scholarly journals Investigation of the Biocontrol Potential of Two Ash Endophytes against Hymenoscyphus fraxineus Using In Vitro Plant–Fungus Dual Cultures

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1750
Author(s):  
Katarzyna Nawrot-Chorabik ◽  
Natalia Marcol-Rumak ◽  
Dariusz Latowski
Keyword(s):  
Dual Culture ◽  
Hymenoscyphus Fraxineus ◽  
Dual Cultures ◽  
Large Numbers ◽  
Hplc Profiles ◽  
In Vitro Plant ◽  
Biocontrol Potential ◽  
The Impact ◽  
Selection Of

Development of effective biocontrol procedures using ash endophytes to combat an ash pathogen Hymenoscyphus fraxineus would be an appropriate contribution to the ongoing effort to protect European ash stands against ash decline. In this study we investigated the biocontrol potential of two ash endophytes, Thielavia basicola and Minimidochium sp., against H. fraxineus using in vitro plant-fungus and fungus-fungus dual cultures approach in three biocontrol models. The tests aimed to determine whether the endophytes show antagonism toward Fraxinus excelsior and F. pennsylvanica, to assess the level of antagonism of the endophytes toward H. fraxineus and to identify potential secondary metabolites induced by the presence of H. fraxineus. The results that dual culture experiments modeled according to our design may be a very useful tool to precisely study biocontrol potential of fungi, i.e., without the impact of environmental factors. Such experiments also enable the selection of most resistant ash genotypes and rapid propagation, producing large numbers of pathogen-free seedlings. It should be noted, however, that both of the endophytes tested in the dual cultures strongly inhibited the growth of H. fraxineus. Their growth under the influence of callus/seedlings was also inhibited. Comparison of HPLC profiles showed that the presence of H. fraxineus in the post-culture medium induced the production of an unknown secondary metabolite in this species. Such results suggest that some of the plant–fungus combinations examined in this study may have potential to be developed as biocontrol methods, thus increasing the survivability of ash stands under natural conditions.

scholarly journals In VivoTransmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

2015 ◽  
Vol 81 (10) ◽  
pp. 3561-3570 ◽  
Author(s):  
Timothy J. Johnson ◽  
Randall S. Singer ◽  
Richard E. Isaacson ◽  
Jessica L. Danzeisen ◽  
Kevin Lang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Dose ◽  
Broad Host Range ◽  
Antibiotic Administration ◽  
Dose Administration ◽  
Content Type ◽  
E Coli ◽  
The Impact ◽  
Selection Of

ABSTRACTIncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensalEscherichia colihost. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containingE. colifrom pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containingE. coliin pig feces (P< 0.001) and increased movement of the IncA/C plasmid to other indigenousE. colihosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other thanE. coli.In vitrocompetition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage inE. coliandSalmonella.In vitrotransfer and selection experiments demonstrated that tetracycline at 32 μg/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracyclinein vitrostrongly selected for IncA/C plasmid-containingE. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids.

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.

scholarly journals Biocontrol potential of Trichoderma harzianum in controlling wilt disease of pistachio caused by Verticillium dahliae

2017 ◽  
Vol 57 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Zeinab Fotoohiyan ◽  
Saeed Rezaee ◽  
Gholam Hosein Shahidi Bonjar ◽  
Amir Hossein Mohammadi ◽  
Mohammad Moradi
Keyword(s):  
Verticillium Dahliae ◽  
Trichoderma Harzianum ◽  
Pathogenic Fungus ◽  
Antagonistic Activity ◽  
Wilt Disease ◽  
Dual Culture ◽  
Volatile Metabolites ◽  
Biocontrol Potential

Abstract Verticillium wilt caused by Verticillium dahliae, is one of the most devastating diseases in pistachio orchards in the world including Iran. In search for an effective non-chemical strategy for the management of this disease, we evaluated the biocontrol potential of Trichoderma harzianum isolates obtained from the rhizosphere of healthy pistachio trees in different locations of the Kerman province of Iran against V. dahliae under laboratory and greenhouse conditions. Dual culture tests in the laboratory were conducted in a completely randomized design using 72 T. harzianum isolates. Twenty isolates showed the highest in vitro antagonistic activity. The results indicated that all 20 isolates were capable of inhibiting the mycelial growth of V. dahliae significantly. Among them, isolates Tr8 and Tr19 were the most effective by 88.89% and 85.12% inhibition, respectively. Extracted cell free metabolites of all effective isolates also inhibited the growth of V. dahliae in the culture medium significantly. According to the results, isolates Tr4 and Tr6 inhibited fungal pathogen growth by 94.94% and 88.15% respectively, through production of non-volatile metabolites. In the evaluation of volatile metabolites, isolates Tr5 and Tr4 were the most effective by 26.27% and 24.49% growth inhibition, respectively. Based on the results of the in vitro experiments, the five most effective isolates were selected for evaluation under greenhouse conditions for their biocontrol potential in controlling Verticillium wilt of pistachio. Results of the greenhouse, (in vivo) experiments were positive and indicated that the occurrence of wilt disease in plants treated with the antagonists alone or in combination with pathogenic fungus was lower than in plants inoculated with pathogen alone. The overall results of this study suggest that Trichoderma fungal antagonist may be an effective biocontrol agent for the control of Verticillium wilt of pistachio.

scholarly journals Isolation, Identification and In Vitro Test for the Biocontrol Potential of Trichoderma viride on Fusarium oxysporum f. sp. Lycopersici

2021 ◽  
Vol 15 (1) ◽  
pp. 10-20
Author(s):  
Tsegaye Mekuria Ayele ◽  
Guesh Desta Gebremariam ◽  
Subban Patharajan
Keyword(s):  
Fusarium Oxysporum ◽  
Trichoderma Viride ◽  
Dual Culture ◽  
In Vitro Test ◽  
Tomato Production ◽  
Biocontrol Efficacy ◽  
Pests And Diseases ◽  
Dual Culture Assay ◽  
Biocontrol Potential

Introduction: Tomato production in Ethiopia is challenged by many pests and diseases. Fusarium wilt is one of the most important diseases of tomato affecting its productivity. Methods: Tomato tissue and soil samples were collected from tomato farmlands around Aksum town to isolate and identify pathogenic Fusarium species and Trichoderma species with biocontrol efficacy. Samples were processed in the Aksum University Biotechnology laboratory following standard procedures. Results and Discussion: Eight Fusarium and five Trichoderma isolates were obtained. Six of the Fusarium isolates were identified as Fusarium oxysporum, whereas the remaining two were Fusarium equiseti and Fusarium circinatum. Detached leaf bioassay of the F. oxysporum on tomato leaves showed leaf lesion on the tomato variety, Melka oda. The isolated Trichoderma strains were screened for biocontrol potential against virulent F. oxysporum in vitro. The Trichoderma isolate showing the highest biocontrol efficacy against the virulent Fusarium was morphologically identified as Trichoderma viride. in vitro F. oxysporum-T. viride dual culture assay demonstrated that T. viride inhibits the growth of F. oxysporum f.sp. lycopersici with 76.94% growth inhibition. Conclusion: Fusarium oxysporum is prevalent in tomato growing farmlands covered in this study. T. viride identified in this study is an effective biocontrol agent for the identified F. oxysporum fsp. lycopersici in vitro.

scholarly journals In Vitro Interactions between Eutypella parasitica and Some Frequently Isolated Fungi from the Wood of the Dead Branches of Young Sycamore Maple (Acer pseudoplatanus)

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1072
Author(s):  
Ana Brglez ◽  
Barbara Piškur ◽  
Nikica Ogris
Keyword(s):  
Competitive Ability ◽  
Inhibitory Effect ◽  
Antagonistic Activity ◽  
Dual Culture ◽  
Acer Pseudoplatanus ◽  
Dual Cultures ◽  
Weak Competitor ◽  
The Dead ◽  
In Vitro Interactions

The ten most frequently isolated fungi from the wood of the dead branches of Acer pseudoplatanus L. were tested in dual cultures to evaluate their in vitro antagonistic activity against Eutypella parasitica R.W. Davidson and R.C. Lorenz, the causative agent of a destructive disease of maples in Europe and North America. The tested fungi, treated also as challenge isolates, were Diaporthe sp., Eutypa sp., Eu. maura, E. parasitica, Fusarium avenaceum, Neocucurbitaria acerina, Neonectria sp., Peniophora incarnata, Petrakia irregularis, and Phomopsis pustulata. The antagonistic ability of each challenge isolate was evaluated by calculating an index of antagonism (AI) based on the interaction type in the dual cultures. The results of competition between the fungal isolates were quantified after re-isolations from the interaction zone (s). The dual cultures revealed two main types of competitive interactions: Deadlock, consisting of mutual inhibition after mycelial contact or at a distance, and replacement, reflecting in the inhibition of E. parasitica, followed by partial overgrowth by the replacing fungus. Statistical analysis showed significant differences in average AI and s of challenge isolates between different dual culture assays. Based on the results of the antagonism index, Eutypa sp., Eu. maura, Neonectria sp., and P. incarnata had the highest inhibitory effect on E. parasitica growth and were recognized as the most promising candidates for further biocontrol studies of E. parasitica. The mycelium of E. parasitica at the interaction zones remained mostly viable, except in dual cultures with Eutypa sp., F. avenaceum, and Neonectria sp., where re-isolations did not yield any colony of the E. parasitica isolate. Based on the results, we assume that E. parasitica is a weak competitor, which invests less energy in direct mycelial competition. We discuss the potential of the observed antagonists as a possible biocontrol of Eutypella canker of maple. Nevertheless, additional experiments should be performed for a solid conclusion about competitive ability of E. parasitica and usefulness of antagonists as biocontrol.

scholarly journals Development-Related miRNA Expression and Target Regulation during Staggered In Vitro Plant Regeneration of Tuxpeño VS-535 Maize Cultivar

2019 ◽  
Vol 20 (9) ◽  
pp. 2079 ◽  
Author(s):  
Brenda A. López-Ruiz ◽  
Vasti T. Juárez-González ◽  
Estela Sandoval-Zapotitla ◽  
Tzvetanka D. Dinkova
Keyword(s):  
Plant Regeneration ◽  
Callus Induction ◽  
In Vitro Regeneration ◽  
In Vitro Plant Regeneration ◽  
Embryogenic Calli ◽  
Target Regulation ◽  
In Vitro Plant ◽  
The Impact ◽  
Embryogenic Tissues

In vitro plant regeneration addresses basic questions of molecular reprogramming in the absence of embryonic positional cues. The process is highly dependent on the genotype and explant characteristics. However, the regulatory mechanisms operating during organ differentiation from in vitro cultures remain largely unknown. Recently, miRNAs have emerged as key regulators during embryogenic callus induction, plant differentiation, auxin responses and totipotency. Here, we explored how development-related miRNA switches the impact on their target regulation depending on physiological and molecular events taking place during maize Tuxpeño VS-535 in vitro plant regeneration. Three callus types with distinctive regeneration potential were characterized by microscopy and histological preparations. The embryogenic calli (EC) showed higher miRNA levels than non-embryogenic tissues (NEC). An inverse correlation for miR160 and miR166 targets was found during EC callus induction, whereas miR156, miR164 and miR394 displayed similar to their targets RNA accumulation levels. Most miRNA accumulation switches took place early at regenerative spots coincident with shoot apical meristem (SAM) establishment, whereas miR156, miR160 and miR166 increased at further differentiation stages. Our data uncover particular miRNA-mediated regulation operating for maize embryogenic tissues, supporting their regulatory role in early SAM establishment and basipetala growth during the in vitro regeneration process.

scholarly journals Transmitted Human Immunodeficiency Virus Type 1 Carrying the D67N or K219Q/E Mutation Evolves Rapidly to Zidovudine Resistance In Vitro and Shows a High Replicative Fitness in the Presence of Zidovudine

2004 ◽  
Vol 78 (14) ◽  
pp. 7545-7552 ◽  
Author(s):  
J. Gerardo García-Lerma ◽  
Hamish MacInnes ◽  
Diane Bennett ◽  
Hillard Weinstock ◽  
Walid Heneine
Keyword(s):  
Resistance Mutations ◽  
Immunodeficiency Virus ◽  
Evolution Of Resistance ◽  
Drug Naïve ◽  
Azt Resistance ◽  
The Impact ◽  
Hiv 1 ◽  
Selection Of

ABSTRACT Drug-naive patients infected with drug-resistant human immunodeficiency virus type 1 (HIV-1) who initiate antiretroviral therapy show a shorter time to virologic failure than patients infected with wild-type (WT) viruses. Resistance-related HIV genotypes not commonly seen in treated patients, which likely result from reversion or loss of primary resistance mutations, have also been recognized in drug-naive persons. Little work has been done to characterize the patterns of mutations in these viruses and the frequency of occurrence, their association with phenotypic resistance, and their effect on fitness and evolution of resistance. Through the analysis of resistance mutations in 1082 newly diagnosed antiretroviral-naive persons from the United States, we found that 35 of 48 (72.9%) persons infected with HIV-1 containing thymidine analog mutations (TAMs) had viruses that lacked a primary mutation (T215Y/F, K70R, or Q151M). Of these viruses, 9 (25.7%) had only secondary TAMs (D67N, K219Q, M41L, or F77L), and all were found to be sensitive to zidovudine (AZT) and other drugs. To assess the impact of secondary TAMs on the evolution of AZT resistance, we generated recombinant viruses from cloned plasma-derived reverse transcriptase sequences. Two viruses had D67N, three had D67N and K219Q/E, and three were WT. Four site-directed mutants with D67N, K219Q, K219E, and D67N/K219Q were also made in HIV-1HXB2. In vitro selection of AZT resistance showed that viruses with D67N and/or K219Q/E acquired AZT resistance mutations more rapidly than WT viruses (36 days compared to 54 days; P = 0.003). To investigate the factors associated with the rapid selection of AZT mutations in these viruses, we evaluated fitness differences among HXB2WT and HXB2D67N or HXB2D67N/K219Q in the presence of AZT. Both HXB2D67N/K219Q and HXB2D67N were more fit than HXB2WT in the presence of either low or high AZT concentrations, likely reflecting low-level resistance to AZT that is not detectable by phenotypic testing. In the absence of AZT, the fitness cost conferred by D67N or K219Q was modest. Our results demonstrate that viruses with unique patterns of TAMs, including D67N and/or K219Q/E, are commonly found among newly diagnosed persons and illustrate the expanding diversity of revertant viruses in this population. The modest fitness cost conferred by D67N and K219Q supports persistence of these mutants in the untreated population and highlights the potential for secondary transmission. The faster evolution of these mutants toward AZT resistance is consistent with the higher viral fitness in the presence of AZT and shows that these viruses are phenotypically different from WT HIV-1. Our study emphasizes the need for clinical studies to better define the impact of these mutants on treatment responses and evolution of resistance.

scholarly journals Permissive aggregative group formation favors coexistence in yeast

2021 ◽  
Author(s):  
Tom E. R. Belpaire ◽  
Jiří Pešek ◽  
Bram Lories ◽  
Kevin J. Verstrepen ◽  
Hans P. Steenackers ◽  
...  
Keyword(s):  
Kin Recognition ◽  
Group Formation ◽  
Cluster Formation ◽  
Dual Function ◽  
Bond Stability ◽  
Selective Pressures ◽  
Formation And Evolution ◽  
The Impact ◽  
Selection Of

ABSTRACTIn Saccharomyces cerevisiae, the FLO1 gene encodes flocculins that lead to formation of multicellular flocs, that offer protection to the constituent cells. Flo1p was found to preferentially bind to fellow cooperators compared to defectors lacking FLO1 expression, resulting in enrichment of cooperators within the flocs. Given this dual function in cooperation and kin recognition, FLO1 has been termed a ‘green beard gene’. Because of the heterophilic nature of Flo1p binding however, we hypothesize that kin recognition is permissive and depends on the relative stability of FLO1+/flo1− versus FLO1+/FLO1+ bonds, which itself can be dependent on environmental conditions and intrinsic cell properties. We combine single cell measurements of adhesion strengths, individual cell-based simulations of cluster formation and evolution, and in vitro flocculation experiments to study the impact of relative bond stability on defector exclusion as well as benefit and stability of cooperation. We hereto vary the relative bond stability by changing the shear flow rate and the inherent bond strength. We identify a marked trade-off between both aspects of the green beard mechanism, with reduced relative bond stability leading to increased kin recognition, but at the expense of decreased cluster sizes and benefit of cooperation. Most notably, we show that the selection of FLO1 cooperators is negative-frequency dependent, which we directly attribute to the permissive character of the Flo1p bond. Taking into account the costs associated to FLO1 expression, this asymmetric selection results in a broad range of ecological conditions where coexistence between cooperators and defectors is stable. Although the kin recognition aspect of the FLO1 ‘green beard gene’ is thus limited and condition dependent, the negative-frequency dependency of selection can conserve the diversity of flocculent and non-flocculent phenotypes ensuring flexibility towards variable selective pressures.

scholarly journals Single-cell analysis reveals selection of TP53-mutated clones after MDM2 inhibition

2022 ◽  
Author(s):  
Nabih Maslah ◽  
Emmanuelle Verger ◽  
Stéphane Giraudier ◽  
Mathias Chea ◽  
Ronald Hoffman ◽  
...  
Keyword(s):  
Single Cell ◽  
Single Cell Analysis ◽  
Selection Process ◽  
Myeloproliferative Neoplasms ◽  
Clonal Evolution ◽  
In Vitro Test ◽  
Tp53 Mutations ◽  
The Impact ◽  
Selection Of

The mechanisms of transformation of chronic myeloproliferative neoplasms (MPN) to leukemia are largely unknown but TP53mutations acquisition is considered a key event in this process. P53 is a main tumor suppressor but mutations in this protein per se do not confer a proliferative advantage to the cells and a selection process is needed for the expansion of mutant clones. MDM2 inhibitors may rescue normal p53 from degradation and have been evaluated in a variety of cancers with promising results. However the impact of these drugs on TP53 mutated cells is underexplored. We report herein evidence of a direct effect of MDM2 inhibition on the selection of MPN patients' cells harboring TP53 mutations. To decipher whether these mutations can arise in a specific molecular context we used a DNA single cell approach to determine the clonal architecture of TP53 mutated cells. We observed that TP53 mutations are late events in MPN mainly occurring in the driver clone while clonal evolution frequently consists of sequential branching instead of linear consecutive acquisition of mutations in the same clone. At the single cell level the presence of additional mutations does not influence the selection of TP53 mutant cells by MDM2 inhibitor treatment. Also, we describe an in vitro test allowing to predict the emergence of TP53 mutated clones. Altogether, this is the first demonstration that a drug treatment can directly favor the emergence of TP53-mutated subclones in MPN.

scholarly journals EXPLORATION AND SELECTION OF RHIZOBACTERIA THAT INHIBIT PHYTOPHTHORA CAPSICI IN VITRO

2018 ◽  
Vol 18 (1) ◽  
pp. 83
Author(s):  
Aulia Zakia ◽  
Satriyas Ilyas ◽  
Candra Budiman ◽  
Syamsuddin . ◽  
Dyah Manohara
Keyword(s):  
Phytophthora Capsici ◽  
Culture Method ◽  
Healthy Plant ◽  
Dual Culture ◽  
Phytophthora Blight ◽  
Heated Sample ◽  
Resistant Varieties ◽  
Blight Disease ◽  
Selection Of

Exploration and Selection of Rhizobacteria that Inhibit Phytophthora capsici in vitro. Phytophthora capsici, a seed borne and the soil borne fungal pathogen is the cause of phytophthora blight on chili. The disease is difficult to control because of the resistant varieties unavailability in Indonesia. The aimed was to obtain isolates of rhizobacteria which has the ability to inhibit P. capsici in vitro. Rhizobacteria exploration was conducted in the chili production center in East Java (Malang, Batu, and Kediri) and West Java (Bogor). In one location, chili plant that had symptoms of phytophthora blight disease and a healthy plant next to it were chosen as samples to isolate P. capsici and the rhizobacteria. The rhizobacteria were isolated on NA, TSA, and TSAP (TSA with heated sample). Samples of diseased plants were used in isolation of P. capsici on V8 agar. The inhibition and compatibility of the rhizobacteria to inhibit P. capsici in vitro were tested by dual culture method. In this experiment, it was obtained 252 isolates of rhizobacteria and one isolate of P. capsici. Isolates of rhizobacteria with high to medium inhibition were E1, E3C2, and F2B1 respectively. All three isolates were then combined and tested against P. capsici in vitro. The highest inhibition was indicated by four isolate and combination of isolates, which were E1 isolate (58%), the combination of E1 + E3C2 isolates (58%), E1 + F2B1 (60%) and E1 + E3C2 + F2B1 (58 %).

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