Control Of Plant Pathogenic Fungi Research Articles

Resistance-Related l-Pyroglutamic Acid Affects the Biosynthesis of Trichothecenes and Phenylpropanoids by F. graminearum Sensu Stricto.

Fungicide application remains amongst the most widely used methods of fungal control in agroecosystems. However, the extensive use of fungicides poses hazards to human health and the natural environment and does not always ensure the effective decrease of mycotoxins in food and feed. Nowadays, the rising threat from mycotoxin contamination of staple foods has stimulated efforts in developing alternative strategies to control plant pathogenic fungi. A substantial effort is focused on the identification of plant-derived compounds inhibiting mycotoxin production by plant pathogenic fungi. l-Pyroglutamic acid has recently been suggested as playing a role in the response of barley to toxigenic Fusaria. Considering the above, we studied the response of various strains of F. graminearum sensu stricto to different levels of l-pyroglutamic acid on solid YES (yeast extract sucrose) media. l-Pyroglutamic acid decreased the accumulation of trichothecenes in all examined strains. Gene expression studies addressing Tri genes (Tri4, Tri5, and Tri10), which induce the biosynthesis of trichothecenes, revealed the production of mycotoxins by l-pyroglutamic acid to be inhibited at the transcriptional level. Besides inhibitory effects on mycotoxin production, l-pyroglutamic acid exhibited variable and concentration-related effects on phenylpropanoid production by fungi. Accumulation of most of the fungal-derived phenolic acids decreased in the presence of 100 and 400 µg/g of l-pyroglutamic acid. However, a higher dose (800 µg/g) of l-pyroglutamic acid increased the accumulation of trans-cinnamic acid in the media. The accumulation of fungal-derived naringenin increased in the presence of l-pyroglutamic acid. Contrasting results were obtained for quercetin, apigenin, luteolin, and kaempferol, the accumulation of which decreased in the samples treated with 100 and 400 µg/g of l-pyroglutamic acid, whereas the highest l-pyroglutamic acid concentration (800 µg/g) seemed to induce their biosynthesis. The results obtained in this study provide new insights for breeders involved in studies on resistance against Fusaria.

Inhibition of Fusarium oxysporum by AgNPs biosynthesised using Cinnamomum camphora fruit extract.

Cinnamomum camphora fruit extract was used to biosynthesise silver nanoparticles (AgNPs), and the optimised synthesis system was ascertained through solution colour change and ultraviolet-visible absorption spectra. It contained 20 ml of fruit extract, 4 mM Ag nitrate, and pH 7. AgNPs obtained based on such conditions were spherical and finely dispersed, with an average size of 20.3 nm. As-synthesised AgNPs exhibited excellent antifungal effect against Fusarium oxysporum. At a dose of 400 μg/ml of AgNPs, the inhibition rate of colony growth reached 61.00% and an IC50 value of 154.39 μg/ml. In addition, the conidia germination was totally inhibited at 100 μg/ml of AgNPs. Results of this study provide a new approach for biological control of plant pathogenic fungi, and it makes that possible for developing a brand new fungistat.

In vitro Potential of Aqueous Extracts of Plant Leaves to inhibit Pathogenic Fungi

The in vitro potential of aqueous extracts of plant leaves to inhibit pathogenic fungi was carried out. The effect of leaf extract and concentration on growth inhibition of organism I (Aspergillus flavus) in vitro revealed that a concentration of 100g/mL, Moringa oleifera leaf extract (MLE) gave the highest growth inhibition of (59.14) followed by Neem (Azadirachta indica) leaf extract (NLE) (49.70) and Bitter leaf (Vernonia amygdalina) extract (BLE) (45.84) respectively while the least growth inhibition on organism 1 (Aspergillus flavus) was by MLE at concentration of 40 g/mL (30.11) followed by NLE at 60 g/mL (32.11) and BLE at 40 g/mL (40.13). On organism 2 (Penicillium waksmanii), MLE at a concentration of 100 g/mL gave the highest growth inhibition of (50.49) followed by NLE (49.01) and BLE (36.72) respectively while the least inhibition on growth of organism 2 in vitro was by BLE at concentration of 60 g/mL (16.05) followed by MLE (40.70) and NLE (40.70) at concentration of 80 g/mL respectively. On organism 3 (Botryodiplodia theobromae), MLE at concentration of 100 g/mL gave the highest inhibition of growth (57.00) followed by NLE (52.71) and BLE (50.15) respectively while the least inhibition on growth of organism 3 in vitro was by BLE at 40 g/mL (21.50) followed by MLE at 60 g/mL (31.06) and NLE at 40 g/mL (41.89). On organism 4 (Fusarium oxysporum), the highest growth inhibition was by MLE at 100g/mL (54.02) followed by NLE at 100 g/mL (49.62) and BLE at 100 g/mL (44.41) while MLE showed the least growth inhibition at 60 g/mL (24.04) followed by BLE at 40 g/mL (26.60) and NLE at 40 g/mL (30.12). NLE showed the highest grand inhibitory effect of extract concentration on growth inhibition of organism 5 (Colletotrichum asianum) in vitro at 100 g/mL (53.68) followed by MLE at 100 g/mL (51.51) and BLE at 100 g/mL (40.94). The least inhibitory effect on the growth of organism 5 in vitro was by BLE at 80 g/mL (21.26) followed by NLE at 40 g/mL (22.25) and MLE at 40 g/mL (32.69). The controls ranged from 2.23 to 4.31 across all extract concentrations and fungal isolates. There were significant differences in growth inhibition between extract concentrations and their controls on all fungal isolates. The use of plant extracts provides alternative means for controlling plant pathogenic fungi.

BIOASSAY OF BOTANICAL OILS AGAINST ALTERNARIA SOLANI

Objective: In vitro antifungal activity of six essential oils of 1. Ocimum tenuiflorum (Purple leaves/Krishna Tulsi) 2. Cymbopogon citrates (Nimbu ghas), 3. Origanum majorina (Sweet majoram), 4. Ocimum citriodorum (Nimbu tulsi), 5. Ocimum bascillicum (Gulal tulsi), and 6. Ocimum sanctum (Green leaves/Shree tulsi) were investigated against economically important phytopathogenic fungi, Alternaria solani, isolated from infected chilly. Methods: The experiment was carried out by Whatman paper disc method using Whatman paper No.3 on Potato Dextrose Agar with three replicates. Five concentrations of each essential oils i.e., 20, 40, 60, 80 and 100% were assayed against the test fungus. The experiment was carried out at 27ᵒC and mycelial growth was measured after every third day, upto 15 d using statistical method.Results: It is an evident from this study that all the oils used in this study are inhibiting test fungi, oil of O. bascillicum and O. sanctum are completely (100%) inhibiting test fungi.Conclusion: It may be concluded from the above study that all the taken oils have a good potential to control plant pathogenic fungi and these could be considered for developing a new fungicide.

The mycoparasitic fungus Clonostachys rosea responds with both common and specific gene expression during interspecific interactions with fungal prey.

Clonostachys rosea is a necrotrophic mycoparasitic fungus, used for biological control of plant pathogenic fungi. A better understanding of the underlying mechanisms resulting in successful biocontrol is important for knowledge‐based improvements of the application and use of biocontrol in agricultural production systems. Transcriptomic analyses revealed that C. rosea responded with both common and specific gene expression during interactions with the fungal prey species Botrytis cinerea and Fusarium graminearum. Genes predicted to encode proteins involved in membrane transport, biosynthesis of secondary metabolites and carbohydrate‐active enzymes were induced during the mycoparasitic attack. Predicted major facilitator superfamily (MFS) transporters constituted 54% of the induced genes, and detailed phylogenetic and evolutionary analyses showed that a majority of these genes belonged to MFS gene families evolving under selection for increased paralog numbers, with predicted functions in drug resistance and transport of carbohydrates and small organic compounds. Sequence analysis of MFS transporters from family 2.A.1.3.65 identified rapidly evolving loop regions forming the entry to the transport tunnel, indicating changes in substrate specificity as a target for selection. Deletion of the MFS transporter gene mfs464 resulted in mutants with increased growth inhibitory activity against F. graminearum, providing evidence for a function in interspecific fungal interactions. In summary, we show that the mycoparasite C. rosea can distinguish between fungal prey species and modulate its transcriptomic responses accordingly. Gene expression data emphasize the importance of secondary metabolites in mycoparasitic interactions.

LC-MS/MS Tandem Mass Spectrometry for Analysis of Phenolic Compounds and Pentacyclic Triterpenes in Antifungal Extracts of Terminalia brownii (Fresen).

Decoctions and macerations of the stem bark and wood of Terminalia brownii Fresen. are used in traditional medicine for fungal infections and as fungicides on field crops and in traditional granaries in Sudan. In addition, T. brownii water extracts are commonly used as sprays for protecting wooden houses and furniture. Therefore, using agar disc diffusion and macrodilution methods, eight extracts of various polarities from the stem wood and bark were screened for their growth-inhibitory effects against filamentous fungi commonly causing fruit, vegetable, grain and wood decay, as well as infections in the immunocompromised host. Ethyl acetate extracts of the stem wood and bark gave the best antifungal activities, with MIC values of 250 µg/mL against Nattrassia mangiferae and Fusarium verticillioides, and 500 µg/mL against Aspergillus niger and Aspergillus flavus. Aqueous extracts gave almost as potent effects as the ethyl acetate extracts against the Aspergillus and Fusarium strains, and were slightly more active than the ethyl acetate extracts against Nattrassia mangiferae. Thin layer chromatography, RP-HPLC-DAD and tandem mass spectrometry (LC-MS/MS), were employed to identify the chemical constituents in the ethyl acetate fractions of the stem bark and wood. The stem bark and wood were found to have a similar qualitative composition of polyphenols and triterpenoids, but differed quantitatively from each other. The stilbene derivatives, cis- (3) and trans- resveratrol-3-O-β-galloylglucoside (4), were identified for the first time in T. brownii. Moreover, methyl-(S)-flavogallonate (5), quercetin-7-β-O-di-glucoside (8), quercetin-7-O-galloyl-glucoside (10), naringenin-4′-methoxy-7-pyranoside (7), 5,6-dihydroxy-3′,4′,7-tri-methoxy flavone (12), gallagic acid dilactone (terminalin) (6), a corilagin derivative (9) and two oleanane type triterpenoids (1) and (2) were characterized. The flavonoids, a corilagin derivative and terminalin, have not been identified before in T. brownii. We reported earlier on the occurrence of methyl-S-flavogallonate and its isomer in the roots of T. brownii, but this is the first report on their occurrence in the stem wood as well. Our results justify the traditional uses of macerations and decoctions of T. brownii stem wood and bark for crop and wood protection and demonstrate that standardized extracts could have uses for the eco-friendly control of plant pathogenic fungi in African agroforestry systems. Likewise, our results justify the traditional uses of these preparations for the treatment of skin infections caused by filamentous fungi.

RNAi as an emerging approach to control Fusarium head blight disease and mycotoxin contamination in cereals.

Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host‐induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double‐stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi‐mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Antifungal effect of green synthesised silver nanoparticles against Setosphaeria turcica

Green synthesis of silver nanoparticles (AgNPs) is an interesting issue of the nanoscience and nanotechnology due to their unique properties. In the present study, Ginkgo biloba L. leaf extract was used to synthesise AgNPs. The effects of quantity of leaves, concentration of Ag nitrate (AgNO3), reaction temperature, and pH were studied to discover the optimal synthesis system. In addition, antifungal effect of AgNPs against Setosphaeria turcica was measured through inhibition zone method. The optimal biosynthesis system contained 15 g of leaf, 8 mM AgNO3, and 80°C at pH 9.0. Under mentioned conditions, the resulting synthesised NPs were nearly spherical, with an average size of 14 nm. In tests, AgNPs synthesised at different pH resulted in different inhibition zones, diameters increased gradually at pH from 3.0 to 11.0, while antifungal effect reached maximum at 9.0. Results of this study offer a new approach for biological control plant pathogenic fungi, and it has potential application for screening novel fungistats with high efficiency and low toxicity.

Biological characterization of fenpicoxamid, a new fungicide with utility in cereals and other crops.

BACKGROUNDThe development of novel highly efficacious fungicides that lack cross‐resistance is extremely desirable. Fenpicoxamid (Inatreq™ active) possesses these characteristics and is a member of a novel picolinamide class of fungicides derived from the antifungal natural product UK‐2A.RESULTSFenpicoxamid strongly inhibited in vitro growth of several ascomycete fungi, including Zymoseptoria tritici (EC50, 0.051 mg L−1). Fenpicoxamid is converted by Z. tritici to UK‐2A, a 15‐fold stronger inhibitor of Z. tritici growth (EC50, 0.0033 mg L−1). Strong fungicidal activity of fenpicoxamid against driver cereal diseases was confirmed in greenhouse tests, where activity on Z. tritici and Puccinia triticina matched that of fluxapyroxad. Due to its novel target site (Qi site of the respiratory cyt bc1 complex) for the cereals market, fenpicoxamid is not cross‐resistant to Z. tritici isolates resistant to strobilurin and/or azole fungicides. Across multiple European field trials Z. tritici was strongly controlled (mean, 82%) by 100 g as ha−1 applications of fenpicoxamid, which demonstrated excellent residual activity.CONCLUSIONSThe novel chemistry and biochemical target site of fenpicoxamid as well as its lack of cross‐resistance and strong efficacy against Z. tritici and other pathogens highlight the importance of fenpicoxamid as a new tool for controlling plant pathogenic fungi. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Collembolans and soil nematodes as biological regulators of the plant pathogen Fusarium culmorum

A field study was conducted to investigate biocontrol and interaction effects of important members (Folsomia candida, Collembola, and Aphelenchoides saprophilus, Nematoda) of the soil food web on the plant pathogenic fungus Fusarium culmorum in wheat straw. The soil fauna was introduced in minicontainers in different numbers and combinations and exposed to either Fusarium-infected or non-infected wheat straw. Minicontainers were established in the topsoil of a winter wheat field after harvest. After 2 and 4 weeks, biomass of F. culmorum was detected in samples of soil and wheat straw using double antibody sandwich (DAS) ELISA method. Furthermore, individual density of collembolans and nematodes was determined. The content of Fusarium biomass was reduced significantly throughout all treatments after 2 weeks. After 4 weeks of minicontainer exposure, Fusarium biomass decreased significantly in treatments containing collembolans and nematodes in single culture compared to the control. The results demonstrate the potential of collembolans and nematodes as biological regulators. Furthermore, the introduced soil fauna contributes to a sustainable control of fungal plant pathogens in wheat straw, thus reducing the risk of plant diseases as an important ecosystem service for soil health.

Isolation and identification of a cold-adapted bacterium and its characterization for biocontrol and plant growth-promoting activity

As a consequence of the importance of crop cultivation in Bioregenerative Life Support System (BLSS), there is a necessity of protecting the plants from pathogenic diseases. Cave soil bacteria can be utilized as a source for isolating biocontrol bacteria that are suitable for plant growth in BLSS. Pseudochrobactrum kiredjianiae strain A4 (GenBank accession KT203923) is a gram-positive, short-rod shaped and whitish bacterium isolated from cave soil, and is culturable at 13°C. A species-level identification was conducted by 16S rRNA gene sequencing, which showed that this strain had a 98% similarity with sequences of P. kiredjianiae isolated from the public domain. The A4 strain was positive for siderophore, indole-3-acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. The results of in vitro experiments showed that A4 could inhibit the growth and development of Rhizoctonia cerealis, Fusarium graminearumt, Magnaporthe grisea, Fusarium oxysporum and Botrytis cinerea. Under greenhouse conditions, the bacterium A4 improved the physiological parameters and reduced the defense enzymes activities of wheat (Triticum aestivum L.) in the presence of R. cerealis. Statistical analysis of measured parameters revealed that A4-inoculated wheat plants were positively alleviating pathogenic stress. These results indicate that the isolate A4 provides a promising solution to control plant pathogenic fungi in BLSS.

Antifungal potential of Corallococcus sp. strain EGB against plant pathogenic fungi

Antifungal microorganisms have play an important role in the biological control of plant fungal pathogens. In this study, strain EGB, which was identified as a Corallococcus sp. with excellent antifungal activity, was selected as a biocontrol agent against phytopathogenic fungi from 41 myxobacterial isolates in previous research. Efficient biocontrol activity of Corallococcus sp. EGB was observed on plate assays and pot experiments. Corallococcus sp. strain EGB exhibited efficient biological control of Fusarium oxysporum, significantly decreasing the incidence of Fusarium wilt to 7.7% and the disease severity from 61.2% to 7.5%. Microscopic observations of hyphae as well as periodate oxidation analysis and HPLC analysis of the oligosaccharides released from yeast cell wall treated with crude enzymes preparation from Corallococcus sp. strain EGB revealed that a β-1,6-glucanase might be involved in the antifungal mechanism. Such results differ from previews reports primarily attributing the antifungal activity of myxobacteria to secondary metabolites. Our study highlights Corallococcus sp. strain EGB as a novel type of biocontrol agent, which may have potential application in the control of plant pathogenic fungi.

Antifungal Effects of Foeniculum vulgare Mill. Herb Essential Oil on the Phenotypical Characterizations of Alternaria alternata Kessel.

The fungitoxicity of Foeniculum vulgare herb essential oil was evaluated by mycelial growth inhibition assessment in medium culture. The radial growth of the Alternaria alternata was completely inhibited at the oil levels of 500 and 300 ppm in poisoned food and volatile activity assessments, respectively. Microscopic observations using Light Microscope showed morphogenic changes in the test fungus with 300 ppm of the oil. These changes included a significant loss of conidiation, decrease hyphal diameter and induce cytoplasm condensation. The treatment with the oil also resulted in a highly lobate and bulbous anomalous structure on the hyphal tips. Essential oil of F. vulgare at 500 ppm effectively reduced the percentage of rotted tomatoes in in vivo. Gas chromatography-mass spectrometry analysis of the Fennel oil revealed that it was considered of 25 monoterpenoid compounds of which trans-anethole, estragole, and fenchone as the major components. Findings of the current study suggest that essential oils have natural phytochemical and could be used as a substitute bioactive compounds for chemicals in control of plant pathogenic fungi on fruits or vegetables.

Shelf Life of Trichoderma Harzianum an Antagonist in Different Oil Based Formulations

<div><p><em>Trichoderma</em><em> is a promising candidate for the biological control of plant pathogenic fungi. While planning the application of antagonistic Trichoderma strains for the purposes of biological control, it is very important to consider the environmental parameters affecting the bio-control agents in the soil. A series of abiotic and biotic environmental parameters has an influence on the bio-control efficacy of Trichoderma. The major bottleneck of bio-pesticides is the shelf life and inconsistent performance. In order to overcome this problem, the present study the liquid formulation was used to increase the shelf life of Trichoderma. Oils like Canole oil, paraffin oil, soya bean oil, Neem oil and Glycerol and their combination of paraffin oil and glycerol, paraffin oil and Soya bean oil, Canola oil and Glycerol, and Paraffin oil and Neem oil were used, among which Canola oil + Glycerol based formulation and Paraffin oil based formulation with 3.00 x 104 Cfu/ml and 2.00 X 104 Cfu/ml viable conidia showed extended shelf life of twelve months of storage.</em></p></div>

Competition assays and physiological experiments of soil and phyllosphere yeasts identify Candida subhashii as a novel antagonist of filamentous fungi

BackgroundWhile recent advances in next generation sequencing technologies have enabled researchers to readily identify countless microbial species in soil, rhizosphere, and phyllosphere microbiomes, the biological functions of the majority of these species are unknown. Functional studies are therefore urgently needed in order to characterize the plethora of microorganisms that are being identified and to point out species that may be used for biotechnology or plant protection. Here, we used a dual culture assay and growth analyses to characterise yeasts (40 different isolates) and their antagonistic effect on 16 filamentous fungi; comprising plant pathogens, antagonists, and saprophytes.ResultsOverall, this competition screen of 640 pairwise combinations revealed a broad range of outcomes, ranging from small stimulatory effects of some yeasts up to a growth inhibition of more than 80% by individual species. On average, yeasts isolated from soil suppressed filamentous fungi more strongly than phyllosphere yeasts and the antagonistic activity was a species-/isolate-specific property and not dependent on the filamentous fungus a yeast was interacting with. The isolates with the strongest antagonistic activity were Metschnikowia pulcherrima, Hanseniaspora sp., Cyberlindnera sargentensis, Aureobasidium pullulans, Candida subhashii, and Pichia kluyveri. Among these, the soil yeasts (C. sargentensis, A. pullulans, C. subhashii) assimilated and/or oxidized more di-, tri- and tetrasaccharides and organic acids than yeasts from the phyllosphere. Only the two yeasts C. subhashii and M. pulcherrima were able to grow with N-acetyl-glucosamine as carbon source.ConclusionsThe competition assays and physiological experiments described here identified known antagonists that have been implicated in the biological control of plant pathogenic fungi in the past, but also little characterised species such as C. subhashii. Overall, soil yeasts were more antagonistic and metabolically versatile than yeasts from the phyllosphere. Noteworthy was the strong antagonistic activity of the soil yeast C. subhashii, which had so far only been described from a clinical sample and not been studied with respect to biocontrol. Based on binary competition assays and growth analyses (e.g., on different carbon sources, growth in root exudates), C. subhashii was identified as a competitive and antagonistic soil yeast with potential as a novel biocontrol agent against plant pathogenic fungi.

Pathogen inactivation of cruciferous phytoalexins: detoxification reactions, enzymes and inhibitors

This review covers the detoxification pathways of cruciferous phytoalexins, the corresponding detoxifying enzymes and their natural and synthetic inhibitors. Paldoxins are examined as a potentially sustainable strategy to control plant pathogenic fungi.

Antifungal Activity of Pseudomonas frederiksbergensis CMAA 1323 Isolated from the Antarctic Hair Grass Deschampsia antarctica

Aims: Epiphytic bacteria, isolated from Deschampsia antarctica, were screened for their potential to inhibit the plant pathogen Botrytis cinerea, the causal agent of gray mold disease of strawberry pseudofruits. This phytopathogenic fungus is more active and the disease is more serious in temperate climate where the temperatures are lower. Methodology: The approach involved the isolation and characterization of bacteria from the phyllosphere of D. antarctica and the evaluation of their antifungal activity. Results: A total of 56 bacterial strains were isolated and only one of them, identified by the sequencing of 16S rDNA gene, as Pseudomonas frederiksbergensis CMAA 1323, inhibited the mycelial growth and the conidial germination of the fungus. Its ethyl acetate extract also inhibited Original Research Article Melo et al.; BMRJ, 14(3): 1-11, 2016; Article no.BMRJ.25314 2 the mycelial growth. Analysis of the bioactive fraction by using liquid chromatography coupled to a mass spectrometry (LC-MS) revealed the presence of cyclo(Pro-Val), a compound belonging to the class of diketopiperazines (DKPs). Conclusion: These findings support the potential use of the psychrophilic bacterium P. frederiksbergensis as promising antifungal agent, and highlight the need for more studies with this bacterium in the biological control of plant pathogenic fungi.

Antifungal potential and phytochemistry of Tetrapterys multiglandulosa CAV aerial parts

Tetrapterys spp. are considered toxic to grazing animals owing to the presence of a poisonous constituent cardiotonic glycoside. However, other chemicals within the plant have allelopathic, bactericidal, and fungicidal activities. The objective of this study was to search for natural products as alternatives in the control of plant pathogenic fungi, which diminish the crop productivity and cause damage to animal and human health. The phytochemical content of the stems and leaves was investigated alongside the fungitoxic potential of aqueous and ethanol extracts from aerial parts of T. multiglandulosa on Fusarium moniliforme and F. graminearum . The leaves and stems were obtained from 20 arrays of T. multiglandulosa from Bataypora City, south of Mato Grosso do Sul, and classified as young and mature. The botanical material was oven dried, crushed, and its aqueous and 20% ethanol extracts were used for qualitative and quantitative phytochemical assays. For in vitro tests of fungal growth inhibition, extract concentrations of 200, 400, 800, 1600, and 2000 μg L -1 were assayed, with two control groups. Phytochemical tests from aqueous and ethanol extracts of young and mature leaves indicated the presence of phenolic compounds, tannins, flavonoids, saponins, alkaloids, and cardiotonic glycosides. The aqueous extract of young leaves showed potential fungicidal activity against F. graminearum, with values ranging from 21.25% to 33.53% colony growth inhibition.

Gliotoxin--bane or boon?

Gliotoxin (GT) is the most important epidithiodioxopiperazine (ETP)-type fungal toxin. GT was originally isolated from Trichoderma species as an antibiotic substance involved in biological control of plant pathogenic fungi. A few isolates of GT-producing Trichoderma virens are commercially marketed for biological control and widely used in agriculture. Furthermore, GT is long known as an immunosuppressive agent and also reported to have anti-tumour properties. However, recent publications suggest that GT is a virulence determinant of the human pathogen Aspergillus fumigatus. This compound is thus important on several counts - it has medicinal properties, is a pathogenicity determinant, is a potential diagnostic marker and is important in biological crop protection. The present article addresses this paradox and the ecological role of GT. We discuss the function of GT as defence molecule, the role in aspergillosis and suggest solutions for safe application of Trichoderma-based biofungicides.

Volatiles from white-rot fungi for controlling plant pathogenic fungi

Fungal volatile secondary metabolites play important roles in mediating antagonistic and beneficial interactions among organisms. The effects of eight strains of white-rot fungi cultured on potato waste against the mycelial growth of Botrytis cinerea, Fusarium oxysporum and Mucor miehei were investigated using a bi-compartmented Petri dish assay. The chemical composition of volatile organic compounds released from the strain with the highest inhibitory effect was also investigated by headspace solid-phase microextraction and gas chromatography/mass spectrometry analysis. Of the eight white-rot fungi evaluated, Anthracophyllum discolor. Sp4 showed a high inhibitory activity against M. miehei (approximately 76%) and B. cinerea (approximately 20%). F. oxysporum was inhibited to a lesser extent (approximately 10%) by A. discolor and T. versiscolor. The gas chromatography/mass spectrometry analysis showed nine main volatile compounds released from A. discolor Sp4, among them are the sesquiterpenesα-bisabolene and bulnesene, and the chlorinated aromatic compounds 1,5-dichloro-2,3-dimethoxybenzene, 3,5-dichloro-4-methoxybenzaldehyde and 3-chloro-4-methoxybenzaldehyde. Some of which have been reported previously with antimicrobial activity. The antifungal activity and volatile profile of A. discolor have not been previously reported.