scholarly journals Evaluation of in-vitro methods to select effective streptomycetes against toxigenic fusaria

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6905 ◽  
Author(s):  
Elena Maria Colombo ◽  
Cristina Pizzatti ◽  
Andrea Kunova ◽  
Claudio Gardana ◽  
Marco Saracchi ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Culture Media ◽  
Screening Methods ◽  
Dual Culture ◽  
In Planta ◽  
In Vitro Method ◽  
In Vitro Methods ◽  
Strain Diversity ◽  
Fungal Plant Pathogens

Biocontrol microorganisms are emerging as an effective alternative to pesticides. Ideally, biocontrol agents (BCAs) for the control of fungal plant pathogens should be selected by an in vitro method that is high-throughput and is predictive of in planta efficacy, possibly considering environmental factors, and the natural diversity of the pathogen. The purpose of our study was (1) to assess the effects ofFusariumstrain diversity (N= 5) and culture media (N= 6) on the identification of biological control activity ofStreptomycesstrains (N= 20) againstFusariumpathogens of wheat in vitro and (2) to verify the ability of our in vitro screening methods to simulate the activity in planta. Our results indicate that culture media,Fusariumstrain diversity, and their interactions affect the results of an in vitro selection by dual culture assay. The results obtained on the wheat-based culture media resulted in the highest correlation score (r= 0.5) with the in planta root rot (RR) inhibition, suggesting that this in vitro method was the best predictor of in planta performance of streptomycetes against Fusarium RR of wheat assessed as extension of the necrosis on the root. Contrarily, none of the in vitro plate assays using the media tested could appropriately predict the activity of the streptomycetes against Fusarium foot rot symptoms estimated as the necrosis at the crown level. Considering overall data of correlation, the activity in planta cannot be effectively predicted by dual culture plate studies, therefore improved in vitro methods are needed to better mimic the activity of biocontrol strains in natural conditions. This work contributes to setting up laboratory standards for preliminary screening assays ofStreptomycesBCAs against fungal pathogens.

scholarly journals Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Yan Ramona ◽  
IDA BAGUS GEDE DARMAYASA ◽  
ANAK AGUNG NGURAH NARA KUSUMA ◽  
Martin Line
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Antagonistic Activity ◽  
Significant Inhibition ◽  
Biocontrol Agents ◽  
Dual Culture ◽  
Rdna Sequences ◽  
Fungal Plant Pathogens ◽  
Mature Compost

Abstract. Ramona Y, Darmayasa IBG, Kusuma AANN, Line MA. 2021. Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens. Biodiversitas 22: 298-303. This study investigated the inhibitory potential of diversity of antagonist bacteria residing in the rhizosphere zone and mature compost to counter fungal plant pathogens. Soils collected from rhizosphere of lettuce farms in Bali-Indonesia and Tasmania-Australia, mature compost, commercial biocontrol (Dipel®), and laboratory contaminants with significant inhibition against tested fungal pathogens were used as sources of antagonist bacteria. These antagonists were isolated by applying dilution and spread method on trypticase soya agar (TSA) or potato dextrose agar (PDA), and their ability to inhibit Sclerotinia minor, Sclerotinia sclerotiorum, Fusarium spp., and Rhizoctonia solani was assessed in dual culture assays. The results showed that 67 out of more than 100 isolates had antagonistic activity in vitro against at least one of tested fungal pathogens. In the preliminary identification, Bacillus spp. or Pseudomonas spp. were found to be pre-dominant isolates. Following screening studies in a non-replicated glasshouse experiment against S. minor and S. sclerotiorum, 8 of the most promising isolates were further identified using molecular methods based on their 16s rDNA sequences aligned with those deposited at the GeneBank. These 8 isolates were identified as Pseudomonas corrugata, Bacillus megaterium, Bacillus polymyxa, Bacillus mojavensis, Bacillus pumilus, Bacillus thuringiensis, Exiguobacterium acetylicum, and Chryseobacterium indologenes.

scholarly journals In-vitro Evaluation of Actinobacteria for its Potential in Bio-control of Fungal Plant Pathogens

2019 ◽  
Vol 7 (1) ◽  
pp. 82-87
Author(s):  
Zothan puia ◽  
◽  
W. Carrie ◽  
V.V. Leo ◽  
A.K. Passari ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Control Strategies ◽  
Dual Culture ◽  
Inhibition Activity ◽  
Fungal Plant Pathogens ◽  
Basic Understanding ◽  
Dual Culture Assay ◽  
Antagonistic Potential ◽  
Fungal Phytopathogens

Infections caused by fungal plant pathogens are recently recognized as a threat to food security worldwide and its control strategies need to be taken care where naturally synthesized fungicides such as those obtained from actinobacteria are becoming an area of great interest. A total of 68 isolates of actinobacteria were evaluated for their antagonistic potential against four fungal plant pathogens viz., Fusarium oxysporum CABI-293942, Fusarium udum MTCC-2755, Fusarium proliferatum MTCC-286 and Fusarium graminearum MTCC-1893 by dual culture assay. It was found that 83.8% of the isolates showed inhibitory activity against at least one of the tested plant pathogens with the percentage of inhibition ranging from 20–87.2. Thirteen Streptomyces isolates and one Nocardiposis isolate exhibited inhibition activity against all the tested pathogens. Overall, this study gives a basic understanding of the potential aspect of freshwater sediments derived actinobacteria against fungal phytopathogens.

scholarly journals PHIALOMYCES MACROSPORUS REDUCES CERCOSPORA COFFEICOLA SURVIVAL ON SYMPTOMATIC COFFEE LEAVES

2019 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Marie Caroline Ferreira Laborde ◽  
Deila Magna dos Santos Botelho ◽  
Gabriel Alfonso Alvarez Rodriguez ◽  
Mário Lúcio Vilela de Resende ◽  
Marisa Vieira de Queiroz ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Disease Rate ◽  
In Planta ◽  
Necrotrophic Pathogen ◽  
Initial Inoculum ◽  
Saprobe Fungi ◽  
Cercospora Coffeicola ◽  
Brown Eye Spot

<p>Saprobe fungi and necrotrophic pathogens share the same niche within crop stubble and the search for fungi non-pathogenic to plants that are able to displace the plant pathogens from its overwintering substrate contributes to the disease management. Brown eye spot (<em>Cercospora coffeicola</em>) is among the most important coffee diseases, it is caused by a necrotrophic pathogen that has decaying leaves as its major source of inoculum. We have screened saprobe fungi for the ability to reduce <em>C. coffeicola</em> sporulation and viability and determined the possible mechanisms involved in the observed biocontrol. A selected saprobe fungus, <em>Phialomyces macrosporus</em>, reduced the pathogen’s viability by 40% both <em>in vitro</em> and <em>in vivo</em>. The fungus acts through antibiosis and competition for nutrients. It produced both volatile and non-volatile compounds that inhibited <em>C. coffeicola</em> growth, sporulation, and viability. It also produced the tissue maceration enzyme (polygalacturonase), which reduces the pathogen both in detached leaves or in planta. The reduction in the fungal viability either by the saprobe fungus or its polygalacturonase-fraction supernatant resulted in the reduction of the disease rate. Therefore, <em>P. macrosporus </em>is a potential microbial agent that can be used in an integrated management of brown eye spot through the reduction of the initial inoculum of the pathogen that survives and builds up in infected leaves.</p><p> </p>

scholarly journals Inhibitory Effect of Trichoderma asperellum Isolate against Ralstonia solanacearum Causing Brinjal Wilt

2021 ◽  
Vol 24 (2) ◽  
pp. 107-120
Author(s):  
SMN Islam ◽  
SS Siddique ◽  
MZH Chowdhury ◽  
NJ Mishu
Keyword(s):  
Ralstonia Solanacearum ◽  
Disease Incidence ◽  
Its Region ◽  
Inhibitory Effect ◽  
Dual Culture ◽  
Trichoderma Asperellum ◽  
In Planta ◽  
Quantitative Test ◽  
Trichoderma Isolate

A native Trichoderma isolate was collected from the agricultural soil of Gazipur. This isolate was identified as a Trichoderma asperellum through morphology and analysis of internal transcribed spacer (ITS) region of ribosomal RNA gene sequence and reconstruction of the phylogenetic tree. The antagonistic effects of the newly identified T. asperellum isolate were assessed against brinjal bacterial wilt caused by Ralstonia solanacearum both in vitro and in planta. Both qualitative and quantitative bioassays were conducted in vitro. For qualitative tests, dual culture and antibacterial activity were carried out, and pathogen growth was observed visually. The antagonism of T. asperellum cell free culture filtrate on the growth of R. solanacearum was conducted in a quantitative test. Successful antagonism was recorded after both in vitro qualitative tests. In addition, the lowest colony forming unit was recorded in 100% of CFC (2.4±0.51 ×103 cfu/ml) in quantitative test. The T. asperellum inoculated plant showed low disease incidence (13.33%) when seedlings were challenged with R. solanacearum in planta experiment. Disease incidence was 100% for seedlings when treated with only R. solanacearum. The results showed that the isolated and identified T. asperellum isolate suppressed R. solanacearum growth in vitro and protected the seedling from wilting in planta. Therefore, this isolate could be considered as a potential isolate. Ann. Bangladesh Agric. (2020) 24(2) : 107-120

scholarly journals Plant Defensin Peptides have Antifungal and Antibacterial Activity Against Human and Plant Pathogens

2019 ◽  
Vol 109 (3) ◽  
pp. 402-408 ◽  
Author(s):  
Andrew E. Sathoff ◽  
Siva Velivelli ◽  
Dilip M. Shah ◽  
Deborah A. Samac
Keyword(s):  
Antibacterial Activity ◽  
Plant Pathogens ◽  
Crown Rot ◽  
Plant Defensin ◽  
Core Motif ◽  
Potential Control ◽  
Fungal Plant Pathogens ◽  
Plant Defensins ◽  
Animal Pathogens

Plant defensins are small, cysteine-rich antimicrobial peptides. These peptides have previously been shown to primarily inhibit the growth of fungal plant pathogens. Plant defensins have a γ-core motif, defined as GXCX3-9C, which is required for their antifungal activity. To evaluate plant defensins as a potential control for a problematic agricultural disease (alfalfa crown rot), short, chemically synthesized peptides containing γ-core motif sequences were screened for activity against numerous crown rot pathogens. These peptides showed both antifungal and, surprisingly, antibacterial activity. Core motif peptides from Medicago truncatula defensins (MtDef4 and MtDef5) displayed high activity against both plant and human bacterial pathogens in vitro. Full-length defensins had higher antimicrobial activity compared with the peptides containing their predictive γ-core motifs. These results show the future promise for controlling a wide array of economically important fungal and bacterial plant pathogens through the transgenic expression of a plant defensin. They also suggest that plant defensins may be an untapped reservoir for development of therapeutic compounds for combating human and animal pathogens.

scholarly journals In-vitro Evaluation of Bio-control agents against Soil Borne Plant Pathogens

2019 ◽  
Vol 5 ◽  
pp. 68-72
Author(s):  
Shrinkhala Manandhar ◽  
Bimala Pant ◽  
Chetana Manandhar ◽  
Suraj Baidya
Keyword(s):  
Plant Pathogens ◽  
Field Experiments ◽  
Colony Growth ◽  
Dual Culture ◽  
Vitro Assay ◽  
Trichoderma Species ◽  
Soil Borne Pathogens ◽  
Trichoderma Sp ◽  
Trichoderma Isolates

Biocontrol is an important aspect of disease management for plant pathogens, especially for the soil borne fungi. Trichoderma species is the most exploited biocontrol agent in recent years. The soil specific nature of Trichoderma species is a well-known fact and hence native Trichoderma isolates should be more emphasized for control of plant pathogens. Fifty soil samples from rhizosphere of various agricultural crops were collected for isolation of Trichoderma sp. Ten isolates of Trichoderma were tested in dual culture with soil borne pathogens Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum in an in vitro assay. All of the test isolates were found to be significant in terms of mycelial inhibition growth as compared to control. However, varying degrees of antagonism by different Trichoderma isolates were observed for above mentioned soil borne pathogens. The isolate (T363) was found to exhibit more than 80% inhibition of S. sclerotiorum while the isolate T357 was found to control F. solani by more than 80%.  For the control of R. solani, six of the tested Trichoderma isolates showed more than 80% inhibition of its radial colony growth. The Trichoderma isolates seen effective in this study need to be tested in pot and field experiments for exploiting the use and benefits of biocontrol.

scholarly journals IN VITRO PHARMACOLOGICAL SCREENING METHODS FOR ANTI-INFLAMMATORY AGENTS

2018 ◽  
Vol 11 ◽  
Author(s):  
Jayakumari S ◽  
Jijith Us
Keyword(s):  
Leukocyte Adhesion ◽  
Induced Response ◽  
Screening Methods ◽  
Adhesion Assay ◽  
Polymorphonuclear Cells ◽  
In Vitro Methods ◽  
Anti Inflammatory ◽  
Pharmacological Screening ◽  
New Compounds

Context: The development of in vitro methods is important in drug discovery process due to the restriction of animal use in the pharmacological screening process.Objective: The objective of the review was to understand the in vitro pharmacological screening methods for anti-inflammatory agents.Methods: The present review details various in vitro methods available for the screening of activity of therapeutic agents against inflammation.Results: Inhibition and measurement of nitric oxide production, mast cell degranulation, leukocyte adhesion assay, platelet-neutrophil adhesion assay, lipopolysaccharide-induced response assay, N-formyl-methionyl-leucyl-phenylalanine-induced O2 generation by polymorphonuclear cells, and cyclooxygenase assays are discussed in this review.Conclusions: These methods help to understand the real mechanism of inflammation and mediators involved in this process and help toidentify new compounds possessing the anti-inflammatory activity.

scholarly journals Commercial Biocontrol Agents Reveal Contrasting Comportments Against Two Mycotoxigenic Fungi in Cereals: Fusarium Graminearum and Fusarium Verticillioides

Toxins ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 152 ◽  
Author(s):  
Lucile Pellan ◽  
Noël Durand ◽  
Véronique Martinez ◽  
Angélique Fontana ◽  
Sabine Schorr-Galindo ◽  
...  
Keyword(s):  
Fusarium Graminearum ◽  
Culture Media ◽  
Fusarium Verticillioides ◽  
Inhibition Zone ◽  
Culture Conditions ◽  
Dual Culture ◽  
Growth Inhibition Zone ◽  
Mycotoxigenic Fungi ◽  
The Impact

The aim of this study was to investigate the impact of commercialized biological control agents (BCAs) against two major mycotoxigenic fungi in cereals, Fusarium graminearum and Fusarium verticillioides, which are trichothecene and fumonisin producers, respectively. With these objectives in mind, three commercial BCAs were selected with contrasting uses and microorganism types (T. asperellum, S. griseoviridis, P. oligandrum) and a culture medium was identified to develop an optimized dual culture bioassay method. Their comportment was examined in dual culture bioassay in vitro with both fusaria to determine growth and mycotoxin production kinetics. Antagonist activity and variable levels or patterns of mycotoxinogenesis inhibition were observed depending on the microorganism type of BCA or on the culture conditions (e.g., different nutritional sources), suggesting that contrasting biocontrol mechanisms are involved. S. griseoviridis leads to a growth inhibition zone where the pathogen mycelium structure is altered, suggesting the diffusion of antimicrobial compounds. In contrast, T. asperellum and P. oligandrum are able to grow faster than the pathogen. T. asperellum showed the capacity to degrade pathogenic mycelia, involving chitinolytic activities. In dual culture bioassay with F. graminearum, this BCA reduced the growth and mycotoxin concentration by 48% and 72%, respectively, and by 78% and 72% in dual culture bioassay against F. verticillioides. P. oligandrum progressed over the pathogen colony, suggesting a close type of interaction such as mycoparasitism, as confirmed by microscopic observation. In dual culture bioassay with F. graminearum, P. oligandrum reduced the growth and mycotoxin concentration by 79% and 93%, respectively. In the dual culture bioassay with F. verticillioides, P. oligandrum reduced the growth and mycotoxin concentration by 49% and 56%, respectively. In vitro dual culture bioassay with different culture media as well as the nutritional phenotyping of different microorganisms made it possible to explore the path of nutritional competition in order to explain part of the observed inhibition by BCAs.

Antifungal activity of extracts from endophytic fungi associated with Smallanthus maintained in vitro as autotrophic cultures and as pot plants in the greenhouse

2012 ◽  
Vol 58 (10) ◽  
pp. 1202-1211 ◽  
Author(s):  
Luiz H. Rosa ◽  
Nurhayat Tabanca ◽  
Natascha Techen ◽  
Zhiqiang Pan ◽  
David E. Wedge ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Endophytic Fungi ◽  
Plant Pathogens ◽  
Cultivation Conditions ◽  
Smallanthus Sonchifolius ◽  
Fungal Plant Pathogens ◽  
In The Wild ◽  
Fungal Assemblages ◽  
Pot Plants

The endophytic fungal assemblages associated with Smallanthus sonchifolius (Poepp.) H. Rob. and Smallanthus uvedalius (L.) Mack. ex Small growing in vitro autotrophic cultures and in the greenhouse were identified and evaluated for their ability to produce bioactive compounds. A total of 25 isolates were recovered that were genetically closely related to species of the genera Bionectria , Cladosporium , Colletotrichum , Fusarium , Gibberella , Hypocrea , Lecythophora , Nigrospora , Plectosphaerella , and Trichoderma . The endophytic assemblages of S. sonchifolius presented a greater diversity than the group isolated from S. uvedalius and demonstrated the presence of dominant generalist fungi. Extracts of all fungi were screened against the fungal plant pathogens. Ten extracts (41.6%) displayed antifungal activities; some of them had a broad antifungal activity. The phylotypes Lecythophora sp. 1, Lecythophora sp. 2, and Fusarium oxysporum were isolated from in vitro autotrophic cultures and displayed antifungal activity. The presence of bioactive endophytic fungi within S. sonchifolius and S. uvedalius suggests an ecological advantage against pathogenic attacks. This study revealed reduced numbers of endophytes in association with both Smallanthus species in controlled cultivation conditions compared with the endophytic communities of hosts collected in the wild environments. Even as reduced endophytic communities, these fungi continue to provide chemical protection for the host.

scholarly journals Inhibition of Phytophthora parasitica and P. capsici by Silver Nanoparticles Synthesized Using Aqueous Extract of Artemisia absinthium

2015 ◽  
Vol 105 (9) ◽  
pp. 1183-1190 ◽  
Author(s):  
Mohammad Ali ◽  
Bosung Kim ◽  
Kevin D. Belfield ◽  
David Norman ◽  
Mary Brennan ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Aqueous Extract ◽  
Dose Response ◽  
Mycelial Growth ◽  
Plant Pathogens ◽  
Synthesis Methods ◽  
In Planta ◽  
Artemisia Absinthium ◽  
Plant Disease Management

Application of nanoparticles for controlling plant pathogens is a rapidly emerging area in plant disease management, and nanoparticles synthesis methods that are economical and ecofriendly are extensively investigated. In this project, we investigated the potential of silver nanoparticles (AgNPs) synthesized with aqueous extract of Artemisia absinthium against several Phytophthora spp., which cause many economically important crop diseases. In in vitro dose-response tests conducted in microtiter plates, 10 µg ml−1 of AgNPs inhibited mycelial growth of P. parasitica, P. infestans, P. palmivora, P. cinnamomi, P. tropicalis, P. capsici, and P. katsurae. Detailed in vitro dose-response analyses conducted with P. parasitica and P. capsici revealed that AgNPs synthesized with A. absinthium extract were highly potent (IC50: 2.1 to 8.3 µg ml−1) and efficacious (100%) in inhibiting mycelial growth, zoospore germination, germ tube elongation, and zoospore production. Interestingly, AgNP treatment accelerated encystment of zoospores. Consistent with in vitro results, in planta experiments conducted in a greenhouse revealed that AgNP treatments prevented Phytophthora infection and improved plant survival. Moreover, AgNP in in planta experiments did not produce any adverse effects on plant growth. These investigations provide a simple and economical method for controlling Phytophthora with AgNP without affecting normal plant physiology.

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