scholarly journals The Known Antimammalian and Insecticidal Alkaloids Are Not Responsible for the Antifungal Activity of Epichloë Endophytes

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2486
Author(s):  
Krishni Fernando ◽  
Priyanka Reddy ◽  
Simone Vassiliadis ◽  
German C. Spangenberg ◽  
Simone J. Rochfort ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Insect Pests ◽  
Ergot Alkaloids ◽  
In Planta ◽  
Turf Quality ◽  
Growth Area ◽  
Pasture Grasses ◽  
Lolitrem B ◽  
Epichloë Endophytes

Asexual Epichloë sp. endophytes in association with pasture grasses produce agronomically important alkaloids (e.g., lolitrem B, epoxy-janthitrems, ergovaline, peramine, and lolines) that exhibit toxicity to grazing mammals and/or insect pests. Novel strains are primarily characterised for the presence of these compounds to ensure they are beneficial in an agronomical setting. Previous work identified endophyte strains that exhibit enhanced antifungal activity, which have the potential to improve pasture and turf quality as well as animal welfare through phytopathogen disease control. The contribution of endophyte-derived alkaloids to improving pasture and turf grass disease resistance has not been closely examined. To assess antifungal bioactivity, nine Epichloë related compounds, namely peramine hemisulfate, n-formylloline-d3, n-acetylloline hydrochloride, lolitrem B, janthitrem A, paxilline, terpendole E, terpendole C, and ergovaline, and four Claviceps purpurea ergot alkaloids, namely ergotamine, ergocornine, ergocryptine, and ergotaminine, were tested at concentrations higher than observed in planta in glasshouse and field settings using in vitro agar well diffusion assays against three common pasture and turf phytopathogens, namely Ceratobasidium sp., Drechslera sp., and Fusarium sp. Visual characterisation of bioactivity using pathogen growth area, mycelial density, and direction of growth indicated no inhibition of pathogen growth. This was confirmed by statistical analysis. The compounds responsible for antifungal bioactivity of Epichloë endophytes hence remain unknown and require further investigation.

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 A Metabolomic Study of Epichloë Endophytes for Screening Antifungal Metabolites

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Krishni Fernando ◽  
Priyanka Reddy ◽  
Kathryn M. Guthridge ◽  
German C. Spangenberg ◽  
Simone J. Rochfort
Keyword(s):  
Phytopathogenic Fungi ◽  
Bioactive Metabolites ◽  
Symbiotic Association ◽  
In Planta ◽  
Vitro Assay ◽  
Antifungal Metabolites ◽  
Bioassay Guided Fractionation ◽  
Toxic Alkaloids ◽  
Epichloë Endophytes

Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, ‘animal friendly’ Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The “known unknown” suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.

scholarly journals Antifungal Activity of Silver Ions and Nanoparticles on Phytopathogenic Fungi

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 1037-1043 ◽  
Author(s):  
Young-Ki Jo ◽  
Byung H. Kim ◽  
Geunhwa Jung
Keyword(s):  
Antifungal Activity ◽  
Colony Formation ◽  
Magnaporthe Grisea ◽  
Silver Ions ◽  
Pathogenic Fungi ◽  
Chloride Ions ◽  
Plant Diseases ◽  
Plant Pathogenic Fungi ◽  
In Planta

Silver in ionic or nanoparticle forms has a high antimicrobial activity and is therefore widely used for various sterilization purposes including materials of medical devices and water sanitization. There have been relatively few studies on the applicability of silver to control plant diseases. Various forms of silver ions and nanoparticles were tested in the current study to examine the antifungal activity on two plant-pathogenic fungi, Bipolaris sorokiniana and Magnaporthe grisea. In vitro petri dish assays indicated that silver ions and nanoparticles had a significant effect on the colony formation of these two pathogens. Effective concentrations of the silver compounds inhibiting colony formation by 50% (EC50) were higher for B. sorokiniana than for M. grisea. The inhibitory effect on colony formation significantly diminished after silver cations were neutralized with chloride ions. Growth chamber inoculation assays further confirmed that both ionic and nanoparticle silver significantly reduced these two fungal diseases on perennial ryegrass (Lolium perenne). Particularly, silver ions and nanoparticles effectively reduced disease severity with an application at 3 h before spore inoculation, but their efficacy significantly diminished when applied at 24 h after inoculation. The in vitro and in planta evaluations of silver indicated that both silver ions and nanoparticles influence colony formation of spores and disease progress of plant-pathogenic fungi. In planta efficacy of silver ions and nanoparticles is much greater with preventative application, which may promote the direct contact of silver with spores and germ tubes, and inhibit their viability.

scholarly journals Fungal Endophytes Control Fusarium graminearum and Reduce Trichothecenes and Zearalenone in Maize

Toxins ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 493 ◽  
Author(s):  
Mohamed F. Abdallah ◽  
Marthe De Boevre ◽  
Sofie Landschoot ◽  
Sarah De Saeger ◽  
Geert Haesaert ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Graminearum ◽  
Fungal Endophytes ◽  
Agricultural Science ◽  
Ear Rot ◽  
Seedling Blight ◽  
In Planta ◽  
Detoxification Mechanisms ◽  
Comparative Trials

Fusarium graminearum can cause Giberella Ear Rot (GER) and seedling blight in maize, resulting in major yield losses. Besides GER, the infected grains are consequently contaminated with multiple mycotoxins of F. graminearum. Zearalenone and trichothecenes, such as deoxynivalenol and its acetylated forms, are among the major mycotoxins associated with F. graminearum infection in maize. In the current work, we explored the effect of the endophytic fungal genera of Epicoccum and Sordaria, to control F. graminearum infection in comparative trials with Piriformospora spp., an elusive endophytic genus. Furthermore, we investigated the effect of these endophytes on zearalenone, deoxynivalenol, and 15-acetyldeoxynivalenol levels using in vitro and in planta assays. As plants are endowed with several detoxification mechanisms comprising e.g., glucosylation of trichothecenes, the effect of the isolated fungal endophytes on the deoxynivalenol-3-glucoside level was also assessed. In general, results showed a considerable variability in the antifungal activity, both among species and among isolates within one species. Additionally, the effect on mycotoxin levels was variable, and not necessarily related to the antifungal activity except for zearalenone levels which were consistently reduced by the endophytes. These results highlight the great potential of certain endophytic fungal strains as new biocontrol agents in agricultural science.

A Laminarin-Based Formulation Protects Wheat Against Zymoseptoria tritici Via Direct Antifungal Activity and Elicitation of Host Defense-Related Genes

Plant Disease ◽  
2022 ◽  
Author(s):  
Marlon C. de Borba ◽  
Aline Cristina Velho ◽  
Mateus B. de Freitas ◽  
Maxime Holvoet ◽  
Alessandra Maia-Grondard ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Metabolic Cost ◽  
Allene Oxide ◽  
In Planta ◽  
Zymoseptoria Tritici ◽  
Oxidase Gene ◽  
Induce Resistance ◽  
Oxide Synthase ◽  
Related Proteins

The present study aimed to evaluate the potential of the laminarin-based formulation Vacciplant® to protect and induce resistance in wheat against Zymoseptoria tritici, a major pathogen on this crop. Under greenhouse conditions, a single foliar spraying of the product two days before inoculation with Z. tritici reduced disease severity and pycnidium density by 42% and 45%, respectively. Vacciplant® exhibited a direct antifungal activity on Z. tritici conidial germination both in vitro and in planta. Moreover, it reduced in planta substomatal colonization as well as pycnidium formation on treated leaves. Molecular investigations revealed that Vacciplant® elicits but did not prime the expression of several wheat genes related to defense pathways, including phenylpropanoids (phenylalanine ammonia-lyase and chalcone synthase), octadecanoids (lipoxygenase and allene oxide synthase), and pathogenesis‐related proteins (β‐1,3‐endoglucanase and chitinase). By contrast, it did not modulate the expression of oxalate oxidase gene involved in the reactive oxygen species metabolism. UHPLC-MS analysis indicated limited changes in leaf metabolome after product application in both non-inoculated and inoculated conditions, suggesting a low metabolic cost associated with induction of plant resistance. This study provides evidence that the laminarin-based formulation confers protection to wheat against Z. tritici through direct antifungal activity and elicitation of plant defense-associated genes.

scholarly journals Antifungal potency and modes of action of a novel olive tree defensin against closely related ascomycete fungal pathogens

2019 ◽  
Author(s):  
Hui Li ◽  
Siva L. S. Velivelli ◽  
Dilip M. Shah
Keyword(s):  
Antifungal Activity ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Olive Tree ◽  
In Planta ◽  
Core Motif ◽  
Antifungal Peptides ◽  
Cultivated Species ◽  
High Concentrations

AbstractAntimicrobial peptides play a pivotal role in the innate immunity of plants. Defensins are cysteine-rich antifungal peptides with multiple mechanisms of action (MOA). A novel Oleaceae-specific defensin gene family was discovered in the genome sequences of the wild and cultivated species of a perennial olive tree, Olea europaea. Antifungal properties of an olive tree defensin OefDef1.1 were investigated against a necrotrophic ascomycete fungal pathogen Botrytis cinerea in vitro and in planta. OefDef1.1 displayed potent antifungal activity against this pathogen by rapidly permeabilizing the plasma membrane of the conidial and germling cells. Interestingly, it was translocated to the cytoplasm and induced reactive oxygen species in the germlings, but not in the conidia. In medium containing high concentrations of Na1+, antifungal activity of OefDef1.1 against B. cinerea was significantly reduced. In contrast, OefDef1.1_V1 variant in which the γ-core motif of OefDef1.1 was replaced by that of a Medicago truncatula defensin MtDef4 displayed Na1+-tolerant antifungal activity and was more potent in reducing the virulence of B. cinerea in planta. OefDef1.1 also exhibited potent antifungal activity against three hemibiotrophic ascomycete pathogens Fusarium graminearum, F. oxysporum and F. virguliforme. Significant differences were observed among the four pathogens in their responses to OefDef1.1 in growth medium with or without the high concentrations of Na1+. The varied responses of closely related ascomycete pathogens to this defensin have implications for engineering disease resistance in plants.

scholarly journals Crinipellins A and I, Two Diterpenoids from the Basidiomycete Fungus Crinipellis rhizomaticola, as Potential Natural Fungicides

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2377 ◽  
Author(s):  
Jae Han ◽  
Mira Oh ◽  
Yu Lee ◽  
Jaehyuk Choi ◽  
Gyung Choi ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Ethyl Acetate ◽  
Culture Filtrate ◽  
Fungal Pathogens ◽  
Its Region ◽  
In Planta ◽  
Chemical Structures ◽  
Wide Range ◽  
Wheat Leaf

In the course of screening for microbes with antifungal activity, we found that the culture filtrate of the IUM00035 isolate exhibited strong antifungal activity against Magnaporthe oryzae and Colletotrichum coccodes in planta. Based on the phylogenetic analysis with the ITS region, the IUM00035 isolate was identified as Crinipellis rhizomaticola. To identify antifungal compounds from the C. rhizomaticola IUM00035 isolate, the culture filtrate of the isolate was partitioned with ethyl acetate and n-butanol and, consequently, two active compounds were isolated from the ethyl acetate extract. The chemical structures of the isolated compounds were determined as crinipellin A (1) and a new crinipellin derivative, crinipellin I (2), by NMR spectral analyses and a comparison of their NMR and MS data with those reported in the literature. Crinipellin A (1) exhibited a wide range of antifungal activity in vitro against C. coccodes, M. oryzae, Botrytis cinerea, and Phytophthora infestans (MICs = 1, 8, 31, and 31 µg/mL, respectively). Furthermore, when plants were treated with crinipellin A (1) (500 µg/mL) prior to inoculation with fungal pathogens, crinipellin A (1) exhibited disease control values of 88%, 65%, and 60% compared with non-treatment control against tomato late blight, pepper anthracnose, and wheat leaf rust, respectively. In contrast to crinipellin A (1), crinipellin I (2) showed weak or no activity (MICs > 250 µg/mL). Taken together, our results show that the C. rhizomaticola IUM00035 isolate suppresses the development of plant fungal diseases, in part through the production of crinipellin A (1).

scholarly journals IN VITRO SCREENING OF SIDEROPHORE-PRODUCERS FROM UPLAND RICE ROOT ENDOPHYTIC BACTERIA FOR ANTAGONISTIC ACTIVITIES AGAINST FUSARIUMOXYSPORUM, ANDXANTHOMONASORYZEA PV. ORYZAE

2020 ◽  
Vol 8 (12) ◽  
pp. 531-537
Author(s):  
Linh T. T. Ta ◽  
◽  
Nga T. P. Mai ◽  
Huong T. M. To ◽  
Chung D. Mai ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Antifungal Activity ◽  
Endophytic Bacteria ◽  
Plant Pathogens ◽  
Upland Rice ◽  
World Population ◽  
Moderate Activity ◽  
In Planta ◽  
The World

Rice is a staple crop for a large part of the world population including Vietnam. Although its export is ranged of second place over the world just after Thailand, rice production in Vietnam is challenging by various issues. The most significant is application of agrochemicals, which are not eco-friendly, leading to side effects on the ecosystem and human health. Endophytic bacteria (EB) possess different beneficial traits such as Plant Growth Promoting (PGP) and antagonistic activities against plant pathogens. In this study, a collection of 150 EB strains have been isolated from upland rice roots grown on the mountain-farm in the Tung village, Nam Co commune, Mu Cang Chai district, Yen Bai province, Vietnam. 119/150 isolates showed siderophoreproduction ability including 12 isolates showed the halo orange zone surrounding colonies of 1 – 10 mm in diameter (Dh), considering them as low level of siderophore production, 80 strains exhibited the moderate activity, Dh of 11 – 30 mm and 27 strains showed strong/high activity, Dh more than 30 mm. All 119 endophytic bacterial isolates were screened for antifungal activity against Fusariumoxysporum (Fo), and antibacterial activity against ​Xanthomonasoryzaepv.​oryzae (Xoo). Of them, thirty isolates showed either antifungal or antibacterial or both activities. Indeed, five isolates showed antifungal activity fifteen isolates exhibited the antibacterial activity. Especially, ten isolates named NC88, NC89, NC126, NC129, NC130, NC131, NC134, NC152, NC153, and NC156 showed antimicrobial activity against both tested pathogens. These results are the starting-up for further investigation in planta under conditions of net house and field trial in order to reveal the potential strains for the development of bioinoculants toward to control the diseases caused by Fo andXoo.

scholarly journals Analysis of the Indole Diterpene Gene Cluster for Biosynthesis of the Epoxy-Janthitrems in Epichloë Endophytes

2019 ◽  
Vol 7 (11) ◽  
pp. 560 ◽  
Author(s):  
Emma J. Ludlow ◽  
Simone Vassiliadis ◽  
Piyumi N. Ekanayake ◽  
Inoka K. Hettiarachchige ◽  
Priyanka Reddy ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Gene Cluster ◽  
Perennial Ryegrass ◽  
Biosynthetic Pathway ◽  
Whole Genome Sequence ◽  
In Planta ◽  
Biosynthesis Gene Cluster ◽  
Biosynthesis Gene ◽  
Lolitrem B ◽  
Epichloë Endophytes

Epoxy-janthitrems are a class of indole diterpenes with structural similarity to lolitrem B. Two taxa of asexual Epichloë endophytes have been reported to produce epoxy-janthitrems, LpTG-3 (Lolium perenne Taxonomic Group 3; e.g., NEA12) and LpTG-4 (e.g., E1). Epichloë epoxy-janthitrems are not well understood, the biosynthetic pathway and associated gene complement have not been described and while the literature suggests they are associated with superior protection against pasture insect pests and are tremorgenic in grazing mammals, these properties have not been confirmed using isolated and purified compounds. Whole genome sequence analysis was used to identify candidate genes for epoxy-janthitrem biosynthesis that are unique to epoxy-janthitrem producing strains of Epichloë. A gene, jtmD, was identified with homology to aromatic prenyl transferases involved in synthesis of indole diterpenes. The location of the epoxy-janthitrem biosynthesis gene cluster (JTM locus) was determined in the assembled nuclear genomes of NEA12 and E1. The JTM locus contains cluster 1 and cluster 2 of the lolitrem B biosynthesis gene cluster (LTM locus), as well as four genes jtmD, jtmO, jtm01, and jtm02 that are unique to Epichloë spp. that produce epoxy-janthitrems. Expression of each of the genes identified was confirmed using transcriptome analysis of perennial ryegrass-NEA12 and perennial ryegrass-E1 symbiota. Sequence analysis confirmed the genes are functionally similar to those involved in biosynthesis of related indole diterpene compounds. RNAi silencing of jtmD and in planta assessment in host-endophyte associations confirms the role of jtmD in epoxy-janthitrem production. Using LCMS/MS technologies, a biosynthetic pathway for the production of epoxy-janthitrems I–IV in Epichloë endophytes is proposed.

Antifungal activity and biological characteristics of the novel fungicide quinofumelin against Sclerotinia sclerotiorum

Plant Disease ◽  
2021 ◽  
Author(s):  
Xian Tao ◽  
Huahua Zhao ◽  
Haorong Xu ◽  
Zhongke Li ◽  
Jian-Xin Wang ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Sclerotinia Sclerotiorum ◽  
Plant Pathogens ◽  
Cross Resistance ◽  
Broad Host Range ◽  
In Planta ◽  
Control Efficacy ◽  
Worldwide Distribution ◽  
Chemical Fungicides

Sclerotinia sclerotiorum is a devastating plant pathogen with a broad host range and worldwide distribution. The application of chemical fungicides is a primary strategy for controlling this pathogen. However, under the high selective pressure of chemical fungicides, fungicide resistance has emerged and gradually increased, resulting in the failure to control S. sclerotiorum in the field. Quinofumelin is a novel quinoline fungicide, but its antifungal activities against plant pathogens have been rarely reported. Here, we determined the antifungal activity of quinofumelin against S. sclerotiorum in vitro and in planta. The EC50 values ranged from 0.0004 to 0.0059 μg mL-1 with a mean EC50 of 0.0017 ± 0.0009 μg mL-1 and were normally distributed (P=0.402). In addition, no cross-resistance was observed between quinofumelin and other fungicides, dimethachlone, boscalid, or carbendazim, which are commonly used to manage S. sclerotiorum. Quinofumelin did not affect glycerol and oxalic acid production of either carbendazim-sensitive or -resistant isolates. Moreover, quinofumelin exhibited excellent protective, curative, and translaminar activity against S. sclerotiorum on oilseed rape leaves. Protective activity was higher than curative activity. Interestingly, quinofumelin inhibited the formation of the infection cushion in S. sclerotiorum, which may contribute to the control efficacy of quinofumelin against S. sclerotiorum in the field. Our findings indicate that quinofumelin has excellent control efficacy against S. sclerotiorum in vitro and in planta as compared with the currently extensively used fungicides and could be used to manage carbendazim- and dimethachlone-resistance in S. sclerotiorum in the field.

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