, nematode-antagonistic microbes, and active compounds produced by such organisms, are being explored as potential additions to management practices. Programs in this area at the USDA Agricultural Research Service investigate applied biocontrol agents, naturally occurring beneficial soil microbes and natural compounds. Specific research topics include use of plant growth-promoting rhizobacteria and cultural practices for management of root-knot and ring nematodes, determination of management strategies that enhance activity of naturally occurring Pasteuria species (bacterial obligate parasites of nematodes), studies on interactions between biocontrol bacteria and bacterial-feeding nematodes, and screening of microbes for compounds active against plant-parasitic nematodes. Some studies involve biocontrol agents that are active against nematodes and soil-borne plant-pathogenic fungi, or combinations of beneficial bacteria and fungi, to manage a spectrum of plant diseases or to increase efficacy over a broader range of environmental conditions. Effective methods or agents identified in the research programs are investigated as additions to existing management systems for plant-parasitic nematodes.

Exploring the evolutionary ecology of fungal endophytes in agricultural systems: using functional traits to reveal mechanisms in community processes

PubMed Central

Saunders, Megan; Glenn, Anthony E; Kohn, Linda M

2010-01-01

All plants, including crop species, harbor a community of fungal endophyte species, yet we know little about the biotic factors that are important in endophyte community assembly. We suggest that the most direct route to understanding the mechanisms underlying community assembly is through the study of functional trait variation in the host and its fungal consortium. We review studies on crop endophytes that investigate plant and fungal traits likely to be important in endophyte community processes. We focus on approaches that could speed detection of general trends in endophyte community assembly: (i) use of the ‘assembly rules’ concept to identify specific mechanisms that influence endophyte community dynamics, (ii) measurement of functional trait variation in plants and fungi to better understand endophyte community processes and plant–fungal interactions, and (iii) investigation of microbe–microbe interactions, and fungal traits that mediate them. This approach is well suited for research in agricultural systems, where pair-wise host–fungus interactions and mechanisms of fungal–fungal competition have frequently been described. Areas for consideration include the possibility that human manipulation of crop phenotype and deployment of fungal biocontrol species can significantly influence endophyte community assembly. Evaluation of endophyte assembly rules may help to fine-tune crop management strategies. PMID:25567944

Quorum sensing is a key regulator for the antifungal and biocontrol activity of chitinase-producing Chromobacterium sp. C61.

PubMed

Kim, In Seon; Yang, Si Young; Park, Seur Kee; Kim, Young Cheol

2017-01-01

Chromobacterium sp. strain C61 has strong biocontrol activity; however, the genetic and biochemical determinants of its plant disease suppression activity are not well understood. Here, we report the identification and characterization of two new determinants of its biocontrol activity. Transposon mutagenesis was used to identify mutants that were deficient in fungal suppression. One of these mutants had an insertion in a homologue of depD, a structural gene in the dep operon, that encodes a protein involved in non-ribosomal peptide synthesis. In the second mutant, the insertion was in a homologue of the luxI gene, which encodes a homoserine lactone synthase. The luxI - and depD - mutants had no antifungal activity in vitro and a dramatically reduced capacity to suppress various plant diseases in planta. Antifungal production and biocontrol were restored by complementation of the luxI - mutant. Other phenotypes associated with effective biological control, including motility and lytic enzyme secretion, were also affected by the luxI mutation. Biochemical analysis of ethyl acetate extracts of culture filtrates of the mutant and wild-type strains showed that a key antifungal compound, chromobactomycin, was produced by wild-type C61 and the complemented luxI - mutant, but not by the luxI - or depD - mutant. These data suggest that multiple biocontrol-related phenotypes are regulated by homoserine lactones in C61. Thus, quorum sensing plays an essential role in the biological control potential of diverse bacterial lineages. © 2016 BSPP and John Wiley & Sons Ltd.

Mining the Volatilomes of Plant-Associated Microbiota for New Biocontrol Solutions

PubMed Central

Bailly, Aurélien; Weisskopf, Laure

2017-01-01

Microbial lifeforms associated with land plants represent a rich source for crop growth- and health-promoting microorganisms and biocontrol agents. Volatile organic compounds (VOCs) produced by the plant microbiota have been demonstrated to elicit plant defenses and inhibit the growth and development of numerous plant pathogens. Therefore, these molecules are prospective alternatives to synthetic pesticides and the determination of their bioactivities against plant threats could contribute to the development of control strategies for sustainable agriculture. In our previous study we investigated the inhibitory impact of volatiles emitted by Pseudomonas species isolated from a potato field against the late blight-causing agent Phytophthora infestans. Besides the well-documented emission of hydrogen cyanide, other Pseudomonas VOCs impeded P. infestans mycelial growth and sporangia germination. Current advances in the field support the emerging concept that the microbial volatilome contains unexploited, eco-friendly chemical resources that could help select for efficient biocontrol strategies and lead to a greener chemical disease management in the field. PMID:28890716

Endospore production allows using spray-drying as a possible formulation system of the biocontrol agent Bacillus subtilis CPA-8.

PubMed

Yánez-Mendizabal, V; Viñas, I; Usall, J; Cañamás, T; Teixidó, N

2012-04-01

The role of endospore production by Bacillus subtilis CPA-8 on survival during spray-drying was investigated by comparison with a non-spore-forming biocontrol agent Pantoea agglomerans CPA-2. Endospore formation promoted heat resistance in CPA-8 depending on growth time (72 h cultures were more resistant than 24 h ones). The survival of CPA-8 and CPA-2 after spray-drying was determined after being grown in optimised media for 24 and 72 h. Spray-dried 72 h CPA-8 had the best survival (32%), while CPA-2 viability was less than 2%. CPA-8 survival directly related with its ability to produce endospores. Spray-dried CPA-8 reduced Monilinia fructicola conidia germination similarly to fresh cells, demonstrating that spray-drying did not adversely affect biocontrol efficacy. Endospore production thus improves CPA-8 resistance to spray-drying. These results can provide a reliable basis for optimising of the spray-drying formulation process for CPA-8 and other microorganisms.

Mining the Volatilomes of Plant-Associated Microbiota for New Biocontrol Solutions.

PubMed

Bailly, Aurélien; Weisskopf, Laure

2017-01-01

Microbial lifeforms associated with land plants represent a rich source for crop growth- and health-promoting microorganisms and biocontrol agents. Volatile organic compounds (VOCs) produced by the plant microbiota have been demonstrated to elicit plant defenses and inhibit the growth and development of numerous plant pathogens. Therefore, these molecules are prospective alternatives to synthetic pesticides and the determination of their bioactivities against plant threats could contribute to the development of control strategies for sustainable agriculture. In our previous study we investigated the inhibitory impact of volatiles emitted by Pseudomonas species isolated from a potato field against the late blight-causing agent Phytophthora infestans . Besides the well-documented emission of hydrogen cyanide, other Pseudomonas VOCs impeded P. infestans mycelial growth and sporangia germination. Current advances in the field support the emerging concept that the microbial volatilome contains unexploited, eco-friendly chemical resources that could help select for efficient biocontrol strategies and lead to a greener chemical disease management in the field.

Symbiotic performance and induction of systemic resistance against Cercospora sojina in soybean plants co-inoculated with Bacillus sp. CHEP5 and Bradyrhizobium japonicum E109.

PubMed

Tonelli, María Laura; Magallanes-Noguera, C; Fabra, A

2017-11-01

Soybean is an economically very important crop throughout the word and particularly in Argentina. Soybean yield may be affected by many factors such as the lack of some essential nutrients or pathogens attack. In this work we demonstrated that the co-inoculation of the native biocontrol bacterium Bacillus sp. CHEP5 which induces resistance against Cercospora sojina in soybean and the nitrogen fixing strain Bradyrhizobium japonicum E109, was more effective in reducing frog leaf spot severity than the inoculation of the biocontrol agent alone. Probably, this is related with the increase in the ability to form biofilm when both bacteria are growing together. Furthermore, Bacillus sp. CHEP5 inoculation did not affect Bradyrhizobium japonicum E109 symbiotic behavior and flavonoids composition of root exudates in pathogen challenged plants. These results suggest that co-inoculation of plants with rhizobia and biocontrol agents could be a strategy to improve soybean production in a sustainable system.

A novel L-amino acid oxidase from Trichoderma harzianum ETS 323 associated with antagonism of Rhizoctonia solani.

PubMed

Yang, Chia-Ann; Cheng, Chi-Hua; Lo, Chaur-Tsuen; Liu, Shu-Ying; Lee, Jeng-Woei; Peng, Kou-Cheng

2011-05-11

Trichoderma spp. are used as biocontrol agents against phytopathogens such as Rhizoctonia solani, but their biocontrol mechanisms are poorly understood. A novel L-amino oxidase (Th-LAAO) was identified from the extracellular proteins of Trichoderma harzianum ETS 323. Here, we show a FAD-binding glycoprotein with the best substrate specificity constant for L-phenylalanine. Although the amino acid sequence of Th-LAAO revealed limited homology (16-24%) to other LAAO members, a highly conserved FAD-binding motif was identified in the N-terminus. Th-LAAO was shown to be a homodimeric protein, but the monomeric form was predominant when grown in the presence of deactivated Rhizoctonia solani. Furthermore, in vitro assays demonstrated that Th-LAAO had an antagonistic effect against Rhizoctonia solani and a stimulatory one on hyphal density and sporulation in T. harzianum ETS 323. These findings further our understanding of T. harzianum as a biocontrol agent and provide insight into the biological function of l-amino acid oxidase.

Wonder world of phages: potential biocontrol agents safeguarding biosphere and health of animals and humans- current scenario and perspectives.

PubMed

Tiwari, Ruchi; Chakraborty, Sandip; Dhama, Kuldeep; Wani, Mohd Yaqoob; Kumar, Amit; Kapoor, Sanjay

2014-02-01

Darwin's theory of natural selection and concept of survival of fittest of Wallace is a universal truth which derives the force of life among all live entities on this biosphere. Issues regarding food safety along with increased drug resistance and emerging zoonotic infections have proved that multidisciplinary efforts are in demand for human and animal welfare. This has led to development of various novel therapies the list of which remains incomplete without mentioning about phages. Homologous and non-homologous recombination along with point mutation and addition of new genes play role in their evolution. The rapid emergence of the antibiotic resistant strains of bacteria have created keen interest in finding necessary alternatives to check microbial infections and there comes the importance of phages. Phages kill the bacteria either by lysis or by releasing holins. Bacteriophages; the viruses that live on bacteria are nowadays considered as the best biocontrol agents. They are used as replacers of antibiotics; food industry promoter; guard of aquatic life as well as of plants; pre-slaughter treatment agents; Generally Recognized As Safe (GRAS) food additives; Typing agent of bacteria; active tool of super bug therapy; in post harvest crops and food and during post infection and also to combat intracellular pathogens viz. Mycobacteria and Mycoplasma. Cyanophages/phycophages are particularly useful in controlling blooms produced by various genera of algae and cyanobacteria. By performing centrifugation studies and based on electron microscopy certain virus like particles containing ds RNA have been confirmed as mycophages. They are well proven as threat to pathogenic fungi (both fungal hyphae and yeast). Those that infect yeasts are called zymophages. Virophages have exquisite specificity for their viral host, hence can extensively be used for genetic studies and can also act as evolutionary link. After the discovery of very first virophage till now, a total of 3 virophages have been discovered including the Sputnik virophages that are used to study genetic recombination. Virophages also find their application in antiviral therapy; as engineer of ecological system etc. In brief, present review deals with various dimensions of these beneficial viruses that are being used and can be successfully used in future for safeguarding biosphere including animal and human health.

Potential Alternatives to Classical Biocontrol: Using Native Agents in Invaded Habitats and Genetically Engineered Sterile Cultivars for Invasive Plant Management

Treesearch

ShiLi Miao; Yi Li; Qinfeng Guo; Hua Yu; JiangQing Ding; et al.

2012-01-01

The development of an effective approach to control and eradication of invasive species has become a major challenge to scientists, managers, and society. Biocontrol has been widely utilized to control exotic plants in the past few decades with some degree of sucess. However, there have been an increasing number of controversies pertaining to this approach, largely...

Mitotic stability and nuclear inheritance of integrated viral cDNA in engineered hypovirulent strains of the chestnut blight fungus.

PubMed Central

Chen, B; Choi, G H; Nuss, D L

1993-01-01

Transmissible hypovirulence is a novel form of biological control in which virulence of a fungal pathogen is attenuated by an endogenous RNA virus. The feasibility of engineering hypovirulence was recently demonstrated by transformation of the chestnut blight fungus, Cryphonectria parasitica, with a full-length cDNA copy of a hypovirulence-associated viral RNA. Engineered hypovirulent transformants were found to contain both a chromsomally integrated cDNA copy of the viral genome and a resurrected cytoplasmically replicating double-stranded RNA form. We now report stable maintenance of integrated viral cDNA through repeated rounds of asexual sporulation and passages on host plant tissue. We also demonstrate stable nuclear inheritance of the integrated viral cDNA and resurrection of the cytoplasmic viral double-stranded RNA form in progeny resulting from the mating of an engineered hypovirulent C. parasitica strain and a vegetatively incompatible virulent strain. Mitotic stability of the viral cDNA ensures highly efficient transmission of the hypovirulence phenotype through conidia. Meiotic transmission, a mode not observed for natural hypovirulent strains, introduces virus into ascospore progeny representing a spectrum of vegetative compatibility groups, thereby circumventing barriers to anastomosis-mediated transmission imposed by the fungal vegetative incompatibility system. These transmission properties significantly enhance the potential of engineered hypovirulent C. parasitica strains as effective biocontrol agents. Images PMID:8344241

The use of wavelength-selective plastic cladding materials in horticulture: understanding of crop and fungal responses through the assessment of biological spectral weighting functions.

PubMed

Paul, Nigel D; Jacobson, Rob J; Taylor, Anna; Wargent, Jason J; Moore, Jason P

2005-01-01

Plant responses to light spectral quality can be exploited to deliver a range of agronomically desirable end points in protected crops. This can be achieved using plastics with specific spectral properties as crop covers. We have studied the responses of a range of crops to plastics that have either (a) increased transmission of UV compared with standard horticultural covers, (b) decreased transmission of UV or (c) increased the ratio of red (R) : far-red (FR) radiation. Both the UV-transparent and R : FR increasing films reduced leaf area and biomass, offering potential alternatives to chemical growth regulators. The UV-opaque film increased growth, but while this may be useful in some crops, there were trade-offs with elements of quality, such as pigmentation and taste. UV manipulation may also influence disease control. Increasing UV inhibited not only the pathogenic fungus Botrytis cinerea but also the disease biocontrol agent Trichoderma harzianum. Unlike B. cinerea, T. harzianum was highly sensitive to UV-A radiation. These fungal responses and those for plant growth in the growth room and the field under different plastics are analyzed in terms of alternative biological spectral weighting functions (BSWF). The role of BSWF in assessing general patterns of response to UV modification in horticulture is also discussed.

Insight into the transcriptome of Arthrobotrys conoides using high throughput sequencing.

PubMed

Ramesh, Pandit; Reena, Patel; Amitbikram, Mohapatra; Chaitanya, Joshi; Anju, Kunjadia

2015-12-01

Arthrobotrys conoides is a nematode-trapping fungus belonging to Orbiliales, Ascomycota group, and traps prey nematodes by means of adhesive network. Fungus has a potential to be used as a biocontrol agent against plant parasitic nematodes. In the present study, we characterized the transcriptome of A. conoides using high-throughput sequencing technology and characterized its virulence unigenes. Total 7,255 cDNA contigs with an average length of 425 bp were generated and 6184 (61.81%) transcripts were functionally annotated and characterized. Majority of unigenes were found analogous to the genes of plant pathogenic fungi. A total of 1749 transcripts were found to be orthologous with eukaryotic proteins of KOG database. Several carbohydrate active enzymes and peptidases were identified. We also analyzed classically and nonclassically secreted proteins and confirmed by BLASTP against fungal secretome database. A total of 916 contigs were analogous to 556 unique proteins of Pathogen Host Interaction (PHI) database. Further, we identified 91 unigenes homologous to the database of fungal virulence factor (DFVF). A total of 104 putative protein kinases coding transcripts were identified by BLASTP against KinBase database, which are major players in signaling pathways. This study provides a comprehensive look at the transcriptome of A. conoides and the identified unigenes might have a role in catching and killing prey nematodes by A. conoides. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

PubMed

Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

2015-01-01

One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1

PubMed Central

Smits, Theo H. M.; Rezzonico, Fabio; Kamber, Tim; Blom, Jochen; Goesmann, Alexander; Ishimaru, Carol A.; Frey, Jürg E.; Stockwell, Virginia O.; Duffy, Brion

2011-01-01

Background Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. Principal Findings Genome analysis indicated two major factors contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. Conclusions Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems. PMID:21789243

Isolation of Ralstonia solanacearum-infecting bacteriophages from tomato fields in Chiang Mai, Thailand, and their experimental use as biocontrol agents.

PubMed

Bhunchoth, A; Phironrit, N; Leksomboon, C; Chatchawankanphanich, O; Kotera, S; Narulita, E; Kawasaki, T; Fujie, M; Yamada, T

2015-04-01

To isolate and characterize novel bacteriophages infecting the phytopathogen, Ralstonia solanacearum, and to evaluate them as resources with potential uses in the biocontrol of bacterial wilt. Fourteen phages infecting R. solanacearum were isolated from soil samples collected in Chiang Mai, Thailand. The phages showed different host ranges when tested against 59 R. solanacearum strains isolated from Thailand and Japan. These phages were characterized as nine podoviruses and five myoviruses based on their morphology. Podovirus J2 in combination with another podovirus (φRSB2) lysed host cells very efficiently in contaminated soil. J2 treatment prevented wilting of tomato plants infected with a highly virulent R. solanacearum strain. Treatment with J2 effectively reduced the amount of the bacterial wilt pathogen in contaminated soil and prevented bacterial wilt of tomato in pot experiments. Myovirus J6 possessed jumbo phage features, giving a unique opportunity to study its utilization as a biocontrol agent. As exemplified by J2, the phages isolated in this study represent valuable resources with potential uses in biocontrol of bacterial wilt. A rare jumbo phage J6 served as a valuable subject to understand and utilize this new group of phages. © 2015 The Society for Applied Microbiology.

The ability of a cold-adapted Rhodotorula mucilaginosa strain from Tibet to control blue mold in pear fruit.

PubMed

Hu, Hao; Yan, Fujie; Wilson, Charles; Shen, Qing; Zheng, Xiaodong

2015-12-01

Cold-adapted yeasts were isolated from soil samples collected in Tibet and evaluated as potential biocontrol agents against blue mold (Penicillium expansum) of pear fruit in cold storage. YC1, an isolate identified as Rhodotorula mucilaginosa, was found to exhibit the greatest biocontrol activity among the different isolates that were screened. A washed cell suspension of YC1 exhibited the best biocontrol activity among three different preparations that were used in the current study. A concentration of 10(8) cells/ml reduced the incidence of decay to 35 %, compared to the control where decay incidence was 100 %. A higher intracellular level of trehalose and a higher proportion of polyunsaturated acids present in YC1, was associated with increased the tolerance of this strain to low temperatures, relative to the other strains that were evaluated. The increased tolerance to low temperature allowed the YC1 strain of yeast to more effectively compete for nutrients and space in wounded pear fruit that had been inoculated with spores of P. expansum and placed in cold storage. The present study demonstrated the ability to select cold-adapted yeasts from cold climates and use them as biocontrol agents of postharvest diseases of fruit placed in cold storage.

Differential impact of some Aspergillus species on Meloidogyne javanica biocontrol by Pseudomonas fluorescens strain CHA0.

PubMed

Siddiqui, I A; Shaukat, S S; Khan, A

2004-01-01

The aim was to determine the influence of some Aspergillus species on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Six species of Aspergillus, isolated from the rhizosphere of certain crops, produced a variety of secondary metabolites in vitro. Culture filtrate (CF) obtained from Ps. fluorescens strain CHA0 and its2,4-diacetylphloroglucinol overproducing mutant CHA0/pME3424 grown in King's B liquid medium caused significant mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with CF of A. niger enhanced nematicidal and beta-galactosidase activities of fluorescent pseudomonads while A. quadrilineatus repressed such activities. Methanol or ethyl acetate extracts of the CF of A. niger markedly optimized bacterial efficacy to cause nematode deaths while hexane extract of the fungus had no influence on the nematicidal activity of the bacterial strains. A. niger applied alone or in conjunction with the bacterial inoculants inhibited root-knot nematode galling in tomato. On the other hand, A. quadrilineatus used alone or together with CHA0 did not inhibit nematode galling but when used in combination with strain CHA0/pME3424 did reduce galling intensity. Aspergillus niger enhances the production of nematicidal compounds by Ps. fluorescensin vitro and improves biocontrol potential of the bacterial inoculants in tomato while A. quadrilineatus reduces bacterial performance to suppress root-knot nematodes. Rhizosphere harbours a variety of micro-organisms including bacteria, fungi and viruses. Aspergillus species are ubiquitous in most agricultural soils and generally produce a variety of secondary metabolites. Such metabolites synthesized by Aspergillus species may influence the production of nematicidal agents and subsequent biocontrol performance of the bacterial inoculants against plant-parasitic nematodes. This fact needs to be taken into consideration when using biocontrol strains in an agriculture system.

The biocontrol agent Pseudomonas chlororaphis PA23 primes Brassica napus defenses through distinct gene networks.

PubMed

Duke, Kelly A; Becker, Michael G; Girard, Ian J; Millar, Jenna L; Dilantha Fernando, W G; Belmonte, Mark F; de Kievit, Teresa R

2017-06-19

The biological control agent Pseudomonas chlororaphis PA23 is capable of protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. While we have elucidated bacterial genes and gene products responsible biocontrol, little is known about how the host plant responds to bacterial priming on the leaf surface, including global changes in gene activity in the presence and absence of S. sclerotiorum. Application of PA23 to the aerial surfaces of canola plants reduced the number of S. sclerotiorum lesion-forming petals by 91.1%. RNA sequencing of the host pathogen interface showed that pretreatment with PA23 reduced the number of genes upregulated in response to S. sclerotiorum by 16-fold. By itself, PA23 activated unique defense networks indicative of defense priming. Genes encoding MAMP-triggered immunity receptors detecting flagellin and peptidoglycan were downregulated in PA23 only-treated plants, consistent with post-stimulus desensitization. Downstream, we observed reactive oxygen species (ROS) production involving low levels of H 2 O 2 and overexpression of genes associated with glycerol-3-phosphate (G3P)-mediated systemic acquired resistance (SAR). Leaf chloroplasts exhibited increased thylakoid membrane structures and chlorophyll content, while lipid metabolic processes were upregulated. In addition to directly antagonizing S. sclerotiorum, PA23 primes the plant defense response through induction of unique local and systemic defense networks. This study provides novel insight into the effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as an alternative to chemical pesticides for protection of important crop systems.

Tackling maize fusariosis: in search of Fusarium graminearum biosuppressors.

PubMed

Adeniji, Adetomiwa Ayodele; Babalola, Olubukola Oluranti

2018-06-22

This review presents biocontrol agents employed to alleviate the deleterious effect of the pathogen Fusarium graminearum on maize. The control of this mycotoxigenic phytopathogen remains elusive despite the elaborate research conducted on its detection, identification, and molecular fingerprinting. This could be attributed to the fact that in vitro and greenhouse biocontrol studies on F. graminearum have exceeded the number of field studies done. Furthermore, along with the variances seen among these F. graminearum suppressing biocontrol strains, it is also clear that the majority of research done to tackle F. graminearum outbreaks was on wheat and barley cultivars. Most fusariosis management related to maize targeted other members of Fusarium such as Fusarium verticillioides, with biocontrol strains from the genera Bacillus and Pseudomonas being used frequently in the experiments. We highlight relevant current techniques needed to identify an effective biofungicide for maize fusariosis and recommend alternative approaches to reduce the scarcity of data for indigenous maize field trials.

Characterization of fungal antagonistic bacilli isolated from aerial roots of banyan (Ficus benghalensis) using intact-cell MALDI-TOF mass spectrometry (ICMS).

PubMed

Pathak, K V; Keharia, H

2013-05-01

To characterize fungal antagonistic bacilli isolated from aerial roots of banyan tree and identify the metabolites responsible for their antifungal activity. Seven gram positive, endospore-forming, rod-shaped endophytic bacterial strains exhibiting a broad-spectrum antifungal activity were isolated from the surface-sterilized aerial roots of banyan tree. The isolates designated as K1, A2, A4 and A12 were identified as Bacillus subtilis, whereas isolates A11 and A13 were identified as Bacillus amyloliquefaciens using Biolog Microbial Identification System. The antifungal lipopeptides, surfactins, iturins and fengycins with masses varying in the range from m/z 900 to m/z 1550 could be detected using intact-cell MALDI-TOF mass spectrometry (ICMS). On the basis of mass spectral and carbon source utilization profile, all seven endophytes could be distinguished from each other. Furthermore, ICMS analysis revealed higher extent of heterogeneity among iturins and fengycins produced by B. subtilis K1, correlating well with its higher antifungal activity in comparison with other isolates. Seven fungal antagonistic bacilli were isolated from aerial roots of banyan tree, exhibiting broad spectrum of antifungal activity, among which B. subtilis K1 isolate was found to be most potent. The ICMS analysis revealed that all these isolates produced cyclic lipopeptides belonging to surfactin, iturin and fengycin families and exhibited varying degree of heterogeneity. The endophytes are considered as a potential source of novel bioactive metabolites, and this study describes the potent fungal antagonistic bacilli from aerial roots of banyan tree. The isolates described in this study have a prospective application as biocontrol agents. Also ICMS analysis described in this study for characterization of antifungal metabolites produced by banyan endophytic bacilli may be used as a high throughput tool for screening of microbes producing novel cyclic lipopeptides. © 2013 The Society for Applied Microbiology.

Volatile Substances Produced by Fusarium oxysporum from Coffee Rhizosphere and Other Microbes affect Meloidogyne incognita and Arthrobotrys conoides

PubMed Central

Freire, E. S.; Campos, V. P.; Pinho, R. S. C.; Oliveira, D. F.; Faria, M. R.; Pohlit, A. M.; Noberto, N. P.; Rezende, E. L.; Pfenning, L. H.; Silva, J. R. C.

2012-01-01

Microorganisms produce volatile organic compounds (VOCs) which mediate interactions with other organisms and may be the basis for the development of new methods to control plant-parasitic nematodes that damage coffee plants. In the present work, 35 fungal isolates were isolated from coffee plant rhizosphere, Meloidogyne exigua eggs and egg masses. Most of the fungal isolates belonged to the genus Fusarium and presented in vitro antagonism classified as mutual exclusion and parasitism against the nematode-predator fungus Arthrobotrys conoides (isolated from coffee roots). These results and the stronger activity of VOCs against this fungus by 12 endophytic bacteria may account for the failure of A. conoides to reduce plant-parasitic nematodes in coffee fields. VOCs from 13 fungal isolates caused more than 40% immobility to Meloidogyne incognita second stage juveniles (J2), and those of three isolates (two Fusarium oxysporum isolates and an F. solani isolate) also led to 88-96% J2 mortality. M. incognita J2 infectivity decreased as a function of increased exposure time to F. oxysporum isolate 21 VOCs. Gas chromatography-mass spectrometry (GC-MS) analysis lead to the detection of 38 VOCs produced by F. oxysporum is. 21 culture. Only five were present in amounts above 1% of the total: dioctyl disulfide (it may also be 2-propyldecan-1-ol or 1-(2-hydroxyethoxy) tridecane); caryophyllene; 4-methyl-2,6-di-tert-butylphenol; and acoradiene. One of them was not identified. Volatiles toxic to nematodes make a difference among interacting microorganisms in coffee rhizosphere defining an additional attribute of a biocontrol agent against plant-parasitic nematodes. PMID:23482720

Real-time PCR for detection and quantification of the biocontrol agent Trichoderma atroviride strain SC1 in soil.

PubMed

Savazzini, Federica; Longa, Claudia Maria Oliveira; Pertot, Ilaria; Gessler, Cesare

2008-05-01

Trichoderma (Hypocreales, Ascomycota) is a widespread genus in nature and several Trichoderma species are used in industrial processes and as biocontrol agents against crop diseases. It is very important that the persistence and spread of microorganisms released on purpose into the environment are accurately monitored. Real-time PCR methods for genus/species/strain identification of microorganisms are currently being developed to overcome the difficulties of classical microbiological and enzymatic methods for monitoring these populations. The aim of the present study was to develop and validate a specific real-time PCR-based method for detecting Trichoderma atroviride SC1 in soil. We developed a primer and TaqMan probe set constructed on base mutations in an endochitinase gene. This tool is highly specific for the detection and quantification of the SC1 strain. The limits of detection and quantification calculated from the relative standard deviation were 6000 and 20,000 haploid genome copies per gram of soil. Together with the low throughput time associated with this procedure, which allows the evaluation of many soil samples within a short time period, these results suggest that this method could be successfully used to trace the fate of T. atroviride SC1 applied as an open-field biocontrol agent.

Indirect effects of biocontrol of an invasive riparian plant (Tamarix) alters habitat and reduces herpetofauna abundance

USGS Publications Warehouse

Bateman, H.L.; Merritt, D.M.; Glenn, E.P.; Nagler, P.L.

2014-01-01

The biological control agent (tamarisk leaf beetle, Diorhabda spp.) is actively being used to defoliate exotic saltcedar or tamarisk (Tamarix spp.) in riparian ecosystems in western USA. The Virgin River in Arizona and Nevada is a system where tamarisk leaf beetle populations are spreading. Saltcedar biocontrol, like other control methods, has the potential to affect non-target species. Because amphibians and reptiles respond to vegetation changes in habitat and forage in areas where beetles are active, herpetofauna are model taxa to investigate potential impacts of biocontrol defoliation. Our objectives related herpetofauna abundance to vegetation cover and indices (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI) and timing of biocontrol defoliation. We captured herpetofauna and ground-dwelling arthropods in trap arrays and measured vegetation using remotely sensed images and on-the-ground measurements at 16–21 sites 2 years before (2009–2010) and 2 years following (2011–2012) biocontrol defoliation. Following defoliation, riparian stands (including stands mixed with native and exotic trees and stands of monotypic exotic saltcedar) had significantly lower NDVI and EVI values and fewer captures of marked lizards. Total captures of herpetofauna (toads, lizards, and snakes) were related to higher vegetation cover and sites with a lower proportion of saltcedar. Our results suggest that effects of biocontrol defoliation are likely to be site-specific and depend upon the proportion of native riparian trees established prior to biocontrol introduction and defoliation. The mechanisms by which habitat structure, microclimate, and ultimately vertebrate species are affected by exotic plant biocontrol riparian areas should be a focus of natural-resource managers.

Evidence for rapid evolutionary change in an invasive plant in response to biological control.

PubMed

Stastny, M; Sargent, R D

2017-05-01

We present evidence that populations of an invasive plant species that have become re-associated with a specialist herbivore in the exotic range through biological control have rapidly evolved increased antiherbivore defences compared to populations not exposed to biocontrol. We grew half-sib families of the invasive plant Lythrum salicaria sourced from 17 populations near Ottawa, Canada, that differed in their history of exposure to a biocontrol agent, the specialist beetle Neogalerucella calmariensis. In a glasshouse experiment, we manipulated larval and adult herbivory to examine whether a population's history of biocontrol influenced plant defence and growth. Plants sourced from populations with a history of biocontrol suffered lower defoliation than naïve, previously unexposed populations, strongly suggesting they had evolved higher resistance. Plants from biocontrol-exposed populations were also larger and produced more branches in response to herbivory, regrew faster even in the absence of herbivory and were better at compensating for the impacts of herbivory on growth (i.e. they exhibited increased tolerance). Furthermore, resistance and tolerance were positively correlated among genotypes with a history of biocontrol but not among naïve genotypes. Our findings suggest that biocontrol can rapidly select for increased defences in an invasive plant and may favour a mixed defence strategy of resistance and tolerance without an obvious cost to plant vigour. Although rarely studied, such evolutionary responses in the target species have important implications for the long-term efficacy of biocontrol programmes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Characterization and competitive ability of non-aflatoxigenic Aspergillus flavus isolated from the maize agro-ecosystem in Argentina as potential aflatoxin biocontrol agents.

PubMed

Alaniz Zanon, María Silvina; Clemente, María Paz; Chulze, Sofía Noemí

2018-07-20

Aspergillus flavus is an opportunistic pathogen and may produce aflatoxins in maize, one of the most important crops in Argentina. A promising strategy to reduce aflatoxin accumulation is the biological control based on competitive exclusion. In order to select potential biocontrol agents among isolates from the maize growing region in Argentina, a total of 512 A. flavus strains were isolated from maize kernels and soil samples. Thirty-six per cent of the isolates from maize kernels did not produce detectable levels of aflatoxins, while 73% of the isolates from soil were characterized as non-aflatoxin producers. Forty percent and 49% of the isolates from maize kernels and soil samples, respectively, were not producers of cyclopiazonic acid (CPA). Sclerotia morphology was evaluated using Czapek Dox media. Eighty-six per cent of the isolates from maize kernels and 85% of the isolates from soil samples were L sclerotia morphotype (average diameter > 400 μm). The remaining isolates did not produce sclerotia. All isolates had MAT 1-1 idiomorph. The competitive ability of 9 non aflatoxigenic strains, 4 CPA(+) and 5 CPA(-), was evaluated in co-inoculations of maize kernels with an aflatoxigenic strain. All evaluated strains significantly (p < 0.05) reduced aflatoxin contamination in maize kernels. The aflatoxin B 1 (AFB 1 ) reduction ranged from 6 to 60%. The strain A. flavus ARG5/30 isolated from maize kernels would be a good candidate as a potential biocontrol agent to be used in maize, since it was characterized as neither aflatoxin nor CPA producer, morphotype L, MAT 1-1 idiomorph, and reduced AFB 1 content in maize kernels by 59%. This study showed the competitive ability of potential aflatoxin biocontrol agents to be evaluated under field trials in a maize agro-ecosystem in Argentina. Copyright © 2018 Elsevier B.V. All rights reserved.

Short-chain fatty acids and poly-beta-hydroxyalkanoates: (New) Biocontrol agents for a sustainable animal production.

PubMed

Defoirdt, Tom; Boon, Nico; Sorgeloos, Patrick; Verstraete, Willy; Bossier, Peter

2009-01-01

Because of the risk of antibiotic resistance development, there is a growing awareness that antibiotics should be used more carefully in animal production. However, a decreased use of antibiotics could result in a higher frequency of pathogenic bacteria, which in its turn could lead to a higher incidence of infections. Short-chain fatty acids (SCFAs) have long been known to exhibit bacteriostatic activity. These compounds also specifically downregulate virulence factor expression and positively influence the gastrointestinal health of the host. As a consequence, there is currently considerable interest in SCFAs as biocontrol agents in animal production. Polyhydroxyalkanoates (PHAs) are polymers of beta-hydroxy short-chain fatty acids. Currently, PHAs are applied as replacements for synthetic polymers. These biopolymers can be depolymerised by many different microorganisms that produce extracellular PHA depolymerases. Interestingly, different studies provided some evidence that PHAs can also be degraded upon passage through the gastrointestinal tract of animals and consequently, adding these compounds to the feed might result in biocontrol effects similar to those described for SCFAs.

Investigating the compatibility of the biocontrol agent Clonostachys rosea IK726 with prodigiosin-producing Serratia rubidaea S55 and phenazine-producing Pseudomonas chlororaphis ToZa7.

PubMed

Kamou, Nathalie N; Dubey, Mukesh; Tzelepis, Georgios; Menexes, Georgios; Papadakis, Emmanouil N; Karlsson, Magnus; Lagopodi, Anastasia L; Jensen, Dan Funck

2016-05-01

This study was carried out to assess the compatibility of the biocontrol fungus Clonostachys rosea IK726 with the phenazine-producing Pseudomonas chlororaphis ToZa7 or with the prodigiosin-producing Serratia rubidaea S55 against Fusarium oxysporum f. sp. radicis-lycopersici. The pathogen was inhibited by both strains in vitro, whereas C. rosea displayed high tolerance to S. rubidaea but not to P. chlororaphis. We hypothesized that this could be attributed to the ATP-binding cassette (ABC) proteins. The results of the reverse transcription quantitative PCR showed an induction of seven genes (abcB1, abcB20, abcB26, abcC12, abcC12, abcG8 and abcG25) from subfamilies B, C and G. In planta experiments showed a significant reduction in foot and root rot on tomato plants inoculated with C. rosea and P. chlororaphis. This study demonstrates the potential for combining different biocontrol agents and suggests an involvement of ABC transporters in secondary metabolite tolerance in C. rosea.

Indigenous bacteria may interfere with the biocontrol of plant diseases

NASA Astrophysics Data System (ADS)

Someya, Nobutaka; Akutsu, Katsumi

2009-06-01

Prodigiosin is a reddish antibiotic pigment that plays an important role in the biocontrol of plant diseases by the bacterium Serratia marcescens. However, its activity is unstable under agricultural conditions; further, it can be degraded by various environmental factors. To examine the effect of epiphytic microbes on the stability of prodigiosin used for biological control processes, we collected a total of 1,280 bacterial isolates from the phylloplane of cyclamen and tomato plants. Approximately 72% of the bacterial strains isolated from the cyclamen plants and 66% of those isolated from the tomato plants grew on minimal agar medium containing 100 μg ml-1 prodigiosin. Certain isolates obtained from both plant species exhibited prodigiosin-degrading activity. We compared the 16S rRNA gene sequences derived from the isolates with sequences in a database. The comparison revealed that the sequences determined for the prodigiosin-degrading isolates were homologous to those of the genera Pseudomonas, Caulobacter, Rhizobium, Sphingomonas, Janthinobacterium, Novosphingobium, and Rathayibacter. These results indicate that indigenous epiphytic microorganisms may interfere with the interaction between plant pathogens and biocontrol agents by degrading the antibiotics produced by the agents.

Biocontrol of the toxigenic plant pathogen Fusarium culmorum by soil fauna in an agroecosystem.

PubMed

Meyer-Wolfarth, Friederike; Schrader, Stefan; Oldenburg, Elisabeth; Weinert, Joachim; Brunotte, Joachim

2017-08-01

In 2011 and 2013, a field experiment was conducted in a winter wheat field at Adenstedt (northern Germany) to investigate biocontrol and interaction effects of important members of the soil food web (Lumbricus terrestris, Annelida; Folsomia candida, Collembola and Aphelenchoides saprophilus, Nematoda) on the phytopathogenic fungus Fusarium culmorum in wheat straw. Therefore, soil fauna was introduced in mesocosms in defined numbers and combinations and exposed to either Fusarium-infected or non-infected wheat straw. L. terrestris was introduced in all faunal treatments and combined either with F. candida or A. saprophilus or both. Mesocosms filled with a Luvisol soil, a cover of different types of wheat straw and respective combinations of faunal species were established outdoors in the topsoil of a winter wheat field after harvest of the crop. After a time span of 4 and 8 weeks, the degree of wheat straw coverage of mesocosms was quantified to assess its attractiveness for the soil fauna. The content of Fusarium biomass in residual wheat straw and soil was determined using a double-antibody sandwich (DAS)-ELISA method. In both experimental years, the infected wheat straw was incorporated more efficiently into the soil than the non-infected control straw due to the presence of L. terrestris in all faunal treatments than the non-infected control straw. In addition, Fusarium biomass was reduced significantly in all treatments after 4 weeks (2011: 95-99%; 2013:15-54%), whereupon the decline of fungal biomass was higher in faunal treatments than in non-faunal treatments and differed significantly from them. In 2011, Fusarium biomass of the faunal treatments was below the quantification limit after 8 weeks. In 2013, a decline of Fusarium biomass was observed, but the highest content of Fusarium biomass was still found in the non-faunal treatments after 8 weeks. In the soil of all treatments, Fusarium biomass was below the quantification limit. The earthworm species L. terrestris revealed a considerable potential as an effective biocontrol agent contributing to a sustainable control of a Fusarium plant pathogen in wheat straw, thus reducing the infection risk for specific plant diseases in arable fields.

50-plus years of fungal viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghabrial, Said A., E-mail: saghab00@email.uky.edu; Castón, José R.; Jiang, Daohong

2015-05-15

Mycoviruses are widespread in all major taxa of fungi. They are transmitted intracellularly during cell division, sporogenesis, and/or cell-to-cell fusion (hyphal anastomosis), and thus their life cycles generally lack an extracellular phase. Their natural host ranges are limited to individuals within the same or closely related vegetative compatibility groups, although recent advances have established expanded experimental host ranges for some mycoviruses. Most known mycoviruses have dsRNA genomes packaged in isometric particles, but an increasing number of positive- or negative-strand ssRNA and ssDNA viruses have been isolated and characterized. Although many mycoviruses do not have marked effects on their hosts, thosemore » that reduce the virulence of their phytopathogenic fungal hosts are of considerable interest for development of novel biocontrol strategies. Mycoviruses that infect endophytic fungi and those that encode killer toxins are also of special interest. Structural analyses of mycoviruses have promoted better understanding of virus assembly, function, and evolution. - Highlights: • Historical perspective of fungal virus research. • Description, classification and diversity of fungal virus families. • Structural features of fungal virus particles. • Hypovirulence and exploitation of mycoviruses in biological control of plant pathogenic fungi.« less

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa.

PubMed

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa . Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg 2+ , Fe 2+ , and Zn 2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

PubMed Central

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy. PMID:29089939

Evaluation of the potential of Trichoderma viride in the control of fungal pathogens of Roselle (Hibiscus sabdariffa L.) in vitro.

PubMed

Eslaminejad Parizi, T; Ansaria, Mehdi; Elaminejad, Tahereh

2012-04-01

The potential of Trichoderma viride as a bio-control agent was evaluated in vitro against Roselle pathogens i.e. Phoma exigua, Fusarium nygamai and Rhizoctonia solani[1] using the dual culture technique. Volatile and non-volatile inhibitors of Trichoderma were also evaluated for this purpose. T. viride[2] was shown to have a marked inhibitory effect on the tested pathogens in vitro. Maximum inhibition occurred against P. exigua, with 71.76% reduction in mycelial radial growth. The three pathogens, P. exigua, F. nygamai and R. solani were also found to be susceptible to the volatile inhibitors produced by T. viride, giving rise to growth inhibition of about 68% in each case. When T. viride non-volatile metabolites were tested against the pathogens, maximum inhibition occurred against R. solani (73.95% mycelial growth inhibition), followed by P. exigua (37.17% inhibition). The inhibitory effect of the non-volatile metabolites on F. nygamai was, however, minimal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Endosymbiotic Bacteria Associated with the Mealy Bug, Rhizoecus amorphophalli (Hemiptera: Pseudococcidae)

PubMed Central

Sreerag, Ravikumar Sreekala; Jayaprakas, C. A.; Ragesh, L.; Kumar, Sasidharan Nishanth

2014-01-01

The mealy bug, Rhizoecus amorphophalli, is a menace to the aroid farmers due to the intensive infestation on stored tubers. Spraying of pesticides was able to control this pest but it always left a chance for fungal growth. Bacterial endosymbionts associated with the insects provide several benefits to their host. Since such endosymbionts play a vital role even in the physiology of their host, revealing the types of bacteria associated with mealy bug will give basic information, which may throw light on the management of this noxious pest. The present study is the first to identify bacterial endosymbionts associated with R. amorphophalli employing phenotypic characterization and 16S rDNA sequencing. Three culturable bacteria, namely, Bacillus subtilis, Staphylococcus gallinarum, and Staphylococcus saprophyticus, were isolated from R. amorphophalli. Moreover, the antibiotic susceptibility tests against the isolated bacteria showed that all the isolates were susceptible to the three antibiotics tested, except cephalexin. Recently, endosymbionts are used as effective biocontrol agents (BCAs) and the present study will stand as a connecting link in identification and effective utilization of these endosymbionts as BCAs for management of R. amorphophalli. PMID:27355014

Development of insect resistant maize plants expressing a chitinase gene from the cotton leaf worm, Spodoptera littoralis

PubMed Central

Osman, Gamal H.; Assem, Shireen K.; Alreedy, Rasha M.; El-Ghareeb, Doaa K.; Basry, Mahmoud A.; Rastogi, Anshu; Kalaji, Hazem M.

2015-01-01

Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents. Targeting chitin associated with the extracellular matrices or cell wall by insect chitinases may be an effective approach for controlling pest insects and pathogenic fungi. The ability of chitinases to attack and digest chitin in the peritrophic matrix or exoskeleton raises the possibility to use them as insect control method. In this study, an insect chitinase cDNA from cotton leaf worm (Spodoptera littoralis) has been synthesized. Transgenic maize plant system was used to improve its tolerance against insects. Insect chitinase transcripts and proteins were expressed in transgenic maize plants. The functional integrity and expression of chitinase in progenies of the transgenic plants were confirmed by insect bioassays. The bioassays using transgenic corn plants against corn borer (Sesamia cretica) revealed that ~50% of the insects reared on transgenic corn plants died, suggesting that transgenic maize plants have enhanced resistance against S. cretica. PMID:26658494

RNA-Seq reveals the molecular mechanism of trapping and killing of root-knot nematodes by nematode-trapping fungi.

PubMed

Pandit, Ramesh; Patel, Reena; Patel, Namrata; Bhatt, Vaibhav; Joshi, Chaitanya; Singh, Pawan Kumar; Kunjadia, Anju

2017-04-01

Nematode-trapping fungi are well known for their inherent potential to trap and kill nematodes using specialized trapping devices. However, the molecular mechanisms underlying the trapping and subsequent processes are still unclear. Therefore, in this study, we examined differential genes expression in two nematode-trapping fungi after baiting with nematode extracts. In Arthrobotrys conoides, 809 transcripts associated with diverse functions such as signal transduction, morphogenesis, stress response and peroxisomal proteins, proteases, chitinases and genes involved in the host-pathogen interaction showed differential expression with fold change (>±1.5 fold) in the presence of nematode extract with FDR (p-value < 0.001). G-proteins and mitogen activated protein kinases are considered crucial for signal transduction mechanism. Results of qRT-PCR of 20 genes further validated the sequencing data. Further, variations in gene expression among Duddingtonia flagrans and A. conoides showed septicity of nematode-trapping fungi for its host. The findings illustrate the molecular mechanism of fungal parasitism in A. conoides which may be helpful in developing a potential biocontrol agent against parasitic nematodes.

Unification of the macro- and microbiome in trophic ecology

USDA-ARS?s Scientific Manuscript database

Biological control is a key part of virtually any IPM program, and microbial bio-control agents represent particularly effective agents because of their capacity to be applied via conventional spray application methods. We are showing that fungi function just as arthropods do in the food web—the fun...

Genome sequence, assembly and characterization of two Metschnikowia fructicola strains used as biocontrol agents of postharvest diseases

USDA-ARS?s Scientific Manuscript database

The yeast Metschnikowia fructicola was reported as an efficient biological control agent of postharvest diseases of fruits and vegetables. Several mechanism of action by which M. fructicola inhibit postharvest pathogens were suggested including iron-binding compounds, induction of defense signaling...

Fusarium oxysporum f. sp. dianthi virus 1 accumulation is correlated with changes in virulence and other phenotypic traits of its fungal host.

PubMed

Lemus-Minor, Carlos German; Cañizares-Nolasco, Carmen; García-Pedrajas, Maria D D; Pérez-Artés, Encarnación

2018-03-08

Fusarium oxysporum f. sp. dianthi virus 1 (FodV1) was detected in isolate Fod 116 (Fod 116V + ) of Fusarium oxysporum f. sp. dianthi (Fod), reaching such a high accumulation level that it was clearly visible after agarose gel electrophoresis of total DNA extracts. FodV1 consists of four double-stranded RNA segments, that correspond to a new mycovirus in the Chrysoviridae family. We obtained an isolate of Fod 116 (Fod 116V - ) with only a residual level of FodV1 RNA accumulation by single-conidia selection. Compared to the Fod 116V - , isolate Fod 116V + showed significant phenotypic alterations in vegetative growth and virulence. The presence of a high titer of mycovirus FodV1 thus associated with a modified morphology and a reduced growth of the colonies on solid medium, and with a diminished conidiation in liquid medium. Inoculation of four susceptible carnation cultivars with either Fod 116V - or Fod 116V + showed that the presence of a high titer of FodV1 was also correlated with a significantly reduced virulence of its fungal host. All the results suggest that FodV1 could be associated with hypovirulence, identifying it as a potential biocontrol agent against Fusarium wilt of carnation. This is the first report of a mycovirus potentially associated to the induction of hypovirulence in the species Fusarium oxysporum.

Single-kernel analysis of fumonisins and other fungal metabolites in maize from South African subsistence farmers.

PubMed

Mogensen, J M; Sørensen, S M; Sulyok, M; van der Westhuizen, L; Shephard, G S; Frisvad, J C; Thrane, U; Krska, R; Nielsen, K F

2011-12-01

Fumonisins are important Fusarium mycotoxins mainly found in maize and derived products. This study analysed maize from five subsistence farmers in the former Transkei region of South Africa. Farmers had sorted kernels into good and mouldy quality. A total of 400 kernels from 10 batches were analysed; of these 100 were visually characterised as uninfected and 300 as infected. Of the 400 kernels, 15% were contaminated with 1.84-1428 mg kg(-1) fumonisins, and 4% (n=15) had a fumonisin content above 100 mg kg(-1). None of the visually uninfected maize had detectable amounts of fumonisins. The total fumonisin concentration was 0.28-1.1 mg kg(-1) for good-quality batches and 0.03-6.2 mg kg(-1) for mouldy-quality batches. The high fumonisin content in the batches was apparently caused by a small number (4%) of highly contaminated kernels, and removal of these reduced the average fumonisin content by 71%. Of the 400 kernels, 80 were screened for 186 microbial metabolites by liquid chromatography-tandem mass spectrometry, detecting 17 other fungal metabolites, including fusaric acid, equisetin, fusaproliferin, beauvericin, cyclosporins, agroclavine, chanoclavine, rugulosin and emodin. Fusaric acid in samples without fumonisins indicated the possibility of using non-toxinogenic Fusaria as biocontrol agents to reduce fumonisin exposure, as done for Aspergillus flavus. This is the first report of mycotoxin profiling in single naturally infected maize kernels. © 2011 Taylor & Francis

The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

PubMed

Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

2009-01-01

In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

Cloning and characterization of a novel chitinase gene (chi46) from Chaetomium globosum and identification of its biological activity.

PubMed

Liu, Z H; Yang, Q; Hu, S; Zhang, J D; Ma, J

2008-08-01

Chitinases play a major role in the defensive strategies of plants against fungal pathogens. In the current study, the gene for a 46-kDa endochitinase (chi46) was cloned from Chaetomium globosum, an important biocontrol fungus. The corresponding complementary deoxyribonucleic acid sequence was 1,350 bp in length, encoding 449 amino acid residues. The temporal expression of chi46, in response to the treatments of cell walls of six pathogens and confrontation against two fungal pathogens, was measured in C. globosum using real-time reverse transcription polymerase chain reaction. The expression of chi46 can be highly induced by exposure to the cell walls of plant pathogens and living pathogens, suggesting a role in plant disease resistance. The chi46 gene was inserted into the pPIC9 vector and transferred into the cells of Pichia pastoris GS115 for heterologous expression. The optimal reaction conditions for chitinase CHI46 activity were: 45 degrees C, pH of 5.0, and 5 mmol l(-1) of Cu2+. The maximum enzyme activity was 1.42 U ml(-1) following exposure to the cell wall chitin of Septoria tritici. The CHI46 enzyme can efficiently degrade cell walls of the phytopathogenic Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum, Valsa sordida, S. tritici, and Phytophthora sojae, demonstrating that it may be involved in the biocontrol mechanism of C. globosum.

PacC and pH–dependent transcriptome of the mycotrophic fungus Trichoderma virens

PubMed Central

2013-01-01

Background In fungi, environmental pH is an important signal for development, and successful host colonization depends on homeostasis. Surprisingly, little is known regarding the role of pH in fungal-fungal interactions. Species of Trichoderma grow as soil saprobes but many are primarily mycotrophic, using other fungi as hosts. Therefore, Trichoderma spp. are studied for their potential in biocontrol of plant diseases. Particularly in alkaline soil, pH is a critical limiting factor for these biofungicides, whose optimal growth pH is 4–6. Gaining an understanding of pH adaptability is an important step in broadening the activity spectrum of these economically important fungi. Results We studied the pH-responsive transcription factor PacC by gene knockout and by introduction of a constitutively active allele (pacCc). ΔpacC mutants exhibited reduced growth at alkaline pH, while pacCc strains grew poorly at acidic pH. In plate confrontation assays ΔpacC mutants showed decreased ability to compete with the plant pathogens Rhizoctonia solani and Sclerotium rolfsii. The pacCc strain exhibited an overgrowth of R. solani that was comparable to the wild type, but was unable to overgrow S. rolfsii. To identify genes whose expression is dependent on pH and pacC, we designed oligonucleotide microarrays from the transcript models of the T. virens genome, and compared the transcriptomes of wild type and mutant cultures exposed to high or low pH. Transcript levels from several functional classes were dependent on pacC, on pH, or on both. Furthermore, the expression of a set of pacC-dependent genes was increased in the constitutively-active pacCc strain, and was pH-independent in some, but not all cases. Conclusions PacC is important for biocontrol-related antagonism of other fungi by T. virens. As much as 5% of the transcriptome is pH-dependent, and of these genes, some 25% depend on pacC. Secondary metabolite biosynthesis and ion transport are among the relevant gene classes. We suggest that ΔpacC mutants may have lost their full biocontrol potential due to their inability to adapt to alkaline pH, to perceive ambient pH, or both. The results raise the novel possibility of genetically manipulating Trichoderma in order to improve adaptability and biocontrol at alkaline pH. PMID:23445374

Effects of sub-culturing on genetic and physiological parameters in different Beauveria bassiana isolates.

PubMed

Eivazian Kary, Naser; Alizadeh, Zhila

2017-05-01

Beauveria bassiana is a fungus which is widely used as a biological insecticide to control a number of economically important insect pests. Knowledge of the genetic diversity of the isolates, understanding the underlying nature of these evolutionary phenomena and finding appropriate and simple screening tools play an important role in developing effective biocontrol agents. Here, we monitored changes of electrophoretic karyotype of small molecules of extrachromosomal DNAs, presumably mitochondrial DNA or plasmids in several individual isolates of B. bassiana during the forced in vitro evolution by continual subculture on artificial media and then we evaluated these changes on the virulence of the isolates. Through agarose gel electrophoresis of the small extrachromosomal DNAs molecules, we found that mutations accumulate quickly and obvious changes take place in extrachromosomal DNAs of some isolates, although this did not always occur. This plasticity in response to culturing pressure suggests that buffering capacity of fungal genome against mutations is isolate dependent. Following the forced evolution by sub-culturing, five discriminable electrophoretic karyotype of extrachromosomal DNAs was observed among isolates. The results showed that some isolates are prone to deep mutations, but during enforced sub-culturing some others have efficiently conserved genome. These differences are influensive in screening appropriate isolates for mass production as a keystone in biocontrol program. To determine the effects of these changes on isolate traits, virulence, germination rate and spore-bound Pr1 activity were assessed parallel to sub-culturing. The results clearly revealed that parallel to sub-culturing and in correlation with karyotypic changes, isolates significantly suffered from virulence, germination rate and spore-bound Pr1 activity deficiencies. Copyright © 2017 Elsevier Inc. All rights reserved.

Aflatoxin contamination of groundnut and maize in Zambia: observed and potential concentrations.

PubMed

Kachapulula, P W; Akello, J; Bandyopadhyay, R; Cotty, P J

2017-06-01

The aims of the study were to quantify aflatoxins, the potent carcinogens associated with stunting and immune suppression, in maize and groundnut across Zambia's three agroecologies and to determine the vulnerability to aflatoxin increases after purchase. Aflatoxin concentrations were determined for 334 maize and groundnut samples from 27 districts using lateral-flow immunochromatography. Seventeen per cent of crops from markets contained aflatoxin concentrations above allowable levels in Zambia (10 μg kg -1 ). Proportions of crops unsafe for human consumption differed significantly (P < 0·001) among agroecologies with more contamination (38%) in the warmest (Agroecology I) and the least (8%) in cool, wet Agroecology III. Aflatoxin in groundnut (39 μg kg -1 ) and maize (16 μg kg -1 ) differed (P = 0·032). Poor storage (31°C, 100% RH, 1 week) increased aflatoxin in safe crops by over 1000-fold in both maize and groundnut. The L morphotype of Aspergillus flavus was negatively correlated with postharvest increases in groundnut. Aflatoxins are common in Zambia's food staples with proportions of unsafe crops dependent on agroecology. Fungal community structure influences contamination suggesting Zambia would benefit from biocontrol with atoxigenic A. flavus. Aflatoxin contamination across the three agroecologies of Zambia is detailed and the case for aflatoxin management with atoxigenic biocontrol agents provided. The first method for evaluating the potential for aflatoxin increase after purchase is presented. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of The Society for Applied Microbiology.

Comparative transcriptomics reveals different strategies of Trichoderma mycoparasitism

PubMed Central

2013-01-01

Background Trichoderma is a genus of mycotrophic filamentous fungi (teleomorph Hypocrea) which possess a bright variety of biotrophic and saprotrophic lifestyles. The ability to parasitize and/or kill other fungi (mycoparasitism) is used in plant protection against soil-borne fungal diseases (biological control, or biocontrol). To investigate mechanisms of mycoparasitism, we compared the transcriptional responses of cosmopolitan opportunistic species and powerful biocontrol agents Trichoderma atroviride and T. virens with tropical ecologically restricted species T. reesei during confrontations with a plant pathogenic fungus Rhizoctonia solani. Results The three Trichoderma spp. exhibited a strikingly different transcriptomic response already before physical contact with alien hyphae. T. atroviride expressed an array of genes involved in production of secondary metabolites, GH16 ß-glucanases, various proteases and small secreted cysteine rich proteins. T. virens, on the other hand, expressed mainly the genes for biosynthesis of gliotoxin, respective precursors and also glutathione, which is necessary for gliotoxin biosynthesis. In contrast, T. reesei increased the expression of genes encoding cellulases and hemicellulases, and of the genes involved in solute transport. The majority of differentially regulated genes were orthologues present in all three species or both in T. atroviride and T. virens, indicating that the regulation of expression of these genes is different in the three Trichoderma spp. The genes expressed in all three fungi exhibited a nonrandom genomic distribution, indicating a possibility for their regulation via chromatin modification. Conclusion This genome-wide expression study demonstrates that the initial Trichoderma mycotrophy has differentiated into several alternative ecological strategies ranging from parasitism to predation and saprotrophy. It provides first insights into the mechanisms of interactions between Trichoderma and other fungi that may be exploited for further development of biofungicides. PMID:23432824

Fungal endophytes of turmeric (Curcuma longa L.) and their biocontrol potential against pathogens Pythium aphanidermatum and Rhizoctonia solani.

PubMed

Vinayarani, G; Prakash, H S

2018-03-14

Endophytic fungi have been isolated from the healthy turmeric (Curcuma longa L.) rhizomes from South India. Thirty-one endophytes were identified based on morphological and ITS-rDNA sequence analysis. The isolated endophytes were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric respectively. Results revealed that only six endophytes showed > 70% suppression of test pathogens in antagonistic dual culture assays. The endophyte T. harzianum TharDOB-31 showed significant in vitro mycelial growth inhibition of P. aphanidermatum (76.0%) and R. solani (76.9%) when tested by dual culture method. The SEM studies of interaction zone showed morphological abnormalities like parasitism, shriveling, breakage and lysis of hyphae of the pathogens by endophyte TharDOB-31. Selected endophytic isolates recorded multiple plant growth promoting traits in in vitro studies. The rhizome bacterization followed by soil application of endophyte TharDOB-31 showed lowest Percent Disease Incidence of rhizome rot and leaf blight, 13.8 and 11.6% respectively. The treatment of TharDOB-31 exhibited significant increase in plant height (85 cm) and fresh rhizome yield/plant (425 g) in comparison with untreated control under greenhouse condition. The confocal microscopy validates the colonization of the TharDOB-31 in turmeric rhizomes. The secondary metabolites in ethyl acetate extract of TharDOB-31 were found to contain higher number of antifungal compounds by high resolution liquid chromatograph mass spectrometer analysis. Thereby, endophyte T. harzianum isolate can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

Evaluation of Rhodosporidium fluviale as biocontrol agent against Botrytis cinerea on apple fruit.

PubMed

Sansone, G; Lambrese, Y; Calvente, V; Fernández, G; Benuzzi, D; Sanz Ferramola, M

2018-05-01

The aim of the present work was to evaluate the ability of the native yeast Rhodosporidium fluviale to control Botrytis cinerea on apple fruit and to study the possible mechanisms of action with the goal of improving the control of gray mold. For this, the influence of application time of the yeast was studied simulating preventive and curative effects. Also, the effect of nonviable cells of the yeast in the biocontrol was assessed. According to the results obtained, the following mechanisms of action of R. fluviale could be proposed: 1- competition for space, 2- direct interaction between antagonist and pathogen, 3- induction of β-1,3-glucanase in apple tissue, 4- Probable production of glucanase in the apple wounds and 5- antifungal action of cellular components, probably chitin, present in the wall of yeast cells that could be the explanation for the activity of nonviable cells. Significance and Impact of the Study: Botrytis cinerea Pers: Fr, which causes gray mold of fruits and vegetables around the world, is difficult to control successfully because it is genetically variable and rapidly develops resistance to the chemicals commonly used for its control. This study is a contribution to the biocontrol of this phytopathogen fungus. The evaluation of the native yeast Rhodosporidium fluviale as biocontrol agent and the elucidation of possible mechanisms of action, including the participation of nonviable cells of this yeast, have not been reported up to date. © 2018 The Society for Applied Microbiology.

Morphology of the female reproductive system and physiological age-grading of Megamelus scutellaris (Hemiptera: Delphacidae), a biological control agent of water hyacinth

USDA-ARS?s Scientific Manuscript database

The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera:Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were ex...

Elucidation of biocontrol mechanisms of Trichoderma harzianum against different plant fungal pathogens: Universal yet host specific response.

PubMed

Sharma, Vivek; Salwan, Richa; Sharma, Prem N; Kanwar, S S

2017-02-01

In the present study, different transcripts of Trichoderma harzianum ThHP-3 were evaluated for their response against four fungal pathogens Fusarium oxysporum, Colletotrichum capsici, Colletotrichum truncatum and Gloesercospora sorghi using RT-qPCR. The time course study of T. harzianum transcripts related to signal transduction, lytic enzymes, secondary metabolites and various transporters revealed variation in expression against four fungal pathogens. In a broader term, the transcripts were upregulated at various time intervals but the optimum expression of cyp3, abc, nrp, tga1, pmk, ech42 and glh20 varied with respect to host fungi. Additionally, the expression of transcripts related to transporters/cytochromes was also observed against Fusarium oxysporum after 96h whereas transcripts related to secondary metabolites and lytic enzymes showed significant difference in expression against Colletotrichum spp. from 72 to 96h. This is first study on transcriptomic response of T. harzianum against pathogenic fungi which shows their host specific response. Copyright © 2016 Elsevier B.V. All rights reserved.

Isolation and characterization of rhizosphere bacteria for the biocontrol of the damping-off disease of tomatoes in Tunisia.

PubMed

Hammami, Inés; Ben Hsouna, Anis; Hamdi, Naceur; Gdoura, Radhouane; Triki, Mohamed Ali

2013-01-01

Fluorescent Pseudomonas spp., isolated from tomato and pepper plants rhizosphere soil, was evaluated in vitro as a potential antagonist of fungal pathogens. Pseudomonas strains were tested against the causal agents of tomatoes damping-off (Sclerotinia sclerotiorum), root rot (Fusarium solani), and causal agents of stem canker and leaf blight (Alternaria alternata). For this purpose, dual culture antagonism assays were carried out on 25% tryptic soy agar, King B medium and potato dextrose agar to determine the effect of the strains on mycelial growth of the pathogens. In addition, strains were screened for their ability to produce exoenzymes and siderophores. All the strains significantly inhibited Alternaria alternata, particularly in 25% TSA medium. Antagonistic effect on Sclerotinia sclerotiorum and Fusarium solani was greater on King B medium. Protease was produced by 30% of the strains, but no strain produced cellulase or chitinase. Finally, the selected Pseudomonas strain, Psf5, was evaluated on tomato seedling development and as a potential candidate for controlling tomato damping-off caused by Sclerotinia sclerotiorum, under growth chamber conditions. In vivo studies resulted in significant increases in plant stand as well as in root dry weight. Psf5 was able to establish and survive in tomato plants rhizosphere after 40days following the planting of bacterized seeds. © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Biotechnological Applications of Dimorphic Yeasts

NASA Astrophysics Data System (ADS)

Doiphode, N.; Joshi, C.; Ghormade, V.; Deshpande, M. V.

The dimorphic yeasts have the equilibrium between spherical growth (budding) and polarized (hyphal or pseudohyphal tip elongation) which can be triggered by change in the environmental conditions. The reversible growth phenomenon has made dimorphic yeasts as an useful model to understand fungal evolution and fungal differentiation, in general. In nature dimorphism is clearly evident in plant and animal fungal pathogens, which survive and most importantly proliferate in the respective hosts. However, number of organisms with no known pathogenic behaviour also show such a transition, which can be exploited for the technological applications due to their different biochemical make up under different morphologies. For instance, chitin and chitosan production using dimorphic Saccharomyces, Mucor, Rhizopus and Benjaminiella, oil degradation and biotransformation with yeast-form of Yarrowia species, bioremediation of organic pollutants, exopolysac-charide production by yeast-phase of Aureobasidium pullulans, to name a few. Myrothecium verrucaria can be used for seed dressing in its yeast form and it produces a mycolytic enzyme complex in its hyphal-form for the biocontrol of fungal pathogens, while Beauveria bassiana and other entomopathogens kill the insect pest by producing yeast- like cells in the insect body. The form-specific expression of protease, chitinase, lipase, ornithine decarboxylase, glutamate dehydrogenases, etc. make Benjaminiella poitrasii, Basidiobolus sp., and Mucor rouxii strains important in bioremediation, nanobiotechnology, fungal evolution and other areas.

The MAPKK FgMkk1 of Fusarium graminearum regulates vegetative differentiation, multiple stress response, and virulence via the cell wall integrity and high-osmolarity glycerol signaling pathways.

PubMed

Yun, Yingzi; Liu, Zunyong; Zhang, Jingze; Shim, Won-Bo; Chen, Yun; Ma, Zhonghua

2014-07-01

Mitogen-activated protein (MAP) kinases play crucial roles in regulating fungal development, growth and pathogenicity, and in responses to the environment. In this study, we characterized a MAP kinase kinase FgMkk1 in Fusarium graminearum, the causal agent of wheat head blight. Phenotypic analyses of the FgMKK1 mutant (ΔFgMKK1) showed that FgMkk1 is involved in the regulation of hyphal growth, pigmentation, conidiation, deoxynivalenol biosynthesis and virulence of F. graminearum. ΔFgMKK1 also showed increased sensitivity to cell wall-damaging agents, and to osmotic and oxidative stresses, but exhibited decreased sensitivity to the fungicides iprodione and fludioxonil. In addition, the mutant revealed increased sensitivity to a biocontrol agent, Trichoderma atroviride. Western blot assays revealed that FgMkk1 positively regulates phosphorylation of the MAP kinases Mgv1 and FgOs-2, the key component in the cell wall integrity (CWI) and high-osmolarity glycerol (HOG) signalling pathway respectively. Yeast two-hybrid assay indicated that Mgv1 interacts with a transcription factor FgRlm1. The FgRLM1 mutant (ΔFgRLM1) showed increased sensitivity to cell wall-damaging agents and exhibited decreased virulence. Taken together, our data indicated that FgMkk1 is an upstream component of Mgv1, and regulates vegetative differentiation, multiple stress response and virulence via the CWI and HOG signalling pathways. FgRlm1 may be a downstream component of Mgv1 in the CWI pathway in F. graminearum. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Biocontrol of Bacterial Fruit Blotch by Bacillus subtilis 9407 via Surfactin-Mediated Antibacterial Activity and Colonization

PubMed Central

Fan, Haiyan; Zhang, Zhanwei; Li, Yan; Zhang, Xun; Duan, Yongming; Wang, Qi

2017-01-01

In this study, Bacillus subtilis 9407 showed a strong antibacterial activity against Acidovorax citrulli in vitro and 61.7% biocontrol efficacy on melon seedlings 4 days post inoculation under greenhouse conditions. To understand the biocontrol mechanism of B. subtilis 9407, identify the primary antibacterial compound and determine its role in controlling bacterial fruit blotch (BFB), a srfAB deletion mutant (ΔsrfAB) was constructed. The ΔsrfAB which was deficient in production of surfactin, not only showed almost no ability to inhibit growth of A. citrulli but also decreased biofilm formation and reduced swarming motility. Colonization assay demonstrated that B. subtilis 9407 could conlonize on melon roots and leaves in a large population, while ΔsrfAB showed a four- to ten-fold reduction in colonization of melon roots and leaves. Furthermore, a biocontrol assay showed that ΔsrfAB lost the biocontrol efficacy. In summary, our results indicated that surfactin, which consists of C13- to C16-surfactin A was the primary antibacterial compound of B. subtilis 9407, and it played a major role in biofilm formation, swarming motility, colonization and suppressing BFB. We propose that the biocontrol activity of B. subtilis 9407 is the results of the coordinated action of surfactin-mediated antibacterial activity and colonization. This study reveals for the first time that the use of a B. subtilis strain as a potential biological control agent could efficiently control BFB by producing surfactin. PMID:29075242

Trichoderma Biocontrol: Signal Transduction Pathways Involved in Host Sensing and Mycoparasitism

PubMed Central

Zeilinger, Susanne; Omann, Markus

2007-01-01

Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes. In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP) kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride. PMID:19936091

Trichoderma biocontrol: signal transduction pathways involved in host sensing and mycoparasitism.

PubMed

Zeilinger, Susanne; Omann, Markus

2007-11-08

Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes. In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP) kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride.

Biocontrol of Bacterial Fruit Blotch by Bacillus subtilis 9407 via Surfactin-Mediated Antibacterial Activity and Colonization.

PubMed

Fan, Haiyan; Zhang, Zhanwei; Li, Yan; Zhang, Xun; Duan, Yongming; Wang, Qi

2017-01-01

In this study, Bacillus subtilis 9407 showed a strong antibacterial activity against Acidovorax citrulli in vitro and 61.7% biocontrol efficacy on melon seedlings 4 days post inoculation under greenhouse conditions. To understand the biocontrol mechanism of B. subtilis 9407, identify the primary antibacterial compound and determine its role in controlling bacterial fruit blotch (BFB), a srfAB deletion mutant (Δ srfAB ) was constructed. The Δ srfAB which was deficient in production of surfactin, not only showed almost no ability to inhibit growth of A. citrulli but also decreased biofilm formation and reduced swarming motility. Colonization assay demonstrated that B. subtilis 9407 could conlonize on melon roots and leaves in a large population, while Δ srfAB showed a four- to ten-fold reduction in colonization of melon roots and leaves. Furthermore, a biocontrol assay showed that Δ srfAB lost the biocontrol efficacy. In summary, our results indicated that surfactin, which consists of C13- to C16-surfactin A was the primary antibacterial compound of B. subtilis 9407, and it played a major role in biofilm formation, swarming motility, colonization and suppressing BFB. We propose that the biocontrol activity of B. subtilis 9407 is the results of the coordinated action of surfactin-mediated antibacterial activity and colonization. This study reveals for the first time that the use of a B. subtilis strain as a potential biological control agent could efficiently control BFB by producing surfactin.

Genome, Proteome and Structure of a T7-Like Bacteriophage of the Kiwifruit Canker Phytopathogen Pseudomonas syringae pv. actinidiae.

PubMed

Frampton, Rebekah A; Acedo, Elena Lopez; Young, Vivienne L; Chen, Danni; Tong, Brian; Taylor, Corinda; Easingwood, Richard A; Pitman, Andrew R; Kleffmann, Torsten; Bostina, Mihnea; Fineran, Peter C

2015-06-24

Pseudomonas syringae pv. actinidiae is an economically significant pathogen responsible for severe bacterial canker of kiwifruit (Actinidia sp.). Bacteriophages infecting this phytopathogen have potential as biocontrol agents as part of an integrated approach to the management of bacterial canker, and for use as molecular tools to study this bacterium. A variety of bacteriophages were previously isolated that infect P. syringae pv. actinidiae, and their basic properties were characterized to provide a framework for formulation of these phages as biocontrol agents. Here, we have examined in more detail φPsa17, a phage with the capacity to infect a broad range of P. syringae pv. actinidiae strains and the only member of the Podoviridae in this collection. Particle morphology was visualized using cryo-electron microscopy, the genome was sequenced, and its structural proteins were analysed using shotgun proteomics. These studies demonstrated that φPsa17 has a 40,525 bp genome, is a member of the T7likevirus genus and is closely related to the pseudomonad phages φPSA2 and gh-1. Eleven structural proteins (one scaffolding) were detected by proteomics and φPsa17 has a capsid of approximately 60 nm in diameter. No genes indicative of a lysogenic lifecycle were identified, suggesting the phage is obligately lytic. These features indicate that φPsa17 may be suitable for formulation as a biocontrol agent of P. syringae pv. actinidiae.

Releasing biocontrol agents: Risk assessment and overdue reform

Treesearch

Bob Peterson; Sharlene Sing

2007-01-01

Although the need for universally instituting formal risk assessment (RA) in the screening and approval process for non-native biological control (BC) agent releases has been widely acknowledged for the past several years, little seems to have been accomplished in terms of codifying this practice within a regulatory framework. Given the low success rate of classical BC...

Effects of biological control agents and exotic plant invasion on deer mouse populations

Treesearch

Yvette K. Ortega; Dean E. Pearson; Kevin S. McKelvey

2004-01-01

Exotic insects are commonly introduced as biological control agents to reduce densities of invasive exotic plants. Although current biocontrol programs for weeds take precautions to minimize ecological risks, little attention is paid to the potential nontarget effects of introduced food subsidies on native consumers. Previous research demonstrated that two gall flies (...

Ceratapion basicorne (Illiger) (Coleoptera: Curculionidae): laboratory and open field trials to assess its specificity as biocontrol agent of Centaurea solstitialis (Asteraceae: Cardueae)

USDA-ARS?s Scientific Manuscript database

Prospective biological control agents generally must be demonstrated to not pose risks to non-target plants. Laboratory experiments evaluating host plant specificity are the most common method of evaluating such risk; however, they are constrained by limitations of space and number of replicates, gi...

Whole genome sequencing of the Braconid parasitoid wasp Fopius arisanus, an important biocontrol agent of pest Tepritid fruit flies

USDA-ARS?s Scientific Manuscript database

The braconid wasp Fopius arisanus (Sonan) is an important biological control agent of tropical and subtropical pest fruit flies including two important global pests, the Mediterranean fruit fly (Ceratitis capitata), and the oriental fruit fly (Bactrocera dorsalis}). The goal of this study was to dev...

Interaction of media on production and biocontrol efficacy of Pseudomonas fluorescens and Bacillus subtilis against grey mould of apple.

PubMed

Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

2008-01-01

The medium has a profound effect on biocontrol agents, including ability to grow and effectiveness in disease control. In this study, growth and antagonistic efficacy of strains P-5 and P-35 (P. fluorescens), B-3 and B-16 (B. subtilis) were evaluated in combinations of two carbon (sucrose and molasses) and two nitrogen (urea and yeast extract) sources to optimize control of Botrytis cinerea on apple. All of the strains were grown in different liquid media (pH = 6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, molasses, malt extract and nutrient broth. Apples (Golden Delicious) were inoculated by a 25-microl suspension of 10(6) spores of B. cinerea per ml, wounding each fruit (in two sites separately). Then a 25-microl suspension of each strain, containing 2 x 10(8) cfu ml(-1) grown in each of the above culture media, was applied to each wound. Results indicated that Molasses + Yeast extract (1:1 w/w) medium supported rapid growth in all of the strains. The final growth of B. subtilis B-16 in Molasses + Yeast extract (1:1 w/w) medium was 5 x 10(9) cfu ml(-1). After ten days, all of the strains significantly inhibited pathogenicity of B. cinerea on apples. The biocontrol efficacy of B. subtilis B-3 in Molasses + Yeast extract (1:1 w/w) medium reduced the severity of grey mould from 100% (inoculated control) to less than 26.9%. After 20 days, Strain B-3 showed a considerable biocontrol efficacy in Molasses medium and reduced the severity of grey mould from 100% (inoculated control) to less than 38.2%. The results obtained in this study could be used to provide a reliable basis for the increase of population of biocontrol agents in fermentation process.

Evaluation of behaviour of Lachancea thermotolerans biocontrol agents on grape fermentations.

PubMed

Nally, M C; Ponsone, M L; Pesce, V M; Toro, M E; Vazquez, F; Chulze, S

2018-07-01

Previous researches have showed that Lachancea thermotolerans strains RCKT4 and RCKT5 inhibited the growth of Aspergillus. However, currently, there are no data on their nutritional preferences, as a possible substrate competitor against Saccharomyces cerevisiae, and their effects on fermentation. In this work, we observed that the biocontrol yeasts and S. cerevisiae BSc203, based on the utilization of 16 carbonate sources, revealed significant differences in the nutritional profile (biocontrol yeasts NS:0·25, BSc203 NS:0·56). Lachancea thermotolerans strains did not occupy the same niche as that of BSc203 (NOI:0·44). The biocontrol agents and BSc203 presented similar competitive attitude in terms of the sugar, ethanol and sulphite tolerances. During fermentation, the biocontrol yeasts were found to tolerate up to 12% v/v ethanol, 250 mg ml -1 of total SO 2 and 30° Brix sugar. In mixed cultures, L. thermotolerans strains did not negatively affect the growth of BSc203 and the wine quality, except when RCKT4 was initially inoculated at a high proportion in the mixed culture 1MSK4 (1%BSc203/99%RCKT4), resulting in a lower production of CO 2 and ethanol, in comparison with pure BSc203. RCKT5, at a high proportion, in 1MSK5 (1%BSc203/99%RCKT5) presented promising oenological properties. This fermentation showed lower acetic acid contents and higher total acidity than pure BSc203. Generally it is not evaluated if the biofungicide yeasts sprayed on vegetables alter the quality of the fermented products. This work focused on the importance of assessing the possible effects of yeast-based fungicides used in vineyards on grape fermentation, especially on Saccharomyces cerevisiae growth. In this context, the competition between biofungicide yeasts and S. cerevisiae under winemaking conditions is investigated. © 2018 The Society for Applied Microbiology.

Hydrogen Cyanide in the Rhizosphere: Not Suppressing Plant Pathogens, but Rather Regulating Availability of Phosphate

PubMed Central

Rijavec, Tomaž; Lapanje, Aleš

2016-01-01

Plant growth promoting rhizobacteria produce chemical compounds with different benefits for the plant. Among them, HCN is recognized as a biocontrol agent, based on its ascribed toxicity against plant pathogens. Based on several past studies questioning the validity of this hypothesis, we have re-addressed the issue by designing a new set of in vitro experiments, to test if HCN-producing rhizobacteria could inhibit the growth of phytopathogens. The level of HCN produced by the rhizobacteria in vitro does not correlate with the observed biocontrol effects, thus disproving the biocontrol hypothesis. We developed a new concept, in which HCN does not act as a biocontrol agent, but rather is involved in geochemical processes in the substrate (e.g., chelation of metals), indirectly increasing the availability of phosphate. Since this scenario can be important for the pioneer plants living in oligotrophic alpine environments, we inoculated HCN producing bacteria into sterile mineral sand together with germinating plants and showed that the growth of the pioneer plant French sorrel was increased on granite-based substrate. No such effect could be observed for maize, where plantlets depend on the nutrients stored in the endosperm. To support our concept, we used KCN and mineral sand and showed that mineral mobilization and phosphate release could be caused by cyanide in vitro. We propose that in oligotrophic alpine environments, and possibly elsewhere, the main contribution of HCN is in the sequestration of metals and the consequential indirect increase of nutrient availability, which is beneficial for the rhizobacteria and their plant hosts. PMID:27917154

De novo transcriptome analyses of host-fungal interactions in oil palm (Elaeis guineensis Jacq.).

PubMed

Ho, Chai-Ling; Tan, Yung-Chie; Yeoh, Keat-Ai; Ghazali, Ahmad-Kamal; Yee, Wai-Yan; Hoh, Chee-Choong

2016-01-19

Basal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively. Differential gene expression analyses revealed that jasmonate (JA) and salicylate (SA) may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots. In addition, G. boninense may compete with the host to control disease symptom through the transcriptional regulation of ethylene (ET) biosynthesis, reactive oxygen species (ROS) production and scavenging. The strengthening of host cell walls and production of pathogenesis-related proteins as well as antifungal secondary metabolites in host plants, are among the important defense mechanisms deployed by oil palm against G. boninense. Meanwhile, endophytic T. harzianum was shown to improve the of nutrition status and nutrient transportation in host plants. The findings of this analysis have enhanced our understanding on the molecular interactions of G. boninense and oil palm, and also the biocontrol mechanisms involving T. harzianum, thus contributing to future formulations of better strategies for prevention and treatment of BSR.

Implications of Bt traits on mycotoxin contamination in maize: Overview and recent experimental results in southern United States.

PubMed

Abbas, Hamed K; Zablotowicz, Robert M; Weaver, Mark A; Shier, W Thomas; Bruns, H Arnold; Bellaloui, Nacer; Accinelli, Cesare; Abel, Craig A

2013-12-04

Mycotoxin contamination levels in maize kernels are controlled by a complex set of factors including insect pressure, fungal inoculum potential, and environmental conditions that are difficult to predict. Methods are becoming available to control mycotoxin-producing fungi in preharvest crops, including Bt expression, biocontrol, and host plant resistance. Initial reports in the United States and other countries have associated Bt expression with reduced fumonisin, deoxynivalenol, and zearalenone contamination and, to a lesser extent, reduced aflatoxin contamination in harvested maize kernels. However, subsequent field results have been inconsistent, confirming that fumonisin contamination can be reduced by Bt expression, but the effect on aflatoxin is, at present, inconclusive. New maize hybrids have been introduced with increased spectra of insect control and higher levels of Bt expression that may provide important tools for mycotoxin reduction and increased yield due to reduced insect feeding, particularly if used together with biocontrol and host plant resistance.

An Evaluation of Antifungal Agents for the Treatment of Fungal Contamination in Indoor Air Environments

PubMed Central

Rogawansamy, Senthaamarai; Gaskin, Sharyn; Taylor, Michael; Pisaniello, Dino

2015-01-01

Fungal contamination in indoor environments has been associated with adverse health effects for the inhabitants. Remediation of fungal contamination requires removal of the fungi present and modifying the indoor environment to become less favourable to growth.  This may include treatment of indoor environments with an antifungal agent to prevent future growth. However there are limited published data or advice on chemical agents suitable for indoor fungal remediation. The aim of this study was to assess the relative efficacies of five commercially available cleaning agents with published or anecdotal use for indoor fungal remediation. The five agents included two common multi-purpose industrial disinfectants (Cavicide® and Virkon®), 70% ethanol, vinegar (4.0%−4.2% acetic acid), and a plant-derived compound (tea tree (Melaleuca alternifolia) oil) tested in both a liquid and vapour form. Tea tree oil has recently generated interest for its antimicrobial efficacy in clinical settings, but has not been widely employed for fungal remediation. Each antifungal agent was assessed for fungal growth inhibition using a disc diffusion method against a representative species from two common fungal genera, (Aspergillus fumigatus and Penicillium chrysogenum), which were isolated from air samples and are commonly found in indoor air. Tea tree oil demonstrated the greatest inhibitory effect on the growth of both fungi, applied in either a liquid or vapour form. Cavicide® and Virkon® demonstrated similar, although less, growth inhibition of both genera. Vinegar (4.0%–4.2% acetic acid) was found to only inhibit the growth of P. chrysogenum, while 70% ethanol was found to have no inhibitory effect on the growth of either fungi. There was a notable inhibition in sporulation, distinct from growth inhibition after exposure to tea tree oil, Virkon®, Cavicide® and vinegar. Results demonstrate that common cleaning and antifungal agents differ in their capacity to inhibit the growth of fungal genera found in the indoor air environment. The results indicate that tea tree oil was the most effective antifungal agent tested, and may have industrial application for the remediation of fungal contamination in residential and occupational buildings. PMID:26042369

An evaluation of antifungal agents for the treatment of fungal contamination in indoor air environments.

PubMed

Rogawansamy, Senthaamarai; Gaskin, Sharyn; Taylor, Michael; Pisaniello, Dino

2015-06-02

Fungal contamination in indoor environments has been associated with adverse health effects for the inhabitants. Remediation of fungal contamination requires removal of the fungi present and modifying the indoor environment to become less favourable to growth.  This may include treatment of indoor environments with an antifungal agent to prevent future growth. However there are limited published data or advice on chemical agents suitable for indoor fungal remediation. The aim of this study was to assess the relative efficacies of five commercially available cleaning agents with published or anecdotal use for indoor fungal remediation. The five agents included two common multi-purpose industrial disinfectants (Cavicide® and Virkon®), 70% ethanol, vinegar (4.0%-4.2% acetic acid), and a plant-derived compound (tea tree (Melaleuca alternifolia) oil) tested in both a liquid and vapour form. Tea tree oil has recently generated interest for its antimicrobial efficacy in clinical settings, but has not been widely employed for fungal remediation. Each antifungal agent was assessed for fungal growth inhibition using a disc diffusion method against a representative species from two common fungal genera, (Aspergillus fumigatus and Penicillium chrysogenum), which were isolated from air samples and are commonly found in indoor air. Tea tree oil demonstrated the greatest inhibitory effect on the growth of both fungi, applied in either a liquid or vapour form. Cavicide® and Virkon® demonstrated similar, although less, growth inhibition of both genera. Vinegar (4.0%-4.2% acetic acid) was found to only inhibit the growth of P. chrysogenum, while 70% ethanol was found to have no inhibitory effect on the growth of either fungi. There was a notable inhibition in sporulation, distinct from growth inhibition after exposure to tea tree oil, Virkon®, Cavicide® and vinegar. Results demonstrate that common cleaning and antifungal agents differ in their capacity to inhibit the growth of fungal genera found in the indoor air environment. The results indicate that tea tree oil was the most effective antifungal agent tested, and may have industrial application for the remediation of fungal contamination in residential and occupational buildings.

Efficacy of Bacillus subtilis and Bacillus amyloliquefaciens in the control of Aspergillus parasiticus growth and aflatoxins production on pistachio.

PubMed

Siahmoshteh, Fatemeh; Siciliano, Ilenia; Banani, Houda; Hamidi-Esfahani, Zohreh; Razzaghi-Abyaneh, Mehdi; Gullino, Maria Lodovica; Spadaro, Davide

2017-08-02

Pistachio (Pistacia vera) is an important nut for its economic, nutritional and health aspects but it can be contaminated by aflatoxigenic fungi in the field and during storage. Biological control could be considered as an alternative to chemical treatment. In this study, we evaluated the antifungal and anti-mycotoxigenic capability of two Bacillus spp. both in vitro and on pistachio kernels. In in vitro conditions, both strains were able to reduce the mycelial growth and they were able to degrade the four aflatoxins during the first three days after inoculation. AFG 1 and AFG 2 were rapidly degraded within two days of incubation with the bacterial strains. No aflatoxin was found in the bacterial cell walls, permitting exclusion of mycotoxin adsorption and hypothesis of an in vitro biodegradation as a mode of action. The cultivar of pistachio most susceptible to fungal colonization was 'Ahmad-Aghaei', selected among four main Iranian cultivars. A. parasiticus was able to grow and produce aflatoxins on pistachios, but at longer inoculation periods, a natural decrease of aflatoxins was registered. Both strains were able to reduce the fungal incidence and number of spores on pistachio with a stronger effect during the first 5dpi. The effect on aflatoxin content in vivo was less pronounced than in vitro, with a maximum effect at 8dpi. At longer times, there was a contrasting effect due to the lower activity of Bacillus spp. in stationary phase and higher growth of Aspergillus species. This consideration could explain the lack of aflatoxin reduction at 12dpi. Both bacterial strains showed good antifungal activity and aflatoxin reduction in in vitro conditions and on pistachio kernels. Altogether, these results indicate that Bacillus species could be considered as potential biocontrol agents to combat toxigenic fungal growth and subsequent aflatoxin contamination of nuts and agricultural crops in practice. Copyright © 2017. Published by Elsevier B.V.

Exogenous trehalose enhanced the biocontrol efficacy of Hanseniaspora uvarum against grape berry rots caused by Aspergillus tubingensis and Penicillium commune.

PubMed

Apaliya, Maurice Tibiru; Zhang, Hongyin; Zheng, Xiangfeng; Yang, Qiya; Mahunu, Gustav K; Kwaw, Emmanuel

2018-03-13

Primarily, chemical pesticides are commonly used to control preharvest and postharvest diseases of fruits and vegetables. However, there is strong public concern regarding the human and environmental health problems that might emanate from the residues of these chemical pesticides. As a result, biocontrol is often preferred due to its safety for humans and animals. The microbial antagonists employed often encounter variable climatic conditions, which affect their efficacy. In this study, the biocontrol efficacy of Hanseniaspora uvarum enhanced with trehalose against Aspergillus tubingensis and Penicillium commune in grapes was investigated. H. uvarum Y3 pretreated with 2.0% w/v trehalose in nutrient yeast dextrose broth (NYDB) before used significantly inhibited the incidence of decay and lesion diameter without affecting the sensory qualities of the grapes stored at either 4 °C or 20 °C. There was also a significant (P < 0.05) increase in the population dynamics of H. uvarum that was pretreated with 2% trehalose compared to that of H. uvarum alone. The in vitro assay on spore germination revealed an inhibition of A. tubingensis and P. commune by 85.6% and 87.0% respectively. Scanning electron microscopy results showed that both untreated H. uvarum and H. uvarum pre-treated with the 2% w/v trehalose before use inhibited fungal mycelium and development of grape rot. The biocontrol efficacy of H. uvarum was enhanced against grape rot caused by A. tubingensis and P. commune. The findings indicate the potential applicability of trehalose in the enhancement of H. uvarum. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Biocontrol efficacy of different isolates of Trichoderma against soil borne pathogen Rhizoctonia solani.

PubMed

Asad, Saeed Ahmad; Ali, Naeem; Hameed, Abdul; Khan, Sabaz Ali; Ahmad, Rafiq; Bilal, Muhammad; Shahzad, Muhammad; Tabassum, Ayesha

2014-01-01

In this study, the biocontrol abilities of water-soluble and volatile metabolites of three different isolates of Trichoderma (T. asperellum, T. harzianum and Trichoderma spp.) against soil borne plant pathogen Rhizoctonia solani were investigated both in vitro and in vivo. The results showed for the first time that mycelial growth inhibition of the pathogen was 74.4-67.8% with water-soluble metabolites as compared to 15.3-10.6% with volatile metabolites in vitro. In vivo antagonistic activity of Trichoderma isolates against R. solani was evaluated on bean plants under laboratory and greenhouse conditions. We observed that T. asperellum was more effective and consistent, lowering disease incidence up to 19.3% in laboratory and 30.5% in green house conditions. These results showed that three isolates of Trichoderma could be used as effective biocontrol agents against R. solani.

Southern Idaho student "bug crews": Weeds, youth, and biocontrol in the rangelands of Idaho

Treesearch

Sharlyn Gunderson-Izurieta; George P. Markin; Nan Reedy; Becky Frieberg

2009-01-01

Biological control of noxious weeds is an effective and widespread method often used by rangeland managers in the western United States. However, once biological control agents, usually insects, are released onto public and private lands there are few, if any, programs to follow up and monitor the effectiveness of these agents. A technique being used by some...

Wheat bran soil inoculant of sumateran nematode-trapping fungi as biocontrol agents of the root-knot nematode meloidogyne incognita on deli tobacco (nicotiana tabaccum l) cv. deli 4

NASA Astrophysics Data System (ADS)

Dwi Sri Hastuti, Liana; Faull, Jane

2018-03-01

A pot experiment was carried out to test the effectiveness of nematode-trapping fungi (NTF) isolated from Sumatera for controlling infection by the root-knot nematode (RKN) on Deli tobacco plant. Wheat bran soil containing 109 conidia of Arthrobotrys. oligospora, Candellabrella musiformis and Dactylella eudermata was added to the soil as a dry inoculum. Carbofuran was also applied as chemical agent and comparison treatment. Seedling tobacco (Nicotiana tabacum L.) cv. Deli 4 was inoculated with root knot (Meloidogyne incognita Chitwood.) seven days after the plant were transplanted to the pots. A. oligospora, C. musiformis and D. eudermata were found to be reliable as biocontrol agents, reducing the number of vermiform nematodes, swollen root, sausage shaped and galls in tobacco plant after 7, 15 and 30 days of infection with M. incognita. Treatment with NTF produced results that were comparable with Carbofuran® as a control agent in the reduction of the number of infections in tobacco plant caused by M. incognita in Nicotiana tabacum var. Deli 4. They also optimize the growth of the tobacco plants especially up to 15 days after infection.

Use of Endophytic and Rhizosphere Actinobacteria from Grapevine Plants To Reduce Nursery Fungal Graft Infections That Lead to Young Grapevine Decline

PubMed Central

Álvarez-Pérez, José Manuel; González-García, Sandra; Cobos, Rebeca; Olego, Miguel Ángel; Ibañez, Ana; Díez-Galán, Alba; Garzón-Jimeno, Enrique

2017-01-01

ABSTRACT Endophytic and rhizosphere actinobacteria isolated from the root system of 1-year-old grafted Vitis vinifera plants were evaluated for their activities against fungi that cause grapevine trunk diseases. A total of 58 endophytic and 94 rhizosphere isolates were tested. Based on an in vitro bioassay, 15.5% of the endophytic isolates and 30.8% of the rhizosphere isolates exhibited antifungal activity against the fungal pathogen Diplodia seriata, whereas 13.8% of the endophytic isolates and 16.0% of the rhizosphere isolates showed antifungal activity against Dactylonectria macrodidyma (formerly Ilyonectria macrodidyma). The strains which showed the greatest in vitro efficacy against both pathogens were further analyzed for their ability to inhibit the growth of Phaeomoniella chlamydospora and Phaeoacremonium minimum (formerly Phaeoacremonium aleophilum). Based on their antifungal activity, three rhizosphere isolates and three endophytic isolates were applied on grafts in an open-root field nursery in a 3-year trial. The field trial led to the identification of one endophytic strain, Streptomyces sp. VV/E1, and two rhizosphere isolates, Streptomyces sp. VV/R1 and Streptomyces sp. VV/R4, which significantly reduced the infection rates produced by the fungal pathogens Dactylonectria sp., Ilyonectria sp., P. chlamydospora, and P. minimum, all of which cause young grapevine decline. The VV/R1 and VV/R4 isolates also significantly reduced the mortality level of grafted plants in the nursery. This study shows that certain actinobacteria could represent a promising new tool for controlling fungal trunk pathogens that infect grapevine plants through the root system in nurseries. IMPORTANCE Grapevine trunk diseases are a major threat to the wine and grape industry worldwide. They cause a significant reduction in yields as well as in grape quality, and they can even cause plant death. Trunk diseases are caused by fungal pathogens that enter through pruning wounds and/or the root system. Although different strategies have recently been developed to protect pruning wounds using antifungal compounds (natural or synthetic) or biocontrol agents, no tools are yet available for controlling soil pathogens that infect plants through their root system. This study shows that different actinobacterial isolates, when applied to grafts in a nursery, can significantly reduce the infection rate caused by fungal pathogens that enter through the root system. This is a new, promising, and green alternative for preventing the decline of young grapevines in nurseries and vineyards. PMID:28986378

Use of Endophytic and Rhizosphere Actinobacteria from Grapevine Plants To Reduce Nursery Fungal Graft Infections That Lead to Young Grapevine Decline.

PubMed

Álvarez-Pérez, José Manuel; González-García, Sandra; Cobos, Rebeca; Olego, Miguel Ángel; Ibañez, Ana; Díez-Galán, Alba; Garzón-Jimeno, Enrique; Coque, Juan José R

2017-12-15

Endophytic and rhizosphere actinobacteria isolated from the root system of 1-year-old grafted Vitis vinifera plants were evaluated for their activities against fungi that cause grapevine trunk diseases. A total of 58 endophytic and 94 rhizosphere isolates were tested. Based on an in vitro bioassay, 15.5% of the endophytic isolates and 30.8% of the rhizosphere isolates exhibited antifungal activity against the fungal pathogen Diplodia seriata , whereas 13.8% of the endophytic isolates and 16.0% of the rhizosphere isolates showed antifungal activity against Dactylonectria macrodidyma (formerly Ilyonectria macrodidyma ). The strains which showed the greatest in vitro efficacy against both pathogens were further analyzed for their ability to inhibit the growth of Phaeomoniella chlamydospora and Phaeoacremonium minimum (formerly Phaeoacremonium aleophilum ). Based on their antifungal activity, three rhizosphere isolates and three endophytic isolates were applied on grafts in an open-root field nursery in a 3-year trial. The field trial led to the identification of one endophytic strain, Streptomyces sp. VV/E1, and two rhizosphere isolates, Streptomyces sp. VV/R1 and Streptomyces sp. VV/R4, which significantly reduced the infection rates produced by the fungal pathogens Dactylonectria sp., Ilyonectria sp., P. chlamydospora , and P. minimum , all of which cause young grapevine decline. The VV/R1 and VV/R4 isolates also significantly reduced the mortality level of grafted plants in the nursery. This study shows that certain actinobacteria could represent a promising new tool for controlling fungal trunk pathogens that infect grapevine plants through the root system in nurseries. IMPORTANCE Grapevine trunk diseases are a major threat to the wine and grape industry worldwide. They cause a significant reduction in yields as well as in grape quality, and they can even cause plant death. Trunk diseases are caused by fungal pathogens that enter through pruning wounds and/or the root system. Although different strategies have recently been developed to protect pruning wounds using antifungal compounds (natural or synthetic) or biocontrol agents, no tools are yet available for controlling soil pathogens that infect plants through their root system. This study shows that different actinobacterial isolates, when applied to grafts in a nursery, can significantly reduce the infection rate caused by fungal pathogens that enter through the root system. This is a new, promising, and green alternative for preventing the decline of young grapevines in nurseries and vineyards. Copyright © 2017 American Society for Microbiology.

Basic and applied research: Entomopathogenic nematodes

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema kill arthropods with the aid of their bacterial symbionts. These nematodes are potent microbial control agents that have been widely commercialized for control of economically important insect pests. Biocontrol efficacy relies...

Molecular Identification, Enzyme Assay, and Metabolic Profiling of Trichoderma spp.

PubMed

Bae, Soo-Jung; Park, Young-Hwan; Bae, Hyeun-Jong; Jeon, Junhyun; Bae, Hanhong

2017-06-28

The goal of this study was to identify and characterize selected Trichoderma isolates by metabolic profiling and enzyme assay for evaluation of their potential as biocontrol agents against plant pathogens. Trichoderma isolates were obtained from the Rural Development Administration Genebank Information Center (Wanju, Republic of Korea). Eleven Trichoderma isolates were re-identified using ribosomal DNA internal transcribed spacer (ITS) regions. ITS sequence results showed new identification of Trichoderma isolates. In addition, metabolic profiling of the ethyl acetate extracts of the liquid cultures of five Trichoderma isolates that showed the best anti- Phytophthora activities was conducted using gas chromatography-mass spectrometry. Metabolic profiling revealed that Trichoderma isolates shared common metabolites with well-known antifungal activities. Enzyme assays indicated strong cell walldegrading enzyme activities of Trichoderma isolates. Overall, our results indicated that the selected Trichoderma isolates have great potential for use as biocontrol agents against plant pathogens.

Sm2, a paralog of the Trichoderma cerato-platanin elicitor Sm1, is also highly important for plant protection conferred by the fungal-root interaction of Trichoderma with maize.

PubMed

Gaderer, Romana; Lamdan, Netta L; Frischmann, Alexa; Sulyok, Michael; Krska, Rudolf; Horwitz, Benjamin A; Seidl-Seiboth, Verena

2015-01-16

The proteins Sm1 and Sm2 from the biocontrol fungus Trichoderma virens belong to the cerato-platanin protein family. Members of this family are small, secreted proteins that are abundantly produced by filamentous fungi with all types of life-styles. Some species of the fungal genus Trichoderma are considered as biocontrol fungi because they are mycoparasites and are also able to directly interact with plants, thereby stimulating plant defense responses. It was previously shown that the cerato-platanin protein Sm1 from T. virens - and to a lesser extent its homologue Epl1 from Trichoderma atroviride - induce plant defense responses. The plant protection potential of other members of the cerato-platanin protein family in Trichoderma, however, has not yet been investigated. In order to analyze the function of the cerato-platanin protein Sm2, sm1 and sm2 knockout strains were generated and characterized. The effect of the lack of Sm1 and Sm2 in T. virens on inducing systemic resistance in maize seedlings, challenged with the plant pathogen Cochliobolus heterostrophus, was tested. These plant experiments were also performed with T. atroviride epl1 and epl2 knockout strains. In our plant-pathogen system T. virens was a more effective plant protectant than T. atroviride and the results with both Trichoderma species showed concordantly that the level of plant protection was more strongly reduced in plants treated with the sm2/epl2 knockout strains than with sm1/epl1 knockout strains. Although the cerato-platanin genes sm1/epl1 are more abundantly expressed than sm2/epl2 during fungal growth, Sm2/Epl2 are, interestingly, more important than Sm1/Epl1 for the promotion of plant protection conferred by Trichoderma in the maize-C. heterostrophus pathosystem.

Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae.

PubMed

Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M Q; Bruna, Roberto E; García-Véscovi, Eleonora; Osherov, Nir

2016-05-01

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae

PubMed Central

Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M. Q.; Bruna, Roberto E.; García-Véscovi, Eleonora

2016-01-01

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well. S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol. PMID:26896140

Ethanol production from chitosan by the nematophagous fungus Pochonia chlamydosporia and the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana.

PubMed

Aranda-Martinez, Almudena; Naranjo Ortiz, Miguel Ángel; Abihssira García, Isabel Sofía; Zavala-Gonzalez, Ernesto A; Lopez-Llorca, Luis Vicente

2017-11-01

Chitin is the second most abundant biopolymer after cellulose and virtually unexplored as raw material for bioethanol production. In this paper, we investigate chitosan, the deacetylated form of chitin which is the main component of shellfish waste, as substrate for bioethanol production by fungi. Fungal parasites of invertebrates such as the nematophagous Pochonia chlamydosporia (Pc) or the entomopathogens Beauveria bassiana (Bb) and Metarhizium anisopliae (Ma) are biocontrol agents of plant parasitic nematodes (eg. Meloidogyne spp.) or insect pests such as the red palm weevil (Rhynchophorus ferrugineus). These fungi degrade chitin-rich barriers for host penetration. We have therefore tested the chitin/chitosanolytic capabilities of Pc, Bb and Ma for generating reducing sugars using chitosan as only nutrient. Among the microorganisms used in this study, Pc is the best chitosan degrader, even under anaerobic conditions. These fungi have alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) encoding genes in their genomes. We have therefore analyzed their ethanol production under anaerobic conditions using chitosan as raw material. P. chlamydosporia is the largest ethanol producer from chitosan. Our studies are a starting point to develop chitin-chitosan based biofuels. Copyright © 2017 Elsevier GmbH. All rights reserved.

A novel fungal metabolite with beneficial properties for agricultural applications.

PubMed

Vinale, Francesco; Manganiello, Gelsomina; Nigro, Marco; Mazzei, Pierluigi; Piccolo, Alessandro; Pascale, Alberto; Ruocco, Michelina; Marra, Roberta; Lombardi, Nadia; Lanzuise, Stefania; Varlese, Rosaria; Cavallo, Pierpaolo; Lorito, Matteo; Woo, Sheridan L

2014-07-08

Trichoderma are ubiquitous soil fungi that include species widely used as biocontrol agents in agriculture. Many isolates are known to secrete several secondary metabolites with different biological activities towards plants and other microbes. Harzianic acid (HA) is a T. harzianum metabolite able to promote plant growth and strongly bind iron. In this work, we isolated from the culture filtrate of a T. harzianum strain a new metabolite, named isoharzianic acid (iso-HA), a stereoisomer of HA. The structure and absolute configuration of this compound has been determined by spectroscopic methods, including UV-Vis, MS, 1D and 2D NMR analyses. In vitro applications of iso-HA inhibited the mycelium radial growth of Sclerotinia sclerotiorum and Rhizoctonia solani. Moreover, iso HA improved the germination of tomato seeds and induced disease resistance. HPLC-DAD experiments showed that the production of HA and iso HA was affected by the presence of plant tissue in the liquid medium. In particular, tomato tissue elicited the production of HA but negatively modulated the biosynthesis of its analogue iso-HA, suggesting that different forms of the same Trichoderma secondary metabolite have specific roles in the molecular mechanism regulating the Trichoderma plant interaction.

Host specificity in biological control: insights from opportunistic pathogens

PubMed Central

Brodeur, Jacques

2012-01-01

Host/prey specificity is a significant concern in biological control. It influences the effectiveness of a natural enemy and the risks it might have on non-target organisms. Furthermore, narrow host specificity can be a limiting factor for the commercialization of natural enemies. Given the great diversity in taxonomy and mode of action of natural enemies, host specificity is a highly variable biological trait. This variability can be illustrated by opportunist fungi from the genus Lecanicillium, which have the capacity to exploit a wide range of hosts – from arthropod pests to fungi causing plant diseases – through different modes of action. Processes determining evolutionary trajectories in host specificity are closely linked to the modes of action of the natural enemy. This hypothesis is supported by advances in fungal genomics concerning the identity of genes and biological traits that are required for the evolution of life history strategies and host range. Despite the significance of specificity, we still need to develop a conceptual framework for better understanding of the relationship between specialization and successful biological control. The emergence of opportunistic pathogens and the development of ‘omic’ technologies offer new opportunities to investigate evolutionary principles and applications of the specificity of biocontrol agents. PMID:22949922

Antagonist effects of Bacillus spp. strains against Fusarium graminearum for protection of durum wheat (Triticum turgidum L. subsp. durum).

PubMed

Zalila-Kolsi, Imen; Ben Mahmoud, Afif; Ali, Hacina; Sellami, Sameh; Nasfi, Zina; Tounsi, Slim; Jamoussi, Kaïs

2016-11-01

Bacillus species are attractive due to their potential use in the biological control of fungal diseases. Bacillus amyloliquefaciens strain BLB369, Bacillus subtilis strain BLB277, and Paenibacillus polymyxa strain BLB267 were isolated and identified using biochemical and molecular (16S rDNA, gyrA, and rpoB) approaches. They could produce, respectively, (iturin and surfactin), (surfactin and fengycin), and (fusaricidin and polymyxin) exhibiting broad spectrum against several phytopathogenic fungi. In vivo examination of wheat seed germination, plant height, phenolic compounds, chlorophyll, and carotenoid contents proved the efficiency of the bacterial cells and the secreted antagonist activities to protect Tunisian durum wheat (Triticum turgidum L. subsp. durum) cultivar Om Rabiia against F. graminearum fungus. Application of single bacterial culture medium, particularly that of B. amyloliquefaciens, showed better protection than combinations of various culture media. The tertiary combination of B. amyloliquefaciens, B. subtilis, and P. polymyxa bacterial cells led to the highest protection rate which could be due to strains synergistic or complementary effects. Hence, combination of compatible biocontrol agents could be a strategic approach to control plant diseases. Copyright © 2016 Elsevier GmbH. All rights reserved.

Antimicrobial Activity of Medicinal Plants Correlates with the Proportion of Antagonistic Endophytes

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan; Behrendt, Undine; Ahmad, Parvaiz; Berg, Gabriele

2017-01-01

Medicinal plants are known to harbor potential endophytic microbes, due to their bioactive compounds. In a first study of ongoing research, endophytic bacteria were isolated from two medicinal plants, Hypericum perforatum and Ziziphora capitata with contrasting antimicrobial activities from the Chatkal Biosphere Reserve of Uzbekistan, and their plant-specific traits involved in biocontrol and plant growth promotion were evaluated. Plant extracts of H. perforatum exhibited a remarkable activity against bacterial and fungal pathogens, whereas extracts of Z. capitata did not exhibit any potential antimicrobial activity. Matrix-assisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) was used to identify plant associated culturable endophytic bacteria. The isolated culturable endophytes associated with H. perforatum belong to eight genera (Arthrobacter, Achromobacter, Bacillus, Enterobacter, Erwinia, Pseudomonas, Pantoea, Serratia, and Stenotrophomonas). The endophytic isolates from Z. capitata also contain those genera except Arthrobacter, Serratia, and Stenotrophomonas. H. perforatum with antibacterial activity supported more bacteria with antagonistic activity, as compared to Z. capitata. The antagonistic isolates were able to control tomato root rot caused by Fusarium oxysporum and stimulated plant growth under greenhouse conditions and could thus be a cost-effective source for agro-based biological control agents. PMID:28232827

Potent Nematicidal Activity and New Hybrid Metabolite Production by Disruption of a Cytochrome P450 Gene Involved in the Biosynthesis of Morphological Regulatory Arthrosporols in Nematode-Trapping Fungus Arthrobotrys oligospora.

PubMed

Song, Tian-Yang; Xu, Zi-Fei; Chen, Yong-Hong; Ding, Qiu-Yan; Sun, Yu-Rong; Miao, Yang; Zhang, Ke-Qin; Niu, Xue-Mei

2017-05-24

Types of polyketide synthase-terpenoid synthase (PKS-TPS) hybrid metabolites, including arthrosporols with significant morphological regulatory activity, have been elucidated from nematode-trapping fungus Arthrobotrys oligospora. A previous study suggested that the gene cluster AOL_s00215 in A. oligospora was involved in the production of arthrosporols. Here, we report that disruption of one cytochrome P450 monooxygenase gene AOL_s00215g280 in the cluster resulted in significant phenotypic difference and much aerial hyphae. A further bioassay indicated that the mutant showed a dramatic decrease in the conidial formation but developed numerous traps and killed 85% nematodes within 6 h in contact with prey, in sharp contrast to the wild-type strain with no obvious response. Chemical investigation revealed huge accumulation of three new PKS-TPS epoxycyclohexone derivatives with different oxygenated patterns around the epoxycyclohexone moiety and the absence of arthrosporols in the cultural broth of the mutant ΔAOL_s00215g280. These findings suggested that a study on the biosynthetic pathway for morphological regulatory metabolites in nematode-trapping fungus would provide an efficient way to develop new fungal biocontrol agents.

Oxidative damage induced by heat stress could be relieved by nitric oxide in Trichoderma harzianum LTR-2.

PubMed

Yu, Yang; Yang, Zijun; Guo, Kai; Li, Zhe; Zhou, Hongzi; Wei, Yanli; Li, Jishun; Zhang, Xinjian; Harvey, Paul; Yang, Hetong

2015-04-01

Trichoderma harzianum is an important commercial biocontrol fungal agent. The temperature has been shown to be an important parameter and strain-specific to the mycelia growth of fungi, but less report makes the known of the mechanisms in T. harzianum. In our study, a 6-h treatment of heat increased the thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) concentration in mycelia to 212 and 230 % the level of the control, respectively. The exogenous NO donor sodium nitroprusside (150 μM) reduced the TBARS concentration to 53 % of that under heat stress (HS). At the same time, the NO-specific scavenger at 250 μM, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-1-oxyl-3-oxide, prevented the exogenous NO-relieved TBARS accumulation under HS. The increased NO concentration under HS was reduced 41 % by the NO synthase (NOS) inhibitor L-N(G)-nitroarginine methyl ester, but not the nitrate reductase (NR) inhibitor tungstate. Our study exhibited that NO can protect the mycelia of T. harzianum from HS and reduce the oxidative damage by enhancing the activity of NOS and NR.

A Novel Bacteriophage Targeting Cronobacter sakazakii Is a Potential Biocontrol Agent in Foods

PubMed Central

Lee, Ju-Hoon; Bai, Jaewoo; Shin, Hakdong; Kim, Yeran; Park, Bookyung; Heu, Sunggi

2015-01-01

Cronobacter sakazakii is an important pathogen that causes high mortality in infants. Due to its occasional antibiotic resistance, a bacteriophage approach might be an alternative effective method for the control of this pathogen. To develop a novel biocontrol agent using bacteriophages, the C. sakazakii-infecting phage CR5 was newly isolated and characterized. Interestingly, this phage exhibited efficient and relatively durable host lysis activity. In addition, a specific gene knockout study and subsequent complementation experiment revealed that this phage infected the host strain using the bacterial flagella. The complete genome sequence analysis of phage CR5 showed that its genome contains 223,989 bp of DNA, including 231 predicted open reading frames (ORFs), and it has a G+C content of 50.06%. The annotated ORFs were classified into six functional groups (structure, packaging, host lysis, DNA manipulation, transcription, and additional functions); no gene was found to be related to virulence or toxin or lysogen formation, but >80% of the predicted ORFs are unknown. In addition, a phage proteomic analysis using SDS-PAGE and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) revealed that seven phage structural proteins are indeed present, supporting the ORF predictions. To verify the potential of this phage as a biocontrol agent against C. sakazakii, it was added to infant formula milk contaminated with a C. sakazakii clinical isolate or food isolate, revealing complete growth inhibition of the isolates by the addition of phage CR5 when the multiplicity of infection (MOI) was 105. PMID:26497465

Microbiological control of soil-borne phytopathogenic fungi with special emphasis on wilt-inducing Fusarium oxysporum.

PubMed

Alabouvette, Claude; Olivain, Chantal; Migheli, Quirico; Steinberg, Christian

2009-11-01

Plant diseases induced by soil-borne plant pathogens are among the most difficult to control. In the absence of effective chemical control methods, there is renewed interest in biological control based on application of populations of antagonistic micro-organisms. In addition to Pseudomonas spp. and Trichoderma spp., which are the two most widely studied groups of biological control agents, the protective strains of Fusarium oxysporum represent an original model. These protective strains of F. oxysporum can be used to control wilt induced by pathogenic strains of the same species. Exploring the mechanisms involved in the protective capability of these strains is not only necessary for their development as commercial biocontrol agents but raises many basic questions related to the determinism of pathogenicity versus biocontrol capacity in the F. oxysporum species complex. In this paper, current knowledge regarding the interaction between the plant and the protective strains is reviewed in comparison with interactions between the plant and pathogenic strains. The success of biological control depends not only on plant-microbial interactions but also on the ecological fitness of the biological control agents.

Biological Control beneath the Feet: A Review of Crop Protection against Insect Root Herbivores.

PubMed

Kergunteuil, Alan; Bakhtiari, Moe; Formenti, Ludovico; Xiao, Zhenggao; Defossez, Emmanuel; Rasmann, Sergio

2016-11-29

Sustainable agriculture is certainly one of the most important challenges at present, considering both human population demography and evidence showing that crop productivity based on chemical control is plateauing. While the environmental and health threats of conventional agriculture are increasing, ecological research is offering promising solutions for crop protection against herbivore pests. While most research has focused on aboveground systems, several major crop pests are uniquely feeding on roots. We here aim at documenting the current and potential use of several biological control agents, including micro-organisms (viruses, bacteria, fungi, and nematodes) and invertebrates included among the macrofauna of soils (arthropods and annelids) that are used against root herbivores. In addition, we discuss the synergistic action of different bio-control agents when co-inoculated in soil and how the induction and priming of plant chemical defense could be synergized with the use of the bio-control agents described above to optimize root pest control. Finally, we highlight the gaps in the research for optimizing a more sustainable management of root pests.

Biological Control beneath the Feet: A Review of Crop Protection against Insect Root Herbivores

PubMed Central

Kergunteuil, Alan; Bakhtiari, Moe; Formenti, Ludovico; Xiao, Zhenggao; Defossez, Emmanuel; Rasmann, Sergio

2016-01-01

Sustainable agriculture is certainly one of the most important challenges at present, considering both human population demography and evidence showing that crop productivity based on chemical control is plateauing. While the environmental and health threats of conventional agriculture are increasing, ecological research is offering promising solutions for crop protection against herbivore pests. While most research has focused on aboveground systems, several major crop pests are uniquely feeding on roots. We here aim at documenting the current and potential use of several biological control agents, including micro-organisms (viruses, bacteria, fungi, and nematodes) and invertebrates included among the macrofauna of soils (arthropods and annelids) that are used against root herbivores. In addition, we discuss the synergistic action of different bio-control agents when co-inoculated in soil and how the induction and priming of plant chemical defense could be synergized with the use of the bio-control agents described above to optimize root pest control. Finally, we highlight the gaps in the research for optimizing a more sustainable management of root pests. PMID:27916820

Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

PubMed Central

Kamber, Tim; Lansdell, Theresa A.; Stockwell, Virginia O.; Ishimaru, Carol A.; Smits, Theo H. M.

2012-01-01

Pantoea vagans C9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth of Erwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates of P. vagans C9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known as Nß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster in P. vagans C9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters in Pantoea agglomerans CU0119 and Serratia proteamaculans 568. A low incidence of detection of the biosynthetic cluster in a collection of 45 Pantoea spp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains. PMID:22504810

Unraveling the efficient applications of secondary metabolites of various Trichoderma spp.

PubMed

Keswani, Chetan; Mishra, Sandhya; Sarma, Birinchi Kumar; Singh, Surya Pratap; Singh, Harikesh Bahadur

2014-01-01

Recent shift in trends of agricultural practices from application of synthetic fertilizers and pesticides to organic farming has brought into focus the use of microorganisms that carryout analogous function. Trichoderma spp. is one of the most popular genera of fungi commercially available as a plant growth promoting fungus (PGPF) and biological control agent. Exploitation of the diverse nature of secondary metabolites produced by different species of Trichoderma augments their extensive utility in agriculture and related industries. As a result, Trichoderma has achieved significant success as a powerful biocontrol agent at global level. The endorsement of Trichoderma spp. by scientific community is based on the understanding of its mechanisms of action against a large set of fungal, bacterial and in certain cases viral infections. However, it is still an agnostic view that there could be any single major mode of operation, although it is argued that all mechanisms operate simultaneously in a synchronized fashion. The central idea behind this review article is to emphasize the potentiality of applications of target specific secondary metabolites of Trichoderma for controlling phytopathogens as a substitute of commercially available whole organism formulations. With the aim to this point, we have compiled an inclusive list of secondary metabolites produced by different species of Trichoderma and their applications in diverse areas with the major emphasis on agriculture. Outlining the importance and diverse activities of secondary metabolites of Trichoderma besides its relevance to agriculture would generate greater understanding of their other important and beneficial applications apart from target specific biopesticides.

Transcriptome analysis of Brassica juncea var. tumida Tsen responses to Plasmodiophora brassicae primed by the biocontrol strain Zhihengliuella aestuarii.

PubMed

Luo, Yuanli; Dong, Daiwen; Su, Yu; Wang, Xuyi; Peng, Yumei; Peng, Jiang; Zhou, Changyong

2018-05-01

Mustard clubroot, caused by Plasmodiophora brassicae, is a serious disease that affects Brassica juncea var. tumida Tsen, a mustard plant that is the raw material for a traditional fermented food manufactured in Chongqing, China. In our laboratory, we screened the antagonistic bacteria Zhihengliuella aestuarii against P. brassicae. To better understand the biocontrol mechanism, three transcriptome analyses of B. juncea var. tumida Tsen were conducted using Illumina HiSeq 4000, one from B. juncea only inoculated with P. brassicae (P), one inoculated with P. brassica and the biocontrol agent Z. aestuarii at the same time (P + B), and the other was the control (H), in which P. brassicae was replaced by sterile water. A total of 19.94 Gb was generated by Illumina HiSeq sequencing. The sequence data were de novo assembled, and 107,617 unigenes were obtained. In total, 5629 differentially expressed genes between biocontrol-treated (P + B) and infected (P) samples were assigned to 126 KEGG pathways. Using multiple testing corrections, 20 pathways were significantly enriched with Qvalue ≤ 0.05. The resistance-related genes, involved in the production of pathogenesis-related proteins, pathogen-associated molecular pattern-triggered immunity, and effector-triggered immunity signaling pathways, calcium influx, salicylic acid pathway, reactive oxygen intermediates, and mitogen-activated protein kinase cascades, and cell wall modification, were obtained. The various defense responses induced by the biocontrol strain combatted the P. brassicae infection. The genes and pathways involved in plant resistance were induced by a biocontrol strain. The transcriptome data explained the molecular mechanism of the potential biocontrol strain against P. brassicae. The data will also serve as an important public information platform to study B. juncea var. tumida Tsen and will be useful for breeding mustard plants resistant to P. brassicae.

Biocontrol potential of Trichoderma harzianum isolate T-aloe against Sclerotinia sclerotiorum in soybean.

PubMed

Zhang, Fuli; Ge, Honglian; Zhang, Fan; Guo, Ning; Wang, Yucheng; Chen, Long; Ji, Xiue; Li, Chengwei

2016-03-01

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2(-)) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Pasteuria endospore attachment to Pratylenchus species

USDA-ARS?s Scientific Manuscript database

Pasteuria spp. are endospore-forming bacteria, and most of them are obligate parasites of nematodes. A number of studies have demonstrated that Pasteuria can effectively suppress nematode populations in natural fields and have promising potential as biocontrol agents. However, parasitism of nematode...

Identification of differentially expressed genes associated with changes in the morphology of Pichia fermentans on apple and peach fruit.

PubMed

Fiori, Stefano; Scherm, Barbara; Liu, Jia; Farrell, Robert; Mannazzu, Ilaria; Budroni, Marilena; Maserti, Bianca E; Wisniewski, Michael E; Migheli, Quirico

2012-11-01

Pichia fermentans (strain DISAABA 726) is an effective biocontrol agent against Monilinia fructicola and Botrytis cinerea when inoculated in artificially wounded apple fruit but is an aggressive pathogen when inoculated on wounded peach fruit, causing severe fruit decay. Pichia fermentans grows as budding yeast on apple tissue and exhibits pseudohyphal growth on peach tissue, suggesting that dimorphism may be associated with pathogenicity. Two complementary suppressive subtractive hybridization (SSH) strategies, that is, rapid subtraction hybridization (RaSH) and PCR-based subtraction, were performed to identify genes differentially expressed by P. fermentans after 24-h growth on apple vs. peach fruit. Gene products that were more highly expressed on peach than on apple tissue, or vice versa, were sequenced and compared with available yeast genome sequence databases. Several of the genes more highly expressed, when P. fermentans was grown on peach, were related to stress response, glycolysis, amino acid metabolism, and alcoholic fermentation but surprisingly not to cell wall degrading enzymes such as pectinases or cellulases. The dual activity of P. fermentans as both a biocontrol agent and a pathogen emphasizes the need for a thorough risk analysis of potential antagonists to avoid unpredictable results that could negatively impact the safe use of postharvest biocontrol strategies. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

PubMed

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent

PubMed Central

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China’s Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent. PMID:27832162

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non-target species.

PubMed

McColl, K A; Sunarto, A; Slater, J; Bell, K; Asmus, M; Fulton, W; Hall, K; Brown, P; Gilligan, D; Hoad, J; Williams, L M; Crane, M St J

2017-09-01

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV-3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV-3 of a range of non-target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100-1000 times the approximate minimum amount of CyHV-3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post-challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV-3, and, in particular, all RT-PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV-3 as a potential biocontrol agent that is specific for carp. © 2016 John Wiley & Sons Ltd.

Potential for using Verticillium albo-atrum as a biocontrol agent for tree-of-heaven (Ailanthus altissima)

Treesearch

Donald D. Davis; Matthew Kasson; Mark Schall

2011-01-01

Extensive, unprecedented wilt and mortality of the highly invasive, exotic tree-of-heaven (Ailanthus altissima) occurred recently within mixed hardwood forests in south-central Pennsylvania. Until this study, the cause of the epidemic was unknown.

Responses of yeast biocontrol agents to environmental stress

USDA-ARS?s Scientific Manuscript database

Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeasts, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management...

[Fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato].

PubMed

Meng, Pin-Pin; Liu, Xing; Qiu, Hui-Zhen; Zhang, Wen-Ming; Zhang, Chun-Hong; Wang, Di; Zhang, Jun-Lian; Shen, Qi-Rong

2012-11-01

Continuous cropping obstacle is one of the main restriction factors in potato industry. In order to explore the mechanisms of potato's continuous cropping obstacle and to reduce the impact on potato's tuber yield, a field experiment combined with PCR-DGGE molecular fingerprinting was conducted to investigate the fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato. With the increasing year of potato' s continuous cropping, the numbers of visible bands in rhizosphere fungal DGGE profiles increased obviously. As compared with that of CK (rotation cropping), the operational taxonomic unit (OTU) in treatments of one to five years continuous cropping was increased by 38.5%, 38.5%, 30.8%, 46.2%, and 76.9% respectively, indicating that potato's continuous cropping caused an obvious increase in the individual numbers of dominant fungal populations in rhizosphere soil. Also with the increasing year of potato's continuous cropping, the similarity of the fungal population structure among the treatments had a gradual decrease. The sequencing of the fungal DGGE bands showed that with the increasing year of continuous cropping, the numbers of the potato's rhizosphere soil-borne pathogens Fusarium oxysporum and F. solani increased obviously, while the number of Chaetomium globosum, as a biocontrol species, had a marked decrease in the fifth year of continuous cropping. It was suggested that potato' s continuous cropping caused the pathogen fungal populations become the dominant microbial populations in rhizosphere soil, and the rhizosphere micro-ecological environment deteriorated, which in turn affected the root system, making the root vigor and its absorption area reduced, and ultimately, the tuber yield decreased markedly.

Change of growth promotion and disease resistant of wheat seedling by application of biocontrol bacterium Pseudochrobactrum kiredjianiae A4 under simulated microgravity

NASA Astrophysics Data System (ADS)

Fu, Yuming; Gao, Han; Li, Hongyan; Qin, Youcai; Tang, Wen; Lu, Jinying; Li, Ming; Shao, Lingzhi; Liu, Hong

2017-10-01

Plant disease control and prevention in microgravity are critical for space plant cultivation. This study investigated the effects of a biocontrol bacterium Pseudochrobactrum kiredjianiae A4 on growth development and antifungal potential of wheat seedlings under simulated microgravity. The growth, antioxidant status and plant immune hormone of both non-infected and infected wheat seedlings were detected before and after inoculation of A4 strains under simulated microgravity condition (μG) and ground condition (1G). Our results showed that bacteria A4 promoted wheat growth by increasing root length and biomass accumulation and meanwhile enhancing fungal disease resistance through improving the antioxidant enzyme activities and plant hormone secretion. Moreover, A4 exhibited a weaker promotion ability on wheat biomass accumulation and disease resistance under μG condition compared to that under 1G. These results not only expand our understanding of the impact of microgravity on plant-microbe interaction, but also provide valuable insights into using plant beneficial microbes for plant cultivation and crop protection in space.

Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens.

PubMed

Cordero-Bueso, Gustavo; Mangieri, Nicola; Maghradze, David; Foschino, Roberto; Valdetara, Federica; Cantoral, Jesús M; Vigentini, Ileana

2017-01-01

The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinerea, Aspergillus carbonarius , and Penicillium expansum pathogen species. In particular, yeast isolation was carried out from grape berries of Vitis vinifera ssp sylvestris populations, of the Eurasian area, and V. vinifera ssp vinifera cultivars from three different farming systems (organic, biodynamic, and conventional). Strains able to inhibit or slow the growth of pathogens were selected by in vitro and in vivo experiments. The most effective antagonist yeast strains were subsequently assayed for their capability to colonize the grape berries. Finally, possible modes of action, such as nutrients and space competition, iron depletion, cell wall degrading enzymes, diffusible and volatile antimicrobial compounds, and biofilm formation, were investigated as well. Two hundred and thirty-one yeast strains belonging to 26 different species were isolated; 20 of them, ascribed to eight species, showed antagonistic action against all molds. Yeasts isolated from V. vinifera ssp sylvestris were more effective (up to 50%) against B. cinerea rather than those isolated from V. vinifera ssp vinifera. Six strains, all isolated from wild vines, belonging to four species ( Meyerozyma guilliermondii, Hanseniaspora uvarum, Hanseniaspora clermontiae , and Pichia kluyveri ) revealed one or more phenotypical characteristics associated to the analyzed modes of antagonistic action.

Biocontrol and plant growth promoting activities of a Streptomyces corchorusii strain UCR3-16 and preparation of powder formulation for application as biofertilizer agents for rice plant.

PubMed

Tamreihao, K; Ningthoujam, Debananda S; Nimaichand, Salam; Singh, Elangbam Shanta; Reena, Pascal; Singh, Salam Herojeet; Nongthomba, Upendra

2016-11-01

Streptomyces corchorusii strain UCR3-16, obtained from rice rhizospheric soils showed antifungal activities against 6 major rice fungal pathogens by diffusible and volatile compounds production. The strain was found positive for production of fungal cell wall degrading enzymes such as chitinase, β-1,3-glucanase, β-1,4-glucanase, lipase and protease. The strain was also positive for plant growth promoting traits. It produced up to 30.5μg/ml of IAA and solubilized a significant amount of inorganic phosphate (up to 102μg/ml). It also produced 69% siderophore units. The strain also produced ammonia and gave positive result for ACC deaminase activity. Highest vigor index of inoculated seedlings was observed when rice seeds were treated with cell suspension of UCR3-16 corresponding to 4.5×10(8)cfu/ml. Bioinoculant-treated seeds also showed similar results under pathogen challenged conditions. In pot trial experiments, UCR3-16-treated rice plants showed significantly increased growth and grain yield production. Powder formulation of the strain was developed using talcum and corn starch as carriers and the shelf-lives were monitored. Talcum formulation showed higher cell-count than corn starch even after 6 months of storage, and optimum condition for storage of the powder formulation were found to be at 4°C. Pot trial experiments using talcum powder formulation also showed significant positive effects on growth of rice plants. Field trial using talcum powder formulation also exhibited significant enhancement in shoot length and weight of shoot and root, and total grain yield and weight of grains in rice plants. Talcum formulation also significantly reduced the sheath blight disease in rice leaves. Copyright © 2016. Published by Elsevier GmbH.

Generation of Trichoderma atroviride mutants with constitutively activated G protein signaling by using geneticin resistance as selection marker.

PubMed

Gruber, Sabine; Omann, Markus; Rodrìguez, Carolina Escobar; Radebner, Theresa; Zeilinger, Susanne

2012-11-17

Species of the fungal genus Trichoderma are important industrial producers of cellulases and hemicellulases, but also widely used as biocontrol agents (BCAs) in agriculture. In the latter function Trichoderma species stimulate plant growth, induce plant defense and directly antagonize plant pathogenic fungi through their mycoparasitic capabilities. The recent release of the genome sequences of four mycoparasitic Trichoderma species now forms the basis for large-scale genetic manipulations of these important BCAs. Thus far, only a limited number of dominant selection markers, including Hygromycin B resistance (hph) and the acetamidase-encoding amdS gene, have been available for transformation of Trichoderma spp. For more extensive functional genomics studies the utilization of additional dominant markers will be essential. We established the Escherichia coli neomycin phosphotransferase II-encoding nptII gene as a novel selectable marker for the transformation of Trichoderma atroviride conferring geneticin resistance. The nptII marker cassette was stably integrated into the fungal genome and transformants exhibited unaltered phenotypes compared to the wild-type. Co-transformation of T. atroviride with nptII and a constitutively activated version of the Gα subunit-encoding tga3 gene (tga3Q207L) resulted in a high number of mitotically stable, geneticin-resistant transformants. Further analyses revealed a co-transformation frequency of 68% with 15 transformants having additionally integrated tga3Q207L into their genome. Constitutive activation of the Tga3-mediated signaling pathway resulted in increased vegetative growth and an enhanced ability to antagonize plant pathogenic host fungi. The neomycin phosphotransferase II-encoding nptII gene from Escherichia coli proved to be a valuable tool for conferring geneticin resistance to the filamentous fungus T. atroviride thereby contributing to an enhanced genetic tractability of these important BCAs.

Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens

PubMed Central

Cordero-Bueso, Gustavo; Mangieri, Nicola; Maghradze, David; Foschino, Roberto; Valdetara, Federica; Cantoral, Jesús M.; Vigentini, Ileana

2017-01-01

The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinerea, Aspergillus carbonarius, and Penicillium expansum pathogen species. In particular, yeast isolation was carried out from grape berries of Vitis vinifera ssp sylvestris populations, of the Eurasian area, and V. vinifera ssp vinifera cultivars from three different farming systems (organic, biodynamic, and conventional). Strains able to inhibit or slow the growth of pathogens were selected by in vitro and in vivo experiments. The most effective antagonist yeast strains were subsequently assayed for their capability to colonize the grape berries. Finally, possible modes of action, such as nutrients and space competition, iron depletion, cell wall degrading enzymes, diffusible and volatile antimicrobial compounds, and biofilm formation, were investigated as well. Two hundred and thirty-one yeast strains belonging to 26 different species were isolated; 20 of them, ascribed to eight species, showed antagonistic action against all molds. Yeasts isolated from V. vinifera ssp sylvestris were more effective (up to 50%) against B. cinerea rather than those isolated from V. vinifera ssp vinifera. Six strains, all isolated from wild vines, belonging to four species (Meyerozyma guilliermondii, Hanseniaspora uvarum, Hanseniaspora clermontiae, and Pichia kluyveri) revealed one or more phenotypical characteristics associated to the analyzed modes of antagonistic action. PMID:29163377

Management of blight of bell pepper (Capsicum annuum var. grossum) caused by Drechslera bicolor.

PubMed

Jadon, Kuldeep Singh; Shah, Rakesh; Gour, Hari Narayan; Sharma, Pankaj

Sweet or bell pepper is a member of the Solanaceae family and is regarded as one of the most popular and nutritious vegetable. Blight, in the form of leaf and fruit blight, has been observed to infect bell pepper crops cultivated at the horticulture farm in Rajasthan College of Agriculture, Udaipur, India. Based on disease severity, we attempted to curb this newly emerged problem using different fungicides, plant extracts, bio-control agents, and commercial botanicals against the fungus in laboratory and pot experiments. Bio-control agent Trichoderma viride and plant growth promoting Rhizobacteria (PGPR) isolate Neist-2 were found to be quite effective against bell pepper blight. All evaluated fungicides, botanicals, commercial botanicals, and bio-control agents in vitro were further studied as seed dressers and two foliar sprays at ten days interval in pot experiments. The combinations of Vitavax, PGPR isolate Neist-2, and Mehandi extract were found to be very effective against bell pepper blight followed by Vitavax, T. viride, and Mehandi extract used individually. All treatments in the pot experiments were found to significantly reduce seedling mortality and enhance plant biomass of bell pepper. Thus, these experimental findings suggest that a better integrated management of bell pepper blight could be achieved by conducting field trials in major bell pepper- and chilli-cultivated areas of the state. Besides fungicides, different botanicals and commercial botanicals also seem to be promising treatment options. Therefore, the outcome of the present study provides an alternate option of fungicide use in minimizing loss caused by Drechslera bicolor. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Formulation development of the biocontrol agent Bacillus subtilis strain CPA-8 by spray-drying.

PubMed

Yánez-Mendizábal, V; Viñas, I; Usall, J; Torres, R; Solsona, C; Abadias, M; Teixidó, N

2012-05-01

To prepare commercially acceptable formulations of Bacillus subtilis CPA-8 by spray-drying with long storage life and retained efficacy to control peach and nectarine brown rot caused by Monilinia spp. CPA-8 24-h- and 72-h-old cultures were spray dried using 10% skimmed milk, 10% skimmed milk plus 10% MgSO(4) , 10% MgSO(4) and 20% MgSO(4) as carriers/protectants. All carriers/protectants gave good percentages of powder recovery (28-38%) and moisture content (7-13%). CPA-8 survival varied considerably among spray-dried 24-h- and 72-h-old cultures. Seventy-two hours culture spray dried formulations showed the highest survival (28-32%) with final concentration products of 1·6-3·3 × 10(9) CFU g(-1) , while viability of 24-h-old formulations was lower than 1%. Spray-dried 72-h-old formulations were selected to subsequent evaluation. Rehydration of cells with water provided a good recovery of CPA-8 dried cells, similar to other complex rehydration media tested. Spray-dried formulations stored at 4 ± 1 and 20 ± 1°C showed good shelf life during 6 months, and viability was maintained or slightly decreased by 0·2-0·3-log. CPA-8 formulations after 4- and 6 months storage were effective in controlling brown rot caused by Monilinia spp. on nectarines and peaches resulting in a 90-100% reduction in disease incidence. Stable and effective formulations of biocontrol agent B. subtilis CPA-8 could be obtained by spray-drying. New shelf-stable and effective formulations of a biocontrol agent have been obtained by spray-drying to control brown rot on peach. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Manipulating the banana rhizosphere microbiome for biological control of Panama disease.

PubMed

Xue, Chao; Penton, C Ryan; Shen, Zongzhuan; Zhang, Ruifu; Huang, Qiwei; Li, Rong; Ruan, Yunze; Shen, Qirong

2015-08-05

Panama disease caused by Fusarium oxysporum f. sp. cubense infection on banana is devastating banana plantations worldwide. Biological control has been proposed to suppress Panama disease, though the stability and survival of bio-control microorganisms in field setting is largely unknown. In order to develop a bio-control strategy for this disease, 16S rRNA gene sequencing was used to assess the microbial community of a disease-suppressive soil. Bacillus was identified as the dominant bacterial group in the suppressive soil. For this reason, B. amyloliquefaciens NJN-6 isolated from the suppressive soil was selected as a potential bio-control agent. A bioorganic fertilizer (BIO), formulated by combining this isolate with compost, was applied in nursery pots to assess the bio-control of Panama disease. Results showed that BIO significantly decreased disease incidence by 68.5%, resulting in a doubled yield. Moreover, bacterial community structure was significantly correlated to disease incidence and yield and Bacillus colonization was negatively correlated with pathogen abundance and disease incidence, but positively correlated to yield. In total, the application of BIO altered the rhizo-bacterial community by establishing beneficial strains that dominated the microbial community and decreased pathogen colonization in the banana rhizosphere, which plays an important role in the management of Panama disease.

Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape.

PubMed

Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

2015-05-01

Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape. Copyright © 2014 Elsevier Ltd. All rights reserved.

Manipulating the banana rhizosphere microbiome for biological control of Panama disease

PubMed Central

Xue, Chao; Ryan Penton, C.; Shen, Zongzhuan; Zhang, Ruifu; Huang, Qiwei; Li, Rong; Ruan, Yunze; Shen, Qirong

2015-01-01

Panama disease caused by Fusarium oxysporum f. sp. cubense infection on banana is devastating banana plantations worldwide. Biological control has been proposed to suppress Panama disease, though the stability and survival of bio-control microorganisms in field setting is largely unknown. In order to develop a bio-control strategy for this disease, 16S rRNA gene sequencing was used to assess the microbial community of a disease-suppressive soil. Bacillus was identified as the dominant bacterial group in the suppressive soil. For this reason, B. amyloliquefaciens NJN-6 isolated from the suppressive soil was selected as a potential bio-control agent. A bioorganic fertilizer (BIO), formulated by combining this isolate with compost, was applied in nursery pots to assess the bio-control of Panama disease. Results showed that BIO significantly decreased disease incidence by 68.5%, resulting in a doubled yield. Moreover, bacterial community structure was significantly correlated to disease incidence and yield and Bacillus colonization was negatively correlated with pathogen abundance and disease incidence, but positively correlated to yield. In total, the application of BIO altered the rhizo-bacterial community by establishing beneficial strains that dominated the microbial community and decreased pathogen colonization in the banana rhizosphere, which plays an important role in the management of Panama disease. PMID:26242751

The science, development, and commercialization of postharvest biocontrol products

USDA-ARS?s Scientific Manuscript database

Postharvest biological control agents as a viable alternative to the use of synthetic chemicals have been the focus of considerable research for the last 30 years by many scientists and several commercial companies worldwide. Several antagonists of postharvest pathogens have been identified and tes...

Purification and host specificity of predatory halobacteriovorax isolated from seawater

USDA-ARS?s Scientific Manuscript database

Halobacteriovorax (formerly Bacteriovorax) are small predatory bacteria found in the marine environment and may serve as biocontrol agents against pathogens in fish and shellfish. Four strains of Halobacteriovorax originally isolated in Vibrio parahaemolyticus O3:K6 host cells were separated from t...

Application of biocontrol agents in forest nurseries

USDA-ARS?s Scientific Manuscript database

Bare-root conifer seedling culture consists of growing seedlings (sown or transplanted) in soil, and is the predominant method for supplying America’s need for healthy regeneration stock to produce and sustain forests, wildlife food sources, fiber, wood products, paper, bio-pharmaceuticals and now p...

Two species of Gelechioidea (Lepidoptera) from Southeast Asia associated with downy rose myrtle, Rhodomyrtus tomentosa (Myrtaceae)

USDA-ARS?s Scientific Manuscript database

Two species of Gelechioidea (Lepidoptera), Metharmostis multilineata Adamski, n. sp. (Cosmopterigidae), and Idiophantis soreuta Meyrick, 1906 (Gelechiidae), were collected in southeastern Asia for evaluation as potential biocontrol agents against downy rose myrtle, Rhodomyrtus tomentosa (Aiton) Hass...

Are plant trichomes harmful to predatory insects and mites?

USDA-ARS?s Scientific Manuscript database

Plants may use epidermal hairs (trichomes) to defend themselves from attack by herbivores. Predatory arthropods may serve as biocontrol agents against herbivores. Whether or not plant trichomes work in concert with predators is undocumented in many cases. We reviewed the peer-reviewed literature ...

Trichoderma secondary metabolites that affect plant metabolism.

PubMed

Vinale, Francesco; Sivasithamparam, Krishnapillai; Ghisalberti, Emilio L; Ruocco, Michelina; Wood, Sheridan; Lorito, Matteo

2012-11-01

Recently, there have been many exciting new developments relating to the use of Trichoderma spp. as agents for biocontrol of pathogens and as plant growth promoters. Several mechanisms have been proposed to explain the positive effects of these microorganisms on the plant host. One factor that contributes to their beneficial biological activities is related to the wide variety of metabolites that they produce. These metabolites have been found not only to directly inhibit the growth and pathogenic activities of the parasites, but also to increase disease resistance by triggering the system of defence in the plant host. In addition, these metabolites are also capable of enhancing plant growth, which enables the plant to counteract the disease with compensatory vegetative growth by the augmented production of root and shoot systems. This review takes into account the Trichoderma secondary metabolites that affect plant metabolism and that may play an important role in the complex interactions of this biocontrol agent with the plant and pathogens.

Saccharomyces cerevisiae: A novel and efficient biological control agent for Colletotrichum acutatum during pre-harvest.

PubMed

Lopes, Marcos Roberto; Klein, Mariana Nadjara; Ferraz, Luriany Pompeo; da Silva, Aline Caroline; Kupper, Katia Cristina

2015-06-01

In this study, we evaluated the efficiency of six isolates of Saccharomyces cerevisiae in controlling Colletotrichum acutatum, the causal agent of postbloom fruit drop that occur in pre-harvest citrus. We analyzed the mechanisms of action involved in biological control such as: production of antifungal compounds, nutrient competition, detection of killer activity, and production of hydrolytic enzymes of the isolates of S. cerevisiae on C. acutatum and their efficiency in controlling postbloom fruit drop on detached citrus flowers. Our results showed that all six S. cerevisiae isolates produced antifungal compounds, competed for nutrients, inhibited pathogen germination, and produced killer activity and hydrolytic enzymes when in contact with the fungus wall. The isolates were able to control the disease when detached flowers were artificially inoculated, both preventively and curatively. In this work we identified a novel potential biological control agent for C. acutatum during pre-harvest. This is the first report of yeast efficiency for the biocontrol of postbloom fruit drop, which represents an important contribution to the field of biocontrol of diseases affecting citrus populations worldwide. Copyright © 2015 Elsevier GmbH. All rights reserved.

Effect of fluorescent pseudomonades and Trichoderma sp. and their combination with two chemicals on Penicillium digitatum caused agent of citrus green mold.

PubMed

Zamani, M; Tehrani, A Sharifi; Ahmadzadeh, M; Abadi, A Alizadeh Ali

2006-01-01

Citrus green mold (Penicillium digitatum) causes economic losses. Chemical fungicides such as imazalil provide the primary means for controlling green mold decay of citrus fruits. Continuous use of fungicides has faced two major obstacles- increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The aim of this research was to determine if the attacks of green mold on orange could be reduced by usage of biocontrol agent alone or in combination with low dosage of imazalil or sodium bicarbonate. Pseudomonas fluorescens isolate PN, P. fluorescens isolate PS and Trichoderma virens isolate TE were evaluated as potential biological agents for control of green mold of oranges caused by P. digitatum. Increasing concentration of SB decreased spore germination of P. digitatum. In laboratory tests, a cell suspension (10(8) cells per ml.) of bacterial strains reduced the incidence of green mold. On fruits surface biocontrol activity of antagonistic isolates was significantly increased when combined with low dosage of imazalil (500ppm) or sodium carbonate (5%). Effect of Trichoderma virens on controlling P. digitatum was better than others with or without these chemicals.

El control biologico de plagas(Biological control of pests)

USDA-ARS?s Scientific Manuscript database

In this work some ecological principles that drive applied biocontrol and agent selection are discussed. Subjects such as specificity evaluations, host shifts and species invasiveness are analyzed under the light of ecological theory. The main assertions are: 1. biological control is a safe and bene...

Endophytic Fungi in a Hordeum Germplasm Collection

Treesearch

A. Dan Wilson; S.L. Clement; W.J. Kaiser

1991-01-01

The incidence of clavicipitaceous anamorphic endophytes in a Hordeum spp. germplasm collection is reported. The potential application of endophytes as biocontrol agents against pests of cereal crops is recognized. Suggestions are proposed to modify existing germplasm maintenance procedures to ensure that both seed viability and endophyte viability...

Potential of predatory bacteria as biocontrol agents for foodborne and plant pathogens

USDA-ARS?s Scientific Manuscript database

Foodborne pathogens such as Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, Shigella are responsible for frequent occurrences of illnesses and mortality in humans and produce losses. Pre-harvest yield losses and post-harvest decay on minimally processed produce (fruits, vegetables...

Evaluation of Atoxigenic Strains of Aspergillus flavus as Potential Biocontrol Agents for Aflatoxin in Maize

USDA-ARS?s Scientific Manuscript database

Aflatoxin contamination resulting from maize infection by Aspergillus flavus is both an economic concern and public health concern. Therefore, strategies for controlling maize contamination are being investigated. Abilities of 11 naturally occurring atoxigenic strains in Nigeria to reduce aflatox...

POSSIBLE ROLE OF FUNGAL HEMOLYSINS IN SICK BUILDING SYNDROME

EPA Science Inventory

Many fungi produce proteinaceous hemolytic agents. Like bacterial hemolysins, fungal hemolysins create pores or holes in membranes. Depending on which membranes are damaged, fungal hemolysins can produce a variety of effects. Fungal hemolysins can cause histamine release from ...

Multiple introductions and recombination in Cryphonectria hypovirus 1: perspective for a sustainable biological control of chestnut blight

PubMed Central

Feau, Nicolas; Dutech, Cyril; Brusini, Jérémie; Rigling, Daniel; Robin, Cécile

2014-01-01

Cryphonectria hypovirus 1 (CHV1) is a mycovirus which decreases the virulence of its fungal host Cryphonectria parasitica, the causal agent of chestnut blight recently introduced in Europe. The understanding of the evolutionary processes which have shaped CHV1 populations in Europe is required to develop a sustainable biocontrol strategy targeting chestnut blight and effective in European chestnut forests. To retrace the evolutionary history of CHV1, we analyzed sequences from two genomic regions on a collection of 55 CHV1 strains from France and northern Spain, two countries where multiple introductions of C. parasitica occurred. Several recombination events and variable selection pressures contributed to CHV1 evolution, agreeing with a non-clock-like diversification rate. These two mechanisms may be at the origin of CHV1 population diversity observed in western Europe. Considering the actual prevalence of CHV1 and its association with host genotypes, multiple introductions of CHV1 may have occurred in Europe, some of them directly from Asia and some of them through North America. Although some viral strains remained with low frequency in their introduction area, multiple infections might have allowed homologous recombination within parental sequences. Some of these recombinant lineages are associated with the spread of CHV1 in European regions. PMID:24944571

Identification of an antifungal metabolite produced by a potential biocontrol Actinomyces strain A01

PubMed Central

Lu, Cai Ge; Liu, Wei Cheng; Qiu, Ji Yan; Wang, Hui Min; Liu, Ting; De Liu, Wen

2008-01-01

Actinomyces strain A01 was isolated from soil of a vegetable field in the suburb of Beijing, China. According to the morphological, cultural, physiological and biochemical characteristics, and 16S rDNA sequence analysis, strain A01 was identified as Streptomyces lydicus. In the antimicrobial spectrum test strain A01 presented a stable and strong inhibitory activity against several plant pathogenic fungi such as Fusarium oxysporum, Botrytis cinerea, Monilinia laxa, etc. However, no antibacterial activity was found. In pot experiments in greenhouse, the development of tomato gray mold was markedly suppressed by treatment with the fermentation broth of the strain A01, and the control efficacy was higher than those of Pyrimethanil and Polyoxin. A main antifungal compound (purity 99.503%) was obtained from the fermentation broth of strain A01 using column chromatography and HPLC. The chemical structural analysis with U V, IR, MS, and NMR confirmed that the compound produced by the strain A01 is natamycin, a polyene antibiotic produced by S. chattanovgensis, S. natalensis, and S. gilvosporeus, widely used as a natural biological preservative for food according to previous reports. The present study revealed a new producing strain of natamycin and its potential application as a biological control agent for fungal plant diseases. PMID:24031293

Co-Culture of Plant Beneficial Microbes as Source of Bioactive Metabolites.

PubMed

Vinale, F; Nicoletti, R; Borrelli, F; Mangoni, A; Parisi, O A; Marra, R; Lombardi, N; Lacatena, F; Grauso, L; Finizio, S; Lorito, M; Woo, S L

2017-10-30

In microbial cultures the production of secondary metabolites is affected by experimental conditions, and the discovery of novel compounds is often prevented by the re-isolation of known metabolites. To limit this, it is possible to cultivate microorganisms by simulating naturally occurring interactions, where microbes co-exist in complex communities. In this work, co-culturing experiments of the biocontrol agent Trichoderma harzianum M10 and the endophyte Talaromyces pinophilus F36CF have been performed to elicit the expression of genes which are not transcribed in standard laboratory assays. Metabolomic analysis revealed that the co-culture induced the accumulation of siderophores for both fungi, while production of M10 harzianic and iso-harzianic acids was not affected by F36CF. Conversely, metabolites of the latter strain, 3-O-methylfunicone and herquline B, were less abundant when M10 was present. A novel compound, hereby named harziaphilic acid, was isolated from fungal co-cultures, and fully characterized. Moreover, harzianic and harziaphilic acids did not affect viability of colorectal cancer and healthy colonic epithelial cells, but selectively reduced cancer cell proliferation. Our results demonstrated that the co-cultivation of plant beneficial fungi may represent an effective strategy to modulate the production of bioactive metabolites and possibly identify novel compounds.

Use of the Endophytic Fungus Daldinia cf. concentrica and Its Volatiles as Bio-Control Agents

PubMed Central

Liarzi, Orna; Bar, Einat; Lewinsohn, Efraim; Ezra, David

2016-01-01

Endophytic fungi are organisms that spend most of their life cycle within plant tissues without causing any visible damage to the host plant. Many endophytes were found to secrete specialized metabolites and/or emit volatile organic compounds (VOCs), which may be biologically active and assist fungal survival inside the plant as well as benefit their hosts. We report on the isolation and characterization of a VOCs-emitting endophytic fungus, isolated from an olive tree (Olea europaea L.) growing in Israel; the isolate was identified as Daldinia cf. concentrica. We found that the emitted VOCs were active against various fungi from diverse phyla. Results from postharvest experiments demonstrated that D. cf. concentrica prevented development of molds on organic dried fruits, and eliminated Aspergillus niger infection in peanuts. Gas chromatography–mass spectrometry analysis of the volatiles led to identification of 27 VOCs. On the basis of these VOCs we prepared two mixtures that displayed a broad spectrum of antifungal activity. In postharvest experiments these mixtures prevented development of molds on wheat grains, and fully eliminated A. niger infection in peanuts. In light of these findings, we suggest use of D. cf. concentrica and/or its volatiles as an alternative approach to controlling phytopathogenic fungi in the food industry and in agriculture. PMID:27977739

Some fungal endophytes from vegetable crops and their anti-oomycete activities against tomato late blight.

PubMed

Kim, H-Y; Choi, G J; Lee, H B; Lee, S-W; Lim, H K; Jang, K S; Son, S W; Lee, S O; Cho, K Y; Sung, N D; Kim, J-C

2007-03-01

To isolate endophytic fungi from vegetable plants and examine their in vivo anti-oomycete activity against Phytophthora infestans in tomato plants. Endophytic fungi were isolated from surface-sterilized plant tissues and anti-oomycete activity was measured by in vivo assay using tomato seedlings. Endophytic fungi showing potent anti-oomycete activity were identified by morphological characteristics and nuclear ribosomal ITS1-5.8S-ITS2 sequence analysis. A total of 152 isolates were obtained from 66 healthy tissue samples of cucumber, red pepper, tomato, pumpkin and Chinese cabbage and the fermentation broths of 23 isolates showed potent in vivo anti-oomycete activity against tomato late blight with control values over 90%. The Fusarium oxysporum strain EF119, which was isolated from roots of red pepper, showed the most potent disease control efficacy against tomato late blight. In dual-culture tests, it inhibited the growth of Pythium ultimum, P. infestans and Phytophthora capsici. Among endophytic fungi isolated from healthy tissues of vegetable plants, F. oxysporum EF119 showed the most potent in vivo anti-oomycete activity against tomato late blight and in vitro anti-oomycete activity against several oomycete pathogens. Endophytic fungi showing anti-oomycete activity in vitro and in vivo may be used as biocontrol agents particularly of tomato late blight.

Effect of certain entomopathogenic fungi on oxidative stress and mortality of Periplaneta americana.

PubMed

Chaurasia, Abhilasha; Lone, Yaqoob; Wani, Owais; Gupta, U S

2016-02-01

The present paper reports the effects of Metarhizium anisopliae, Isaria fumosoroseus and Hirsutella thompsonaii on Periplaneta americana. I. fumosoroseus and H. thompsonaii were cultured at 28±1°C on potato carrot agar and M. anisopliae was cultured at 28±1°C on potato dextrose agar for 14days. Conidial suspensions of fungi were given to cockroaches through different routes. M. anisopliae shows high virulence against adult cockroaches and mortality ranges from 38.65% to 78.36% after 48h. I. fumosoroseus and H. thompsonii show less virulence compared to M. anisopliae. We also investigated the effect of these three fungi on the activity of lactate dehydrogenase, lipid peroxidation and catalase in different tissues of the insect to gain an understanding of the different target site. The result suggested that the activity of lactate dehydrogenase, catalase and level of malondialdehyde varies in different organs and through different routes of exposure. Based on mortality percentages, all tested fungi had high potentials for biocontrol agents against P. americana. Our study reveals for the first time that I. fumosoroseus and H. thompsonaii fungal infections initiate oxidative stress in the midgut, fat body, whole body and hemolymph of cockroach thereby suggesting them to be the target organs for oxidative damage. Copyright © 2015 Elsevier B.V. All rights reserved.

Lactobacillus plantarum with Broad Antifungal Activity as a Protective Starter Culture for Bread Production

PubMed Central

Russo, Pasquale; Longo, Angela; Spano, Giuseppe; Capozzi, Vittorio

2017-01-01

Bread is a staple food consumed worldwide on a daily basis. Fungal contamination of bread is a critical concern for producers since it is related to important economic losses and safety hazards due to the negative impact of sensorial quality and to the potential occurrence of mycotoxins. In this work, Lactobacillus plantarum UFG 121, a strain with characterized broad antifungal activity, was analyzed as a potential protective culture for bread production. Six different molds belonging to Aspergillus spp., Penicillium spp., and Fusarium culmorum were used to artificially contaminate bread produced with two experimental modes: (i) inoculation of the dough with a commercial Saccharomyces cerevisiae strain (control) and (ii) co-inoculation of the dough with the commercial S. cerevisiae strain and with L. plantarum UFG 121. L. plantarum strain completely inhibited the growth of F. culmorum after one week of storage. The lactic acid bacterium modulated the mold growth in samples contaminated with Aspergillus flavus, Penicillium chrysogenum, and Penicillium expansum, while no antagonistic effect was found against Aspergillus niger and Penicillium roqueforti. These results indicate the potential of L. plantarum UFG 121 as a biocontrol agent in bread production and suggest a species- or strain-depending sensitivity of the molds to the same microbial-based control strategy. PMID:29232917

Dry formulations of the biocontrol agent Candida sake CPA-1 using fluidised bed drying to control the main postharvest diseases on fruits.

PubMed

Carbó, Anna; Torres, Rosario; Usall, Josep; Fons, Estanislau; Teixidó, Neus

2017-08-01

The biocontrol agent Candida sake CPA-1 is effective against several diseases. Consequently, the optimisation of a dry formulation of C. sake to improve its shelf life and manipulability is essential for increasing its potential with respect to future commercial applications. The present study aimed to optimise the conditions for making a dry formulation of C. sake using a fluidised bed drying system and then to determine the shelf life of the optimised formulation and its efficacy against Penicillium expansum on apples. The optimal conditions for the drying process were found to be 40 °C for 45 min and the use of potato starch as the carrier significantly enhanced the viability. However, none of the protective compounds tested increased the viability of the dried cells. A temperature of 25 °C for 10 min in phosphate buffer was considered as the optimum condition to recover the dried formulations. The dried formulations should be stored at 4 °C and air-packaged; moreover, shelf life assays indicated good results after 12 months of storage. The formulated products maintained their biocontrol efficacy. A fluidised bed drying system is a suitable process for dehydrating C. sake cells; moreover, the C. sake formulation is easy to pack, store and transport, and is a cost-effective process. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases.

PubMed

Calvo, H; Marco, P; Blanco, D; Oria, R; Venturini, M E

2017-05-01

The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 10 7  CFU mL -1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast, Pichia anomala, for aflatoxin reduction.

PubMed

Hua, Sui Sheng T; Hernlem, Bradley J; Yokoyama, Wallace; Sarreal, Siov Bouy L

2015-05-01

Pichia anomala (Wickerhamomyces anomalus) WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of aflatoxin in the food chain. Maintaining the viability of biocontrol agents in formulated products is a great challenge for commercial applications. Four media, NYG, NYGS, NYGT and NYGST are described which support good growth of yeast cells and were tested as storage formulations. Post growth supplement of 5 % trehalose to NYGST resulted in 83 % viable yeast cells after 12 months in cold storage. Intracellular sorbitol and trehalose concentrations were determined by HPLC analysis at the beginning of the storage and at the end of 12 month. Correlation of cell viability to both trehalose and sorbitol suggested a synergistic effect. Bonferroni (Dunn) t Test, Tukey's Studentized Range (HSD) Test and Duncan's Multiple Range Test, all showed that yeast cell viability in samples with both intracellular trehalose and sorbitol were significantly higher than those with either or none, at a 95 % confidence level. DiBAC4(5) and CFDA-AM were used as the membrane integrity fluorescent stains to create a two-color vital staining scheme with red and green fluorescence, respectively. Yeast cells stored in formulations NYG and NYGS with no detectable trehalose, displayed mostly red fluorescence. Yeast cells in NYGST+5T showed mostly green fluorescence.

Impact of mild heat treatments on induction of thermotolerance in the biocontrol yeast Candida sake CPA-1 and viability after spray-drying.

PubMed

Cañamás, T P; Viñas, I; Usall, J; Magan, N; Solsona, C; Teixidó, N

2008-03-01

The objective of this study was to examine the induction of thermotolerance in the biocontrol agent Candida sake CPA-1 cells by mild heat treatments to enhanced survival of formulations using spray-drying. The possible role of heat-shock proteins (HSPs) biosynthesis in induced thermotolerance and the role of sugars and sugar alcohols were also determined. Studies were conducted on C. sake cells grown in molasses medium and exposed to mild temperatures of 30 and 33 degrees C during mid- (16 h), late-exponential (24 h), early- (30 h) and mid-stationary (36 h) growth phases. The effect on viability was determined both before and after spray-drying. Cycloheximide and chloramphenicol were used to examine the role of HSPs and HPLC was used to analyse the accumulation of sugar and sugar alcohols. The results indicate that both temperatures induced thermotolerance in cells of C. sake. Mild heat-adapted cells at 33 degrees C in the early- or mid-stationary phases had survival values after spray-drying significantly higher (P

Research on Volatile Organic Compounds From Bacillus subtilis CF-3: Biocontrol Effects on Fruit Fungal Pathogens and Dynamic Changes During Fermentation

PubMed Central

Gao, Haiyan; Li, Peizhong; Xu, Xinxing; Zeng, Qing; Guan, Wenqiang

2018-01-01

The dynamic changes of the levels of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 and their biocontrol effects on common fungal pathogens were researched in this study. The results showed that the VOCs in 24-h fermentation liquid (24hFL) of B. subtilis CF-3 inhibited mycelial growth of Botrytis cinerea, Colletotrichum gloeosporioides, Penicillium expansum, Monilinia fructicola, and Alternaria alternata, with a mean inhibition rate of 59.97%. The inhibitory effect on M. fructicola and C. gloeosporioides was the highest; they were therefore selected as target fungal pathogens for further experiments. Based on headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), 74 potential VOCs were identified during the fermentation: 15 alcohols, 18 ketones, 4 pyrazines, 4 esters, 10 acids, 5 phenols, 3 hydrocarbons, 3 amines, 2 aldehydes, 5 ethers, and 5 other components. At different fermentation times, the type and content of VOCs were different. Most of the potential VOCs (62 VOCs) were identified in the 48hFL. The inhibition rates of all VOCs reached their peaks (73.46% on M. fructicola and 63.63% on C. gloeosporioides) in the 24hFL. Among the identified VOCs, 2,4-di-tert-butylphenol, 1-octanol, and benzothiazole showed significant positive correlations with the rates of M. fructicola and C. gloeosporioides inhibition. Benzoic acid and benzaldehyde showed a significant positive correlation with the rates of M. fructicola inhibition, and anisole and 3-methylbutanal showed a significant positive correlation with the rates of C. gloeosporioides inhibition. In vitro, 2,4-di-tert-butylphenol showed a strong inhibitory effect on both M. fructicola and C. gloeosporioides. In vivo, benzothiazole showed the strongest inhibitory effect on the mycelial extensions of both M. fructicola and C. gloeosporioides, which also led to an increased rate of healthy fruit. The results of the present study clarified that 2,4-di-tert-butylthiophenol and benzothiazole are key inhibitory VOCs produced by B. subtilis CF-3. PMID:29593695

A Field Experiment to Assess the Rate of Infestation in Honey Bee Populations of Two Metarhizium anisopliae Isolates on Varroa destructor (Acari: Mesostigmata).

PubMed

Pirali-Kheirabadi, Khodadad; Teixeira-da-Silva, Jaime A; Razzaghi-Abyaneh, Mehdi; Nazemnia, Mehdi

2013-01-01

The protective effect of two isolates of an entomopathogenic fungus, Metarhizium anisopliae (DEMI 002 and Iran 437C) on the adult stage of Varroa destructor was evaluated in comparison with fluvalinate strips in the field. A total of 12 honey bee colonies were provided from an apiculture farm. The selected hives were divided into 4 groups (3 hives per group). The first group was the control, treated with distilled water. The other two groups were exposed to different fungi (M. anisopliae isolates DEMI 002 and Iran 437C) and the last group was treated with one strip of fluvalinate per colony. The number of fallen mites was counted using sticky traps during a 6-day period, six days before and after treatments. A fungal suspension at a concentration of 5× 10(6) conidia/mL was sprayed onto the frames and the number of fallen mites was counted. Metarhizium anisopliae DEMI 002 and Iran 437C isolates were as effective (i.e., caused as much mite fall) as the fluvalinate strip in controlling bee colonies than no treatment. Both M. anisopliae isolates are promising candidates as agents in the control of Varroa mites under field conditions. Isolate DEMI 002 can be considered as a possible non-chemical biocontrol agent for controlling bee infestation with V. destructor in the field. In order to substantiate this hypothesis, tests are currently being performed using larger colonies and larger doses than tested in the present study in our beekeeping.

A Field Experiment to Assess the Rate of Infestation in Honey Bee Populations of Two Metarhizium anisopliae Isolates on Varroa destructor (Acari: Mesostigmata)

PubMed Central

Pirali-kheirabadi, Khodadad; Teixeira-da-Silva, Jaime A; Razzaghi-Abyaneh, Mehdi; Nazemnia, Mehdi

2013-01-01

Background: The protective effect of two isolates of an entomopathogenic fungus, Metarhizium anisopliae (DEMI 002 and Iran 437C) on the adult stage of Varroa destructor was evaluated in comparison with fluvalinate strips in the field. Methods: A total of 12 honey bee colonies were provided from an apiculture farm. The selected hives were divided into 4 groups (3 hives per group). The first group was the control, treated with distilled water. The other two groups were exposed to different fungi (M. anisopliae isolates DEMI 002 and Iran 437C) and the last group was treated with one strip of fluvalinate per colony. The number of fallen mites was counted using sticky traps during a 6-day period, six days before and after treatments. A fungal suspension at a concentration of 5× 106 conidia/mL was sprayed onto the frames and the number of fallen mites was counted. Results: Metarhizium anisopliae DEMI 002 and Iran 437C isolates were as effective (i.e., caused as much mite fall) as the fluvalinate strip in controlling bee colonies than no treatment. Conclusion: Both M. anisopliae isolates are promising candidates as agents in the control of Varroa mites under field conditions. Isolate DEMI 002 can be considered as a possible non-chemical biocontrol agent for controlling bee infestation with V. destructor in the field. In order to substantiate this hypothesis, tests are currently being performed using larger colonies and larger doses than tested in the present study in our beekeeping. PMID:23785691

Biological interactions to select biocontrol agents against toxigenic strains of Aspergillus flavus and Fusarium verticillioides from maize.

PubMed

Etcheverry, Miriam G; Scandolara, Andrea; Nesci, Andrea; Vilas Boas Ribeiro, Marta Sofia; Pereira, Paola; Battilani, Paola

2009-05-01

Biological control represent an alternative to the use of pesticides in crop protection. A key to progress in biological control to protect maize against Fusarium verticillioides and Aspergillus flavus maize pathogens are, to select in vitro, the best agent to be applied in the field. The aim of this study was to examine the antagonistic activity of bacterial and yeast isolates against F.verticillioides and A. flavus toxigenic strains. The first study showed the impact of Bacillus amyloliquefaciens BA-S13, Microbacterium oleovorans DMS 16091, Enterobacter hormomaechei EM-562T, and Kluyveromyces spp. L14 and L16 isolates on mycelial growth of two strains of A. flavus MPVPA 2092, 2094 and three strains of F. verticillioides MPVPA 285, 289, and 294 on 3% maize meal extract agar at different water activities (0.99, 0.97, 0.95, and 0.93). From this first assay antagonistics isolates M. oleovorans, B. amyloliquefaciens and Kluyveromyces sp. (L16) produced an increase of lag phase of growth and decreased a growth rate of all fungal strains. These isolates were selected for futher studies. In vitro non-rhizospheric maize soil (centrally and sprayed inoculated) and in vitro maize (ears apex and base inoculated) were treated with antagonistics and pathogenic strains alone in co-inoculated cultures. Bacillus amyloliquefaciens significantly reduced F. verticillioides and A. flavus count in maize soil inoculated centrally. Kluyveromyces sp. L16 reduced F. verticillioides and A. flavus count in maize soil inoculated by spray. Kluyveromyces sp. L16 was the most effective treatment limiting percent infections by F. verticillioides on the maize ears.

Genotypic and phenotypic characterization of Cryptococcus flavescens, beneficial biocontrol agents for controlling Fusarium head blight of wheat

USDA-ARS?s Scientific Manuscript database

Cryptococcus flavescens strain OH182.9_3C (3C) previously displayed significant biological control activity against Fusarium head blight, a globally important disease of wheat; however, the diversity within C. flavescens has not been previously characterized. Multilocus sequence typing was performed...

Factors impacting the activity of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens against take-all of wheat

USDA-ARS?s Scientific Manuscript database

Take-all, caused by Gaeumannomyces graminis var. tritici, is an important soilborne disease of wheat worldwide. Pseudomonas fluorescens producing the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are biocontrol agents of take-all and provide natural suppression of the disease during wheat monocul...

Brazilian peppertree seed-borne pathogen Neofusicoccum batangarum a potential biocontrol agent

USDA-ARS?s Scientific Manuscript database

The invasive exotic Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae) has become a serious threat to the delicate ecosystem of Everglades National Park. More than 4,000 acres land in the Hole-in-the-Donut (HID) area within the Park has been infested with Brazilian pep...

Retrospective analysis of the successful establishment of a biocontrol agent based upon microsatellite data

USDA-ARS?s Scientific Manuscript database

The tarnished plant bug Lygus lineolaris is an important pest of cotton and many other crops in North America. Since the 1970s prevalence of insecticide resistant populations coupled with environmental concerns have raised interest in classical biological control of this pest. Peristenus digoneutis,...

Suitability and accessibility of immature Agrilus planipennis (Coleoptera: Buprestidae) stages to Tetrastichus planipennisi (Hymenoptera: Eulophidae)

Treesearch

Michael D. Ulyshen; Jian J. Duan; Leah S. Bauer; Ivich. Fraser

2010-01-01

Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), a gregarious larval endoparasitoid, is one of three biocontrol agents from Asia currently being released in the United States to combat the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). The current protocol for rearing T....

A paralog of the proteinaceous elicitor sm1 affects colonization of maize roots by Trichoderma virens

USDA-ARS?s Scientific Manuscript database

The biocontrol agent, Trichoderma virens, has the ability to protect plants from pathogens by eliciting plant defense responses, involvement in mycoparasitism, or secreting antagonistic secondary metabolites. SM1, an elicitor of induced systemic resistance (ISR), was found to have three paralogs wi...

Best practices for the use and exchange of invertebrate biological control genetic resources relevant for food and agriculture

USDA-ARS?s Scientific Manuscript database

Biological control is an important and environmentally preferred management option for invasive insect pests and weeds. Implementation of new international regulations governing exchange of genetic materials impacts the availability of candidate biocontrol agents, and exchange policies need to be ca...

Biology and host preferences of Cryptorhynchus melastomae (Coleoptera: Curculionidae), a possible biocontrol agent for Miconia calvescens (Melastomataceae) in Hawaii

Treesearch

E. Reichert; M.T. Johnson; E. Chacon; R.S. Anderson; T.A. Wheeler

2010-01-01

The introduced plant Miconia calvescens (Melastomataceae) poses a grave threat to Hawaii's native ecosystems and biodiversity. One potential candidate for classical biological control is Cryptorhynchus melastomae (Coleoptera: Curculionidae: Cryptorhynchinae), a stem-boring weevil from Central and South America. This weevil...

Nox Complex signal and MAPK cascade pathway are cross-linked and essential for pathogenicity and conidiation of mycoparasite Coniothyrium minitans

USDA-ARS?s Scientific Manuscript database

The NADPH oxidase complex of a sclerotial mycoparasite Coniothyrium minitans, an important biocontrol agent against crop diseases caused by Sclerotinia sclerotiorum, was identified and its functions involved in conidiation and mycoparasitism were studied. Gene knock-out and complementation experimen...

Molecular genetic and hybridization studies of Diorhabda spp. released for biological control of tamarix

USDA-ARS?s Scientific Manuscript database

The tamarisk beetle Diorhabda spp. (Coleoptera: Chrysomelidae) native to Asia and the Mediterranean Basin, is an effective biocontrol agent for use against tamarisk (Tamarix spp.) an invasive shrub in western North America. The genus Diorhabda was recently revised, using morphological characters, i...

Characterization of endophytic strains of Bacillus mojavensis and their production of surfactin isomers

USDA-ARS?s Scientific Manuscript database

Bacillus subtilis consists of a large collection of strains from which several cryptic species have been delineated, and most of these along with strains within the species are important biocontrol agents. Bacillus mojavensis, a species recently distinguished from this broad Bacillus subtilis grou...

Effects of biocontrol on short-term nutrient dynamics in a tamarix-invaded riparian ecosystem

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Saltcedar (Tamarix ramosissima) invasion and subsequent dominance in biologically and functionally diverse riparian ecosystems across the western U.S. has lead to release of the leaf beetle (Diorhabda elongata) as a biological control agent, and has resulted in large-sca...

Employing spatial information technologies to monitor biological control of saltcedar in West Texas

USDA-ARS?s Scientific Manuscript database

The saltcedar leaf beetle (Diorhadha spp.) has shown promise as a biocontrol agent for saltcedar (Tamarix spp.) invasions in the United States. In Texas, natural resource managers need assistance in monitoring biological control of invasive saltcedars. This study describes application of a medium fo...

Integrated genomic and transcriptomic analysis reveals mycoparasitism as the ancestoral life style of Trichoderma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubicek, Christian P.; Herrera-Estrella, Alfredo; Seidl, Verena

2011-04-29

Mycoparasitism, a lifestyle where one fungus is parasitic on another fungus has special relevance when the prey is a plant pathogen, providing a strategy for biological control of pests for plant protection. Probably, the most studied biocontrol agents are species of the genus Hypocrea/Trichoderma.

Pasteuria penetrans for control of Meloidogyne incognita on tomato and cucumber, and M. arenaria on snapdragon

USDA-ARS?s Scientific Manuscript database

Meloidogyne incognita and Meloidogyne arenaria, are important parasitic nematodes of vegetable and ornamental crops. Field microplot and greenhouse experiments were conducted to test commercial formulations of the biocontrol agent Pasteuria penetrans for control of M. incognita on tomato and cucumbe...

Intraguild Predation Among Biological Control Agents Used in Greenhouse Floriculture Crops: A Preliminary Review

USDA-ARS?s Scientific Manuscript database

Literature on intraguild predation (IGP) in greenhouse floriculture (GHFC) was reviewed. Despite production practices that could increase the incidence IGP, no studies concretely showed that IGP disrupts GHFC biocontrol. Further studies need to include large-scale trials over entire crop cycles. H...

Chitin Mixed in Potting Soil Alters Lettuce Growth, the Survival of Zoonotic Bacteria on the Leaves and Associated Rhizosphere Microbiology

PubMed Central

Debode, Jane; De Tender, Caroline; Soltaninejad, Saman; Van Malderghem, Cinzia; Haegeman, Annelies; Van der Linden, Inge; Cottyn, Bart; Heyndrickx, Marc; Maes, Martine

2016-01-01

Chitin is a promising soil amendment for improving soil quality, plant growth, and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia coli O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA) analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than 10-fold increase was observed for operational taxonomic units belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves. PMID:27148242

Augmenting the efficacy of antifungal intervention via chemo-biological approaches

USDA-ARS?s Scientific Manuscript database

Mycotic infection is becoming a serious health problem since effective antifungal agents for control of pathogenic fungi, especially drug-resistant pathogens, is often very limited. Fungal resistance to antimycotic agents frequently involves mutations caused by environmental stressors. In fungal pat...

Mapping the Flowering of an Invasive Plant Using Unmanned Aerial Vehicles: Is There Potential for Biocontrol Monitoring?

PubMed

de Sá, Nuno C; Castro, Paula; Carvalho, Sabrina; Marchante, Elizabete; López-Núñez, Francisco A; Marchante, Hélia

2018-01-01

Invasion by alien species is a worldwide phenomenon with negative consequences at both natural and production areas. Acacia longifolia is an invasive shrub/small tree well known for its negative ecological impacts in several places around the world. The recent introduction of a biocontrol agent ( Trichilogaster acaciaelongifoliae ), an Australian bud-galling wasp which decreases flowering of A. longifolia , in Portugal, demands the development of a cost-efficient method to monitor its establishment. We tested how unmanned aerial vehicles (UAV) can be used to map A. longifolia flowering. Our core assumption is as the population of the biocontrol agent increases, its impacts on the reduction of A. longifolia flowering will be increasingly visible. Additionally, we tested if there is a simple linear correlation between the number of flowers of A. longifolia counted in field and the area covered by flowers in the UAV imagery. UAV imagery was acquired over seven coastal areas including frontal dunes, interior sand dunes and pine forests considering two phenological stages: peak and off-peak flowering season. The number of flowers of A. longifolia was counted, in a minimum of 60 1 m 2 quadrats per study area. For each study area, flower presence/absence maps were obtained using supervised Random Forest. The correlation between the number of flowers and the area covered by flowering plants could then be tested. The flowering of A. longifolia was mapped using UAV mounted with RGB and CIR Cannon IXUS/ELPH cameras (Overall Accuracy > 0.96; Cohen's Kappa > 0.85) varying according to habitat type and flowering season. The correlation between the number of flowers counted and the area covered by flowering was weak ( r 2 between 0.0134 and 0.156). This is probably explained, at least partially, by the high variability of A. longifolia in what regards flowering morphology and distribution. The very high accuracy of our approach to map A. longifolia flowering proved to be cost efficient and replicable, showing great potential for detecting the future decrease in flowering promoted by the biocontrol agent. The attempt to provide a low-cost method to estimate A. longifolia flower productivity using UAV failed, but it provided valuable insights on the future steps.

A constitutively expressed antifungal peptide protects Tenebrio molitor during a natural infection by the entomopathogenic fungus Beauveria bassiana.

PubMed

Maistrou, Sevasti; Paris, Véronique; Jensen, Annette B; Rolff, Jens; Meyling, Nicolai V; Zanchi, Caroline

2018-09-01

Antimicrobial peptides have been well studied in the context of bacterial infections. Antifungal peptides have received comparatively less attention. Fungal pathogens of insects and their hosts represent a unique opportunity to study host-pathogen interactions due to the million of years of co-evolution they share. In this study, we investigated role of a constitutively expressed thaumatin-like peptide with antifungal activity expressed by the mealworm beetle Tenebrio molitor, named Tenecin 3, during a natural infection with the entomopathogenic fungus Beauveria bassiana. We monitored the effect of the expression of Tenecin 3 on the survival of infected hosts as well as on the progression of the fungal infection inside the host. Finally, we tested the activity of Tenecin 3 against B. bassiana. These findings could help improving biocontrol strategies and help understanding the evolution of antifungal peptides as a defense mechanism. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of Some Pesticides on the Growth of ARF18 and Its Pathogenicity to Heterodera glycines

PubMed Central

Kim, D. G.; Riggs, R. D.

1998-01-01

The effects of 22 pesticides on the mycelial growth and pathogenicity of the biocontrol fungus ARFI8 to Heterodera glycines were tested in vitro. The chemicals were added to agar at 10, 100, and 1,000 ppm a.i.; a block of agar containing the fungus was added to each test concentration; and fungal growth was measured. Subsequently, a block of the fungus on the pesticide-containing agar was used to determine the ability of the fungus to parasitize eggs of H. glycines. Aldicarb, bentazone, and chlorothalonil had little or no effect on fungal growth, whereas benomyl and thiophanate methyl completely inhibited growth of the fungus at 10 ppm. The relative insensitivity of ARF18 to certain pesticides would permit selected use of those pesticides with ARF18 in an integrated control program if the effects on the fungus in the field are similar to results from petri dish studies. PMID:19274211

Relationship between mycoparasites lifestyles and biocontrol behaviors against Fusarium spp. and mycotoxins production.

PubMed

Kim, Seon Hwa; Vujanovic, Vladimir

2016-06-01

Global food security research is seeking eco-friendly solutions to control mycotoxins in grain infected by fungi (molds). In particular, mycotoxigenic Fusarium spp. outbreak is a chronic threat for cereal grain production, human, and animal health. In this review paper, we discuss up-to-date biological control strategies in applying mycoparasites as biological control agents (BCA) to prevent plant diseases in crops and mycotoxins in grain, food, and feed. The aim is to increase food safety and to minimize economic losses due to the reduced grain yield and quality. However, recent papers indicate that the study of the BCA specialists with biotrophic lifestyle lags behind our understanding of the BCA generalists with necrotrophic lifestyle. We examine critical behavioral traits of the two BCA groups of mycoparasites. The goal is to highlight their major characteristics in the context of future research towards an efficient biocontrol strategy against mycotoxin-producing Fusarium species. The emphasis is put on biocontrol of Fusarium graminearum, F. avenaceum, and F. culmorum causing Fusarium head blight (FHB) in cereals and their mycotoxins.

Comparative genomic analysis of novel bacteriophages infecting Vibrio parahaemolyticus isolated from western and southern coastal areas of Korea.

PubMed

Yu, Junhyeok; Lim, Jeong-A; Kwak, Su-Jin; Park, Jong-Hyun; Chang, Hyun-Joo

2018-05-01

Vibrio parahaemolyticus, a foodborne pathogen, has become resistant to antibiotics. Therefore, alternative bio-control agents such bacteriophage are urgently needed for its control. Six novel bacteriophages specific to V. parahaemolyticus (vB_VpaP_KF1~2, vB_VpaS_KF3~6) were characterized at the molecular level in this study. Genomic similarity analysis revealed that these six bacteriophages could be divided into two groups with different genomic features, phylogenetic grouping, and morphologies. Two groups of bacteriophages had their own genes with different mechanisms for infection, assembly, and metabolism. Our results could be used as a future reference to study phage genomics or apply phages in future bio-control studies.

Enhancement of commercial antifungal agents by kojic acid

USDA-ARS?s Scientific Manuscript database

Kojic acid (KA), a natural by-product of fungal fermentation, is a commonly used food and cosmetic additive. We show that KA increases activity of amphotericin B and strobilurin, medical and agricultural antifungal agents, respectively, possibly targeting the fungal antioxidative system. KA shows pr...

Growth of chitinolytic dune soil beta-subclass Proteobacteria in response to invading fungal hyphae.

PubMed

De Boer, W; Klein Gunnewiek, P J; Kowalchuk, G A; Van Veen, J A

2001-08-01

It has frequently been reported that chitinolytic soil bacteria, in particular biocontrol strains, can lyse living fungal hyphae, thereby releasing potential growth substrate. However, the conditions used in such assays (high bacterial density, rich media, fragmented hyphae) make it difficult to determine whether mycolytic activity is actually of importance for the growth and survival of chitinolytic bacteria in soils. An unidentified group of beta-subclass Proteobacteria (CbetaPs) was most dominant among the culturable nonfilamentous chitinolytic bacteria isolated from Dutch sand dune soils. Here we demonstrate that the CbetaPs grew at the expense of extending fungal mycelium of three dune soil fungi (Chaetomium globosum, Fusarium culmorum, and Mucor hiemalis) under nutrient-limiting, soil-like conditions. Aggregates of CbetaPs were also often found attached to fungal hyphae. The growth of a control group of dominant nonchitinolytic dune soil bacteria (beta- and gamma-subclass Proteobacteria) was not stimulated in the mycelial zone, indicating that growth-supporting materials were not independently released in appreciable amounts by the extending hyphae. Therefore, mycolytic activities of CbetaPs have apparently been involved in allowing them to grow after exposure to living hyphae. The chitinase inhibitor allosamidin did not, in the case of Mucor, or only partially, in the cases of Chaetomium and Fusarium, repress mycolytic growth of the CbetaPs, indicating that chitinase activity alone could not explain the extent of bacterial proliferation. Chitinolytic Stenotrophomonas-like and Cytophaga-like bacteria, isolated from the same dune soils, were only slightly stimulated by exposure to fungal hyphae.

Whole-Genome Sequence of Pseudomonas fluorescens EK007-RG4, a Promising Biocontrol Agent against a Broad Range of Bacteria, Including the Fire Blight Bacterium Erwinia amylovora.

PubMed

Habibi, Roghayeh; Tarighi, Saeed; Behravan, Javad; Taheri, Parissa; Kjøller, Annelise Helene; Brejnrod, Asker; Madsen, Jonas Stenløkke; Sørensen, Søren Johannes

2017-03-30

Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora , the causal agent for fire blight disease, in addition to several other pathogenic and non-pathogenic bacteria. Copyright © 2017 Habibi et al.

Different strategies to kill the host presented by Metarhizium anisopliae and Beauveria bassiana.

PubMed

Rustiguel, Cynthia Barbosa; Fernández-Bravo, María; Guimarães, Luis Henrique Souza; Quesada-Moraga, Enrique

2018-03-01

Studies conducted over the last decades have shown the potential of entomopathogenic fungi for the biocontrol of some insect pests. Entomopathogenic fungi infect their host through the cuticle, so they do not need to be ingested to be effective. These fungi also secrete secondary metabolites and proteins that are toxic to insect pests. In this context, we analyzed the pathogenicity of Metarhizium anisopliae (Metschn.) strains IBCB 384 and IBCB 425 and Beauveria bassiana (Bals.-Criv.) Vuill. strains E 1764 and E 3158 against Galleria mellonella (Linn.) larvae, during pre-invasion and post-invasion phases. The results showed M. anisopliae, especially strain IBCB 384, was most virulent in the pre-invasion phase against G. mellonella, whereas B. bassiana, especially strain E 1764, was most virulent in the post-invasion phase. During in vivo development and in the production of toxic serum, B. bassiana E 3158 was the most virulent. Different fungal growth (or toxin) strategies were observed for studied strains. Metarhizium anisopliae IBCB 425 prioritizes the growth strategy, whereas strain IBCB 384 and B. bassiana strains E 1764 and E 3158 have a toxic strategy. All strains have pathogenicity against G. mellonella, indicating their possible use for biocontrol.

Two-photon microscopy of fungal keratitis-affected rabbit cornea ex vivo using moxifloxacin as a labeling agent.

PubMed

Lee, Jun Ho; Le, Viet-Hoan; Lee, Seunghun; Park, Jin Hyoung; Lee, Jin Ah; Tchah, Hungwon; Kim, Sungjee; Kim, Myoung Joon; Kim, Ki Hean

2018-05-19

Two-photon microscopy (TPM) is a three dimensional (3D) microscopic technique based on nonlinear two-photon fluorescence, which has been tested as an alternative to reflectance confocal microscopy (RCM) for detecting fungal keratitis via optical imaging. Although TPM provided images with better contrast than RCM for fungal keratitis, its imaging speed was relatively low because of weak intrinsic signal. Moxifloxacin, a Food and Drug Administration (FDA)-approved antibiotic, was recently used as a cell-labeling agent for TPM. In this study, moxifloxacin was used to label fungal cells for TPM imaging of fungal keratitis models. Fungal cell suspensions and ex vivo fungal keratitis-affected rabbit corneas were prepared using two types of fungal pathogens, Aspergillus fumigatus and Candida albicans, and TPM imaging was performed both with and without moxifloxacin treatment. Fungal cells with enhanced fluorescence were clearly visible by TPM of moxifloxacin-treated fungal cell suspensions. TPM of moxifloxacin-treated fungal keratitis rabbit corneas revealed both the infecting fungal cells and corneal cells similar to those observed in TPM without moxifloxacin treatment, albeit with approximately 10-times enhanced fluorescence. Fungal cells were distinguished from corneal cells on the basis of their distinct morphologies. Thus, TPM with moxifloxacin labeling might be useful for the detection of fungal keratitis at the improved imaging speed. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Variable Demographic Rates in an Invasive Plant Species: Differences Among Populations and Management Implications

USDA-ARS?s Scientific Manuscript database

Population managers are frequently faced with the challenge of selecting the most effective management strategy from a set of available strategies. In the case of classical weed biological control, this requires predicting a priori which of a group of candidate biocontrol agent species has the great...

USDA Cranberry Entomology Laboratory (CEL) research priorities in the 2016 growing season

USDA-ARS?s Scientific Manuscript database

Research priorities during the 2016 growing season will be focused on 1) discovery and screening of native WI nematodes as bio-control agents, and 2) continued refinement of the drone-deployed mating disruption system. Extramural funding will be needed for both, and the degree of funding will dictat...

Life cycle and control of the cyst nematode Heterodera goldeni on rice in Egypt

USDA-ARS?s Scientific Manuscript database

The life cycle and methods for control of the cyst nematode Heterodera goldeni on rice (Oryza sativa) were examined in the greenhouse. Three tests were conducted to study the effects of soil treatments with some plant materials, stems of oyster mushroom (Pleurotus ostreatus), the biocontrol agent Ba...

Field garden experiments to assess the host specificity of Aceria solstitialis (Acari: Eriophyoidea), potential biocontrol agent for Centaurea solstitialis (Asteraceae)

USDA-ARS?s Scientific Manuscript database

Centaurea solstitialis (yellow starthistle) is an annual noxious weed that currently infests millions of acres of rangelands, non-cultivated and natural areas in the Western USA. It displaces native plant communities reducing plant diversity and forage production for livestock and wildlife. Aceria s...

The large decapitating fly Pseudacteon litoralis (Diptera: Phoridae): Successfully established on fire ant populations in Alabama

USDA-ARS?s Scientific Manuscript database

The large fire ant decapitating fly, Pseudacteon litoralis Borgmeier from northeastern Argentina was successfully released as a self-sustaining biocontrol agent of imported fire ants in south central Alabama in 2005. Five years later, this fly is firmly established at this site and has expanded out...

Development of microsatellite markers for Peristenus digoneutis (Hymenoptera: Braconidae), an important natural enemy of tarnished plant bugs

USDA-ARS?s Scientific Manuscript database

The introduced European parasitoid Peristenus digoneutis is an important biocontrol agent of lygus bug pests in agricultural crops in the Northeastern USA. Changes in cultural practices and reduction of alfalfa culture in its native range has significantly reduced its distribution compared to its hi...

Predator in First: A prophylactic biological control strategy for management of multiple pests of pepper

USDA-ARS?s Scientific Manuscript database

The establishment of biocontrol agents is critical for success of biological control strategies. Predator-In-First (PIF) is a prophylactic control strategy that aims to establish predators before the appearance of pests in an agro-ecosystem. Predator-In-First uses the characteristics of generalist p...

Evaluation of the atoxigenic Aspergillus flavus strain AF36 in pistachio orchards

USDA-ARS?s Scientific Manuscript database

The atoxigenic strain Aspergillus flavus AF36, which has been extensively used as a biocontrol agent in commercial corn and cotton fields to reduce aflatoxin contamination, was applied in research pistachio orchards from 2002 to 2005 and in commercial pistachio orchards from 2008 to 2011. AF36 was a...

Invasion genetics of emerald ash borer in North America

Treesearch

Alicia M. Bray; Leah S. Bauer; Robert A. Haack; Therese Poland; James J. Smith

2006-01-01

Emerald ash borer (EAB) was first detected in Michigan and Canada in 2002. Efforts to eradicate this destructive pest by federal and state regulatory agencies continue. Knowledge of EAB genetics will be useful in understanding the invasion dynamics of the beetle and to help identify geographic localities of potential biocontrol agents.

Suitability and Accessibility of Immature Agrilus planipennis (Coleoptera: Buprestidae) Stages to Tetrastichus planipennisi (Hymenoptera: Eulophidae).

Treesearch

Michael Ulyshen; Jian Duan; Leah Bauer; Ivich Fraser

2010-01-01

Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), a gregarious larval endoparasitoid, is one of three biocontrol agents from Asia currently being released in the United States to combat the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). The current protocol for rearing T. planipennisi involves presenting the wasps with...

Ability of secondary metabolites from trichoderma virens to mediate communication during mutualistic or pathogenic interactions

USDA-ARS?s Scientific Manuscript database

A bioinformatic study was conducted to identify the putative genes in the biocontrol agent Trichoderma virens that encode for non-ribosomal peptide synthetases (NRPS). Gene expression analysis of 22 putative NRPSs and 4 NRPS/PKS (polyketide synthase) hybrid enzymes was conducted in the presence and...

In vitro testing of biological control agents on A1 and A2 isolates of Phytophthora ramorum

Treesearch

Marianne Elliott; Simon Shamoun

2008-01-01

Biological control products were tested in vitro with six isolates of Phytophthora ramorum. These isolates were geographically diverse and were selected based on their pathogenicity to detached Rhododendron leaves. In addition to five commercially available biocontrol products, nine species of Trichoderma were tested. The in vitro...

Development and characterization of 11 microsatellite markers in the root-gall-forming weevil, Ceutorhynchus assimilis (Coleoptera: Curculionidae)

USDA-ARS?s Scientific Manuscript database

The host race of Ceutorhynchus assimilis (Coleoptera: Curculionidae) that specifically develops on Lepidium draba (Brassicales: Brassicaceae), an invasive weed in North America, is being considered for use as a biocontrol agent. Because there are other races that attack other plants, it is important...

Efficacy of bacillus biocontrol agents for management of sheath blight and narrow brown leaf spot in organic rice

USDA-ARS?s Scientific Manuscript database

Organic rice production has significantly increased in the U. S. over the last decade. Growers lack effective tools to manage sheath blight, caused by Rhizoctonia solani, and narrow brown leaf spot (NBLS), caused by Cercospora janseana, two major diseases affecting organic rice production. An experi...

Influence of temperature on the reproductive and developmental biology of Ontsira mellipes (Hymenoptera: Braconidae): Implications for biological control of the Asian Longhorned Beetle (Coleoptera: Cerambycidae)

USDA-ARS?s Scientific Manuscript database

Ontsira mellipes Ashmead (Hymenoptera: Braconidae) is a North American parasitoid that develops on the invasive pest, Anoplophora glabripennis (Moltschulsky) (Coleoptera: Cerambycidae) under laboratory conditions, and is currently being considered as a potential new-association biocontrol agent. In ...

Changes in expression of oxidative stress related genes in grapefruit peel in response to yeast Metschnikowia fructicola

USDA-ARS?s Scientific Manuscript database

To gain insight into the mode of action of the yeast biocontrol agent, Metschnikowia fructicola, the transcription profiles of genes involved in oxidative stress were studied in grapefruit (Citrus paradis, 'Star Ruby') surface wounds following the application of the yeast antagonist. Three transcri...

The combined approach of strain discovery and the inbred line technique for improving control of Delia radicum with Heterorhabditis bacteriophora

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes are potent biocontrol agents but their efficacy can be compromised under unfavorable environmental conditions such as cold temperatures. Discovery of new nematode species or strains that are adapted to local conditions is one approach that can be used to enhance efficacy. ...

"Is post hoc development of risk management in weed biocontrol too late? Lessons learned from Cactoblastis cactorum"

USDA-ARS?s Scientific Manuscript database

Cactoblastis cactorum is renowned for its success as a biological control agent against exotic Opuntia spp. in many locations including Australia, South Africa and Hawaii. However, in 1957, its introduction into the Caribbean to control native Opuntia spp. ultimately resulted in its arrival to sout...

Is post hoc development of risk management in weed biocontrol too late? Lessons learned from Cactoblastis cactorum.

USDA-ARS?s Scientific Manuscript database

Cactoblastis cactorum is renowned for its success as a biological control agent against exotic Opuntia spp. in many locations including Australia, South Africa and Hawaii. However, in 1957, its introduction into the Caribbean to control native Opuntia spp. ultimately resulted in its arrival to sout...

Biological control of ticks

USGS Publications Warehouse

Samish, M.; Ginsberg, H.; Glazer, I.; Bowman, A.S.; Nuttall, P.

2004-01-01

Ticks have numerous natural enemies, but only a few species have been evaluated as tick biocontrol agents (BCAs). Some laboratory results suggest that several bacteria are pathogenic to ticks, but their mode of action and their potential value as biocontrol agents remain to be determined. The most promising entomopathogenic fungi appear to be Metarhizium anisopliae and Beauveria bassiana, strains of which are already commercially available for the control of some pests. Development of effective formulations is critical for tick management. Entomopathogenic nematodes that are pathogenic to ticks can potentially control ticks, but improved formulations and selection of novel nematode strains are needed. Parasitoid wasps of the genus Ixodiphagus do not typically control ticks under natural conditions, but inundative releases show potential value. Most predators of ticks are generalists, with a limited potential for tick management (one possible exception is oxpeckers in Africa). Biological control is likely to play a substantial role in future IPM programmes for ticks because of the diversity of taxa that show high potential as tick BCAs. Considerable research is required to select appropriate strains, develop them as BCAs, establish their effectiveness, and devise production strategies to bring them to practical use.

Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products

PubMed Central

Sváb, Domonkos; Falgenhauer, Linda; Rohde, Manfred; Szabó, Judit; Chakraborty, Trinad; Tóth, István

2018-01-01

During recent years, interest in the use of bacteriophages as biocontrol agents against foodborne pathogens has increased, particularly for members of the family Enterobacteriaceae, with pathogenic Escherichia coli, Shigella, and Salmonella strains among them. Here, we report the isolation and characterisation of 12 novel T5-like bacteriophages from confiscated food samples. All bacterophages effectively lysed E. coli K-12 strains and were able to infect pathogenic E. coli strains representing enterohaemorrhagic (EHEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), and enteroinvasive (EIEC) pathotypes, Shigella dysenteriae, S. sonnei strains, as well as multidrug-resistant (MDR) E. coli and multiple strains representing different Salmonella enterica serovars. All the bacteriophages exhibited Siphoviridae morphology. Whole genome sequencing of the novel T5-like bacteriophages showed that they represent two distinct groups, with the genome-based grouping correlating to the different host spectra. As these bacteriophages are of food origin, their stability and lack of any virulence genes, as well as their broad and mutually complementary host spectrum makes these new T5-like bacteriophages valuable candidates for use as biocontrol agents against foodborne pathogenic enterobacteria. PMID:29487585

Production and characterization of rhamnolipids produced by Serratia rubidaea SNAU02 under solid-state fermentation and its application as biocontrol agent.

PubMed

Nalini, S; Parthasarathi, R

2014-12-01

The present study aimed at exploring mahua (Madhuca indica) oil cake as a novel substrate for the production of biosurfactant by Serratia rubidaea SNAU02 under solid-state fermentation (SSF). Response surface methodology showed followings as the optimal conditions for the production of biosurfactant: mahua oil cake 7.48 g, 2.5 ml inoculum size (1×10(8) cells/ml), and pH 7.22 and 31 °C temperature. The characterization of the biosurfactant by TLC, FT-IR and GC-MS revealed the presence of rhamnolipid. The presence of rhamnosyl transferase gene responsible for biosynthesis of rhamnolipid was identified. The strain SNAU02 exhibited antifungal activity and demonstrated no toxicity against the seeds of Brassica oleracea and Artemia salina employed as a bio-indicator. The present findings indicated the potential of mahua oil cake as suitable substrate for the production of rhamnolipids in SSF by S. rubidaea SNAU02 and application potential of the biosurfactant produced as biocontrol agent against plant pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Complete genome sequence of new bacteriophage phiE142, which causes simultaneously lysis of multidrug-resistant Escherichia coli O157:H7 and Salmonella enterica.

PubMed

Amarillas, Luis; Chaidez, Cristobal; González-Robles, Arturo; León-Félix, Josefina

2016-01-01

The emergence of antibiotic-resistant foodborne bacteria is a global health problem that requires immediate attention. Bacteriophages are a promising biotechnological alternative approach against bacterial pathogens. However, a detailed analysis of phage genomes is essential to assess the safety of the phages prior to their use as biocontrol agents. Therefore, here we report the complete genome sequence of bacteriophage phiE142, which is able to lyse Salmonella and multidrug-resistant Escherichia coli O157:H7 strains. Bacteriophage phiE142 belongs to the Myoviridae family due to the presence of long non-flexible tail and icosahedral head. The genome is composed of 121,442 bp and contains 194 ORFs, and 2 tRNAs. Furthermore, the phiE142 genome does not contain any genes coding for food-borne allergens, antibiotics resistance, virulence factors, or associated with lysogenic conversion. The bacteriophage phiE142 is characterized by broad host range and compelling genetic attributes making them potential candidates as a biocontrol agent.

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

PubMed Central

Gharamah, Abdullah A; Moharram, Ahmed M; Ismail, Mady A; AL-Hussaini, Ashraf K

2014-01-01

Purpose: This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents. Materials and Methods: One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested. Results: Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro. Conclusion: In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss. PMID:24008795

Novel Routes for Improving Biocontrol Activity of Bacillus Based Bioinoculants

PubMed Central

Wu, Liming; Wu, Hui-Jun; Qiao, Junqing; Gao, Xuewen; Borriss, Rainer

2015-01-01

Biocontrol (BC) formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of BC agents. PMID:26696998

Augmentative Biocontrol in Natural Marine Habitats: Persistence, Spread and Non-Target Effects of the Sea Urchin Evechinus chloroticus

PubMed Central

Atalah, Javier; Hopkins, Grant A.; Forrest, Barrie M.

2013-01-01

Augmentative biocontrol aims to control established pest populations through enhancement of their indigenous enemies. To our knowledge, this approach has not been applied at an operational scale in natural marine habitats, in part because of the perceived risk of adverse non-target effects on native ecosystems. In this paper, we focus on the persistence, spread and non-target effects of the sea urchin Evechinus chloroticus when used as biocontrol agent to eradicate an invasive kelp from Fiordland, New Zealand. Rocky reef macrobenthic assemblages were monitored over 17 months in areas where the indigenous algal canopy was either removed or left intact prior to the translocation of a large number of urchins (>50 ind.·m−2). Urchin densities in treated areas significantly declined ∼9 months after transplant, and began spreading to adjacent sites. At the end of the 17-month study, densities had declined to ∼5 ind.·m−2. Compared to controls, treatment sites showed persistent shifts from kelp forest to urchin barrens, which were accompanied by significant reductions in taxa richness. Although these non-target effects were pronounced, they were considered to be localised and reversible, and arguably outweigh the irreversible and more profound ecological impacts associated with the establishment of an invasive species in a region of high conservation value. Augmentative biocontrol, used in conjunction with traditional control methods, represents a promising tool for the integrated management of marine pests. PMID:24260376

Pretreatment of the yeast antagonist, Candida oleophila with glycine betaine increases oxidative stress tolerance in the microenvironment of apple wounds

USDA-ARS?s Scientific Manuscript database

In response to wounding, harvested fruit tissues of apple and citrus exhibit the production of reactive oxygen species (ROS). ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. These phenomena result in an oxidative stress environment for the yeas...

First record of Acizzia jamatonica (Hemiptera: Psyllidae) in North America: friend or foe?

Treesearch

Michael D. Ulyshen; Douglass Miller

2007-01-01

Acizzia jamatonica (Kuwayama) (Hemiptera: Sternorrhyncha: Psyllidae) is reported for the first time in North America. Because the species is thought to feed exclusively on Albizia, it may prove to be an effective biocontrol agent against the invasive Albizia julibrissin Durazzini in the southeastern United States. Because A. julibrissin is also an ornamental plant of...

Field-cage methodology for evaluating climatic suitability for introduced wood-borer parasitoids: preliminary results from the emerald ash borer system

Treesearch

Michael D. Ulyshen; Jian J. Duan; Leah S. Bauer; Juli Gould; Phil Taylor; Dick Bean; Carol Holko; Roy Van Driesche

2011-01-01

Field-cage methods were developed to evaluate the abilities of Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius agrili Yang (Hymenoptera: Braconidae), biocontrol agents of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), to parasitize, develop and overwinter following three late-season releases at both a northern (Michigan) and a southern (...