scholarly journals Transcriptional Profiling of Diffusible Lipopeptides and Fungal Virulence Genes During Bacillus amyloliquefaciens EZ1509-Mediated Suppression of Sclerotinia sclerotiorum

2020 ◽  
Vol 110 (2) ◽  
pp. 317-326 ◽  
Author(s):  
Ayaz Farzand ◽  
Anam Moosa ◽  
Muhammad Zubair ◽  
Abdur Rashid Khan ◽  
Muhammad Ayaz ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Bacillus Amyloliquefaciens ◽  
Virulence Genes ◽  
Mass Spectrometry Analysis ◽  
Dual Culture ◽  
Biosynthetic Genes ◽  
In Vitro Interaction

Sclerotinia sclerotiorum is a devastating necrotrophic pathogen that infects multiple crops, and its control is an unremitting challenge. In this work, we attempted to gain insights into the pivotal role of lipopeptides (LPs) in the antifungal activity of Bacillus amyloliquefaciens EZ1509. In a comparative study involving five Bacillus strains, B. amyloliquefaciens EZ1509 harboring four LPs biosynthetic genes (viz. surfactin, iturin, fengycin, and bacilysin) exhibited promising antifungal activity against S. sclerotiorum in a dual-culture assay. Our data demonstrated a remarkable upsurge in LPs biosynthetic gene expression through quantitative reverse transcription PCR during in vitro interaction assay with S. sclerotiorum. Maximum upregulation in LPs biosynthetic genes was observed on the second and third days of in vitro interaction, with iturin and fengycin being the highly expressed genes. Subsequently, Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry analysis confirmed the presence of LPs in the inhibition zone. Scanning electron microscope analysis showed disintegration, shrinkage, plasmolysis, and breakdown of fungal hyphae. During in planta evaluation, S. sclerotiorum previously challenged with EZ1509 showed significant suppression in pathogenicity on detached leaves of tobacco and rapeseed. The oxalic acid synthesis was also significantly reduced in S. sclerotiorum previously confronted with antagonistic bacterium. The expression of major virulence genes of S. sclerotiorum, including endopolygalacturonase-3, oxalic acid hydrolase, and endopolygalacturonase-6, was significantly downregulated during in vitro confrontation with EZ1509.

Stringent response mutants of Pseudomonas chlororaphis PA23 exhibit enhanced antifungal activity against Sclerotinia sclerotiorum in vitro

Microbiology ◽  
2012 ◽  
Vol 158 (1) ◽  
pp. 207-216 ◽  
Author(s):  
Jerrylynn Manuel ◽  
Carrie Selin ◽  
W. G. Dilantha Fernando ◽  
Teresa de Kievit
Keyword(s):  
Antifungal Activity ◽  
Sclerotinia Sclerotiorum ◽  
Stringent Response ◽  
Pseudomonas Chlororaphis

scholarly journals Novel Antifungal Activity of Lolium-Associated Epichloë Endophytes

2020 ◽  
Vol 8 (6) ◽  
pp. 955 ◽  
Author(s):  
Krishni Fernando ◽  
Priyanka Reddy ◽  
Inoka K. Hettiarachchige ◽  
German C. Spangenberg ◽  
Simone J. Rochfort ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Insect Pests ◽  
Fungal Endophytes ◽  
Dual Culture ◽  
The Novel ◽  
In Planta ◽  
Pasture Production ◽  
Fusarium Sp ◽  
Invertebrate Pests

Asexual Epichloë spp. fungal endophytes have been extensively studied for their functional secondary metabolite production. Historically, research mostly focused on understanding toxicity of endophyte-derived compounds on grazing livestock. However, endophyte-derived compounds also provide protection against invertebrate pests, disease, and other environmental stresses, which is important for ensuring yield and persistence of pastures. A preliminary screen of 30 strains using an in vitro dual culture bioassay identified 18 endophyte strains with antifungal activity. The novel strains NEA12, NEA21, and NEA23 were selected for further investigation as they are also known to produce alkaloids associated with protection against insect pests. Antifungal activity of selected endophyte strains was confirmed against three grass pathogens, Ceratobasidium sp., Dreschlera sp., and Fusarium sp., using independent isolates in an in vitro bioassay. NEA21 and NEA23 showed potent activity against Ceratobasidium sp. and NEA12 showed moderate inhibition against all three pathogens. Crude extracts from liquid cultures of NEA12 and NEA23 also inhibited growth of the phytopathogens Ceratobasidium sp. and Fusarium sp. and provided evidence that the compounds of interest are stable, constitutively expressed, and secreted. Comparative analysis of the in vitro and in planta metabolome of NEA12 and NEA23 using LCMS profile data revealed individual metabolites unique to each strain that are present in vitro and in planta. These compounds are the best candidates for the differential bioactivity observed for each strain. Novel endophyte strains show promise for endophyte-mediated control of phytopathogens impacting Lolium spp. pasture production and animal welfare.

scholarly journals The Sclerotinia sclerotiorum pac1 Gene Is Required for Sclerotial Development and Virulence

2003 ◽  
Vol 16 (9) ◽  
pp. 785-795 ◽  
Author(s):  
Jeffrey A. Rollins
Keyword(s):  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Acid Production ◽  
Plant Pathogens ◽  
Gene Replacement ◽  
Loss Of Function ◽  
Physiological Processes ◽  
Gene Transcripts ◽  
Sclerotial Development

The synergistic activities of oxalic acid and endopolygalacturonases are thought to be essential for full virulence of Sclerotinia sclerotiorum and other oxalate-producing plant pathogens. Both oxalic acid production and endopolygalacturonase activity are regulated by ambient pH. Since many gene products with pH-sensitive activities are regulated by the PacC transcription factor in Aspergillus nidulans, we functionally characterized a pacC gene homolog, pac1, from S. sclerotiorum. Mutants with loss-of-function alleles of the pac1 locus were created by targeted gene replacement. In vitro mycelial growth of these pac1 mutants was normal at acidic pH, but growth was inhibited as culture medium pH was increased. Development and maturation of sclerotia in culture was also aberrant in these pac1 replacement mutants. Although oxalic acid production remained alkaline pH-responsive, the kinetics and magnitude of oxalate accumulation were dramatically altered. Additionally, maximal accumulation of endopolygalacturonase gene transcripts (pg1) was shifted to higher ambient pH. Virulence in loss-of-function pac1 mutants was dramatically reduced in infection assays with tomato and Arabidopsis. Based on these results, pac1 appears to be necessary for the appropriate regulation of physiological processes important for pathogenesis and development of S. sclerotiorum.

scholarly journals Comparison of the composition and fungicidal activity of essential oils from fennel fruits cultivated in Poland and Egypt

2019 ◽  
Vol 21 (2) ◽  
pp. 38-42
Author(s):  
Alicja Wodnicka ◽  
Elżbieta Huzar ◽  
Małgorzata Dzięcioł ◽  
Maria Krawczyk
Keyword(s):  
Antifungal Activity ◽  
Essential Oil ◽  
Essential Oils ◽  
Sclerotinia Sclerotiorum ◽  
Plant Material ◽  
Fungicidal Activity ◽  
Pathogenic Fungi ◽  
Main Component ◽  
Essential Oil Yield

Abstract The yield, composition and fungicidal activity of essential oils obtained from fennel fruits cultivated in Poland (FEOPOL) and Egypt (FEO-EG) were compared. The influence of the duration of hydrodistillation using a Clevenger apparatus on the essential oil yield was studied. The composition of the fennel essential oils was determined by GC-MS method. Studies have shown that FEO-POL and FEO-EG are two distinct chemotypes, which differ in yield and composition. The fennel fruits cultivated in Poland contained 4.14% of essential oil with trans-anethole as a main component. The plant material from Egypt was characterised by low content of essential oil (1.32%) with a predominant share of estragole. The fungicidal activity was tested in vitro against ten species of pathogenic fungi. The best result for FEO-POL was achieved against Sclerotinia sclerotiorum, Rhizoctonia solani and Botrytis cinerea. Antifungal activity of FEO-EG against tested fungi was weak or none.

scholarly journals Cross Talk between 2,4-Diacetylphloroglucinol-Producing Biocontrol Pseudomonads on Wheat Roots

2004 ◽  
Vol 70 (4) ◽  
pp. 1990-1998 ◽  
Author(s):  
Monika Maurhofer ◽  
Eric Baehler ◽  
Regina Notz ◽  
Vicente Martinez ◽  
Christoph Keel
Keyword(s):  
Biocontrol Agent ◽  
Plant Diseases ◽  
Dual Culture ◽  
Antimicrobial Compound ◽  
Biosynthetic Genes ◽  
Wheat Roots ◽  
Wheat Seedlings ◽  
Root Diseases ◽  
Pathogen Inhibition

ABSTRACT The performance of Pseudomonas biocontrol agents may be improved by applying mixtures of strains which are complementary in their capacity to suppress plant diseases. Here, we have chosen the combination of Pseudomonas fluorescens CHA0 with another well-characterized biocontrol agent, P. fluorescens Q2-87, as a model to study how these strains affect each other's expression of a biocontrol trait. In both strains, production of the antimicrobial compound 2,4-diacetylphloroglucinol (DAPG) is a crucial factor contributing to the suppression of root diseases. DAPG acts as a signaling compound inducing the expression of its own biosynthetic genes. Experimental setups were developed to investigate whether, when combining strains CHA0 and Q2-87, DAPG excreted by one strain may influence expression of DAPG-biosynthetic genes in the other strain in vitro and on the roots of wheat. DAPG production was monitored by observing the expression of lacZ fused to the biosynthetic gene phlA of the respective strain. Dual-culture assays in which the two strains were grown in liquid medium physically separated by a membrane revealed that Q2-87 but not its DAPG-negative mutant Q2-87::Tn5-1 strongly induced phlA expression in a ΔphlA mutant of strain CHA0. In the same way, phlA expression in a Q2-87 background was induced by DAPG produced by CHA0. When coinoculated onto the roots of wheat seedlings grown under gnotobiotic conditions, strains Q2-87 and CHA0, but not their respective DAPG-negative mutants, were able to enhance phlA expression in each other. In summary, we have established that two nonrelated pseudomonads may stimulate each other in the expression of an antimicrobial compound important for biocontrol. This interpopulation communication occurs in the rhizosphere, i.e., at the site of pathogen inhibition, and is mediated by the antimicrobial compound itself acting as a signal exchanged between the two pseudomonads.

scholarly journals Deciphering the Bacillus amyloliquefaciens B9601-Y2 as a Potential Antagonist of Tobacco Leaf Mildew Pathogen During Flue-Curing

2021 ◽  
Vol 12 ◽  
Author(s):  
Zuxian Pan ◽  
Shahzad Munir ◽  
Yongmei Li ◽  
Pengbo He ◽  
Pengfei He ◽  
...  
Keyword(s):  
Bacillus Amyloliquefaciens ◽  
Mycelial Growth ◽  
Rhizopus Oryzae ◽  
Dual Culture ◽  
Tobacco Leaves ◽  
Tobacco Leaf ◽  
Antifungal Activities ◽  
Application Methods ◽  
Potential Antagonist

Tobacco leaf mildew caused by Rhizopus oryzae (Mucorales, Zygomycota) is an important and devastating post-harvest disease during flue-cured tobacco period, and also is known to cause diseases of fruits and vegetables. In this study, assessment of several candidate biological control agents were first tested in vitro to determine their antifungal activities and potential strains were further applied to tobacco leaves to prevent pathogen colonization during the tobacco-curing process. In vitro screening of 36 bacteria and the isolates of one fungus were performed for their antifungal activities against R. oryzae using dual culture method. Potential five isolates viz. Bacillus amyloliquefaciens B9601-Y2 (Y2), B. amyloliquefaciens YN201728 (YN28), Pseudomonas sp. (Pb), and B. amyloliquefaciens YN201732 (YN32) and T. harzianum B (Th-B) from total screened isolates have shown remarkable results for controlling the mycelial growth of R. oryzae. Finally, out of these five isolates, B. amyloliquefaciens B9601-Y2 potentially reduced the mycelial growth of fungal pathogen with great inhibitory effect. In order to get a better understanding of the biocontrol effect of B9601-Y2 in a flue-curing barn, various suspension density tests with two application methods involving spraying and soaking were examined. Two application methods of B. amyloliquefaciens B9601-Y2 had 98.60 and 98.15% control effects, respectively. In curing barn, the incidence in the treatment group was significantly reduced and tobacco leaves did not get mildew. Altogether, the study demonstrated that candidate bacterial strain B. amyloliquefaciens B9601-Y2 is a potential antagonist for the management of tobacco leaf mildew during flue-curing.

scholarly journals Evaluation of Antifungal Activity of Antagonistic Bacteria against Butt Rot Disease Pathogen of Pineapple

2017 ◽  
Vol 15 (4) ◽  
pp. 283-293 ◽  
Author(s):  
Mat Nawi NURNADIRAH ◽  
Kartini Che Mohd Ramli NENI ◽  
Mohd Yunus Nor YUZIAH
Keyword(s):  
Antifungal Activity ◽  
Pathogenic Fungi ◽  
Culture Method ◽  
Antagonistic Activity ◽  
Dual Culture ◽  
Butt Rot ◽  
Additional Control ◽  
Inhibitory Potential ◽  
Rot Disease

Butt rot disease, caused by Thielaviopsis paradoxa (De Seynes) Hohn., is one of the major diseases in pineapple cultivation in Malaysia. The objectives of this study were to evaluate the antifungal effect of antagonist bacteria against T. paradoxa, a causal agent of butt rot disease, and to observe the mechanism of antifungal activity of tested antagonist bacteria microscopically. In this study, in vitro antifungal potential of 5 antagonist bacteria, namely B1, B2, B3, B4, and B5, were isolated from infected and non-infected soil samples and evaluated using dual culture method against T. paradoxa. The mechanisms of antifungal activities of antagonist bacteria against the pathogen were microscopically observed. All of the bacteria showed inhibitory effects against the pathogenic fungi. B1 bacteria showed the highest inhibitory potential, with 73 % inhibition, followed by B2, B3, B4, and B5, with 71, 57, 56, and 48 % of inhibition compared to control, respectively. The results also showed that B2, B3, and B4 bacteria exhibited positive inhibition towards the pathogen, with more than 50 % percentage inhibition. The development of a new product for use as a biocontrol agent, used as an additional control or used in combination with existing ones, may reduce dependency on chemical control and increase antagonistic activity efficiency.

scholarly journals Antifungal activity of Bacillus amyloliquefaciens against Fusarium oxysporum f. sp. cubense race 1

2021 ◽  
pp. 466-478
Author(s):  
Mileidy Cruz Martín ◽  
Liliana Leyva ◽  
Mayra Acosta Suárez ◽  
Tatiana Pichardo ◽  
Idalmis Bermúdez Caraballoso ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Culture Filtrate ◽  
Bacillus Amyloliquefaciens ◽  
Biological Control Agent ◽  
Antifungal Effect ◽  
Antagonistic Microorganisms ◽  
Race 1

Introduction. Due to the absence of totally effective either economically viable chemical agents for the control of Fusarium wilt, the use of antagonistic microorganisms is of great interest since it could represent a more economically and ecologically sustainable alternative. Objective. To analyze the antifungal effect of the Bacillus amyloliquefaciens CCIBP-A5 strain against Fusarium oxysporum. Materials and methods. The work was carried out in the Laboratory of Applied Microbiology of the Instituto de Biotecnología de las Plantas, Cuba, between September 2017 and June, 2018. The in vitro and in vivo antifungal activity of its culture filtrate and cell against F. oxysporum has been assayed. Results. The results indicated that the metabolites present in the culture filtrate of B. amyloliquefaciens CCIBP-A5 significantly influenced the growth and morphology of the mycelium and the conidia. They also caused oxidative damage to the lipid molecules of F. oxysporum. In addition, this strain showed inhibitory effects on the development of the disease under controlled conditions. These aspects are key when selecting a bacterial candidate as a biological control agent. Conclusions. The results showed that the B. amyloliquefaciens CCIBP-A5 strain, isolated from Musa sp., had an in vitro antifungal effect against the vegetative and reproductive structures of Foc race 1 as well as on the Musa spp.-F. oxysporum interaction. This strain is suggested for the development of a bioproduct for Fusarium wilt management.

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