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Showing papers on "Mycelium published in 2009"


Journal ArticleDOI
TL;DR: Evidence of a plant AMT that is involved in N uptake during mycorrhiza symbiosis is offered and the results suggest that the transporter binds charged ammonium in the apoplastic interfacial compartment and releases the uncharged NH3 into the plant cytoplasm.
Abstract: In mycorrhizal associations, the fungal partner assists its plant host by providing nitrogen (N) in addition to phosphate. Arbuscular mycorrhizal (AM) fungi have access to inorganic or organic forms of N and translocate them via arginine from the extra- to the intraradical mycelium, where the N is transferred to the plant without any carbon skeleton. However, the molecular form in which N is transferred, as well as the involved mechanisms, is still under debate. NH(4)(+) seems to be the preferential transferred molecule, but no plant ammonium transporter (AMT) has been identified so far. Here, we offer evidence of a plant AMT that is involved in N uptake during mycorrhiza symbiosis. The gene LjAMT2;2, which has been shown to be the highest up-regulated gene in a transcriptomic analysis of Lotus japonicus roots upon colonization with Gigaspora margarita, has been characterized as a high-affinity AMT belonging to the AMT2 subfamily. It is exclusively expressed in the mycorrhizal roots, but not in the nodules, and transcripts have preferentially been located in the arbusculated cells. Yeast (Saccharomyces cerevisiae) mutant complementation has confirmed its functionality and revealed its dependency on acidic pH. The transport experiments using Xenopus laevis oocytes indicated that, unlike other plant AMTs, LjAMT2;2 transports NH(3) instead of NH(4)(+). Our results suggest that the transporter binds charged ammonium in the apoplastic interfacial compartment and releases the uncharged NH(3) into the plant cytoplasm. The implications of such a finding are discussed in the context of AM functioning and plant phosphorus uptake.

302 citations


Journal ArticleDOI
TL;DR: Results establish the central role of IAA and ethylene as signal molecules in truffle/plant interactions and demonstrate that truffles synthesize ethylene from l-methionine probably through the α-keto-γ-(methylthio)butyric acid pathway.
Abstract: Truffles are symbiotic fungi that form ectomycorrhizas with plant roots. Here we present evidence that at an early stage of the interaction, i.e. prior to physical contact, mycelia of the white truffle Tuber borchii and the black truffle Tuber melanopsorum induce alterations in root morphology of the host Cistus incanus and the nonhost Arabidopsis (Arabidopsis thaliana; i.e. primary root shortening, lateral root formation, root hair stimulation). This was most likely due to the production of indole-3-acetic acid (IAA) and ethylene by the mycelium. Application of a mixture of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and IAA fully mimicked the root morphology induced by the mycelium for both host and nonhost plants. Application of the single hormones only partially mimicked it. Furthermore, primary root growth was not inhibited in the Arabidopsis auxin transport mutant aux1-7 by truffle metabolites while root branching was less effected in the ethylene-insensitive mutant ein2-LH. The double mutant aux1-7;ein2-LH displayed reduced sensitivity to fungus-induced primary root shortening and branching. In agreement with the signaling nature of truffle metabolites, increased expression of the auxin response reporter DR5∷GFP in Arabidopsis root meristems subjected to the mycelium could be observed, confirming that truffles modify the endogenous hormonal balance of plants. Last, we demonstrate that truffles synthesize ethylene from l-methionine probably through the α-keto-γ-(methylthio)butyric acid pathway. Taken together, these results establish the central role of IAA and ethylene as signal molecules in truffle/plant interactions.

164 citations


Journal ArticleDOI
R. W. Rees1, J. Flood2, Y. Hasan, Ursula Potter1, Richard M. Cooper1 
TL;DR: In this article, a reproducible infection of intact roots of oil palm (Elaeis guineensis) with Ganoderma boninense, the cause of basal stem rot, showed penetration followed by rapid longitudinal progression of hyphae and colonization of the lower stem.
Abstract: Reproducible infection of intact roots of oil palm (Elaeis guineensis) with Ganoderma boninense, the cause of basal stem rot, showed penetration followed by rapid longitudinal progression of hyphae and colonization of the lower stem (bole) Light and transmission electron microscopy showed invasion of the root cortex, with no evidence of selective progression through the vascular system or lacunae In newly colonized tissue the fungus behaved as a hemibiotroph, with numerous, wide, intracellular hyphae occupying entire host cells that possessed intact cell walls and contained discernible cytoplasm and organelles In the bole this phase coincided with a complete depletion of previously abundant starch grains in advance of invasion Subsequently, in the roots and colonized stem base, widespread necrotrophic, enzymatic attack of all layers of the host cell walls occurred Hyphae were intra- and intercellular and intramural and associated host cell wall degradation was often at a distance from hyphae, resulting in cavities within cell walls A third developmental stage was the formation of an extensive, melanized, tough mycelium or pseudo-sclerotium which surrounded roots and comprised many very thick-walled cells encasing more typical thin-walled hyphae Macroscopic observation of and isolation from the bole of randomly felled, commercial palms provided confirmatory evidence that multiple infections originated in the roots before spreading into the base of long-established palms

131 citations


Journal ArticleDOI
TL;DR: A positive correlation was found between the total mycelia, the number of tips and the volumetric enzyme productivity, indicating the weight of these variables on the enzyme productivity.

127 citations


Journal ArticleDOI
TL;DR: The results presented indicate that the endophytic strain E1R-j of B. subtilis meets demands required for biocontrol of take-all and effectively retarded infection and colonization of Ggt in root tissue.

125 citations


Journal ArticleDOI
TL;DR: The hypothesis that fungal networks facilitate the movement of bacteria by providing continuous liquid films in which gradients of chemoattractants can form and chemotactic swimming can take place suggests that fungi improve the accessibility of contaminants in water-unsaturated environments.
Abstract: Contaminant biodegradation in soil is frequently limited by hindered physical access of bacteria to the contaminants. In the frame of the development of novel bioremediation approaches based on ecological principles, we tested the hypothesis that fungal networks facilitate the movement of bacteria by providing continuous liquid films in which gradients of chemoattractants can form and chemotactic swimming can take place. Unlike bacteria, filamentous fungi spread with ease in water-unsaturated soil. In a simple laboratory model of a water-unsaturated environment, we studied the movement of polycyclic aromatic hydrocarbon-degrading Pseudomonas putida PpG7 (NAH7) along a mycelium of Pythium ultimum. Some undirected dispersal was observed in the absence of a chemoattractant or when the non-chemotactic derivative strain P. putida G7.C1 (pHG100) was used. The bacterial movement became fourfold more effective and clearly directed when the chemotactic wild type was used and salicylate was present as a chemoattractant. No dispersal of bacteria was found in the absence of the fungus. These findings point at a role of mycelia for the translocation of chemicals and microorganisms. The results suggest that fungi improve the accessibility of contaminants in water-unsaturated environments.

121 citations


Journal ArticleDOI
TL;DR: In this paper, a three-level Box-Behnken design combined with the canonical and ridge analyses was employed to optimise the process parameters for polysaccharide extraction from cultured mycelium of Cordyceps sinensis, one of the most valued traditional Chinese medicines and health foods.

119 citations


Journal ArticleDOI
TL;DR: From experiments in different colonized host roots growing under several environmental conditions, it seems that GintAQP1 gene expression is regulated in a compensatory way regarding host root aquaporin expression, which could be involved in the transport of water from osmotically favorable growing mycelium or host roots to salt-stressed tissues.
Abstract: Roots of most plants in nature are colonized by arbuscular mycorrhizal (AM) fungi. Among the beneficial effects of this symbiosis to the host plant is the transport of water by the AM mycelium from inaccessible soil water resources to host roots. Here, an aquaporin (water channel) gene from an AM fungus (Glomus intraradices), which was named GintAQP1, is reported for the first time. From experiments in different colonized host roots growing under several environmental conditions, it seems that GintAQP1 gene expression is regulated in a compensatory way regarding host root aquaporin expression. At the same time, from in vitro experiments, it was shown that a signaling communication between NaCl-treated mycelium and untreated mycelium took place in order to regulate gene expression of both GintAQP1 and host root aquaporins. This communication could be involved in the transport of water from osmotically favorable growing mycelium or host roots to salt-stressed tissues.

107 citations


Journal ArticleDOI
TL;DR: Results indicate that PUFA biosynthesis is favored in young, fast growing mycelia, while it decreases significantly in aged mycelio, and when M. isabellina was grown on pear pomace, an agro-industrial waste.

97 citations


Journal ArticleDOI
TL;DR: The results indicate that mycelia of AM fungi are influenced by organic matter decomposition both via compounds released during the decomposition process and also by secondary metabolites produced by microorganisms involved in organic Matter decomposition.
Abstract: Soil organic matter is known to influence arbuscular mycorrhizal (AM) fungi, but limited information is available on the chemical components in the organic matter causing these effects. We studied the influence of decomposing organic matter (pure cellulose and alfalfa shoot and root material) on AM fungi after 30, 100, and 300 days of decomposition in nonsterile soil with and without addition of mineral N and P. Decomposing organic matter affected maize root length colonized by the AM fungus Glomus claroideum in a similar manner as other plant growth parameters. Colonized root length was slightly increased by both nitrogen and phosphorus application and plant materials, but not by application of cellulose. In vitro hyphal growth of Glomus intraradices was increased by soil extracts from the treatments with all types of organic materials independently of mineral N and P application. Pyrolysis of soil samples from the different decomposition treatments revealed in total 266 recognizable organic compounds and in vitro hyphal growth of G. intraradices in soil extract positively correlated with 33 of these compounds. The strongest correlation was found with 3,4,5-trimethoxybenzoic acid methyl ester. This compound is a typical product of pyrolysis of phenolic compounds produced by angiosperm woody plants, but in our experiment, it was produced mainly from cellulose by some components of the soil microflora. In conclusion, our results indicate that mycelia of AM fungi are influenced by organic matter decomposition both via compounds released during the decomposition process and also by secondary metabolites produced by microorganisms involved in organic matter decomposition.

90 citations


Journal ArticleDOI
TL;DR: Soil PLFA profiles indicated that the AM fungus exerted a pronounced effect on soil microbial community structure.
Abstract: The effects of an arbuscular mycorrhizal (AM) fungus ( Glomus etunicatum ) on atrazine dissipation, soil phosphatase and dehydrogenase activities and soil microbial community structure were investigated. A compartmented side-arm (‘cross-pot’) system was used for plant cultivation. Maize was cultivated in the main root compartment and atrazine-contaminated soil was added to the side-arms and between them 650 or 37 μm nylon mesh was inserted which allowed mycorrhizal roots or extraradical mycelium to access atrazine in soil in the side-arms. Mycorrhizal roots and extraradical mycelium increased the degradation of atrazine in soil and modified the soil enzyme activities and total soil phospholipid fatty acids (PLFAs). Atrazine declined more and there was greater stimulation of phosphatase and dehydrogenase activities and total PLFAs in soil in the extraradical mycelium compartment than in the mycorrhizal root compartment when the atrazine addition rate to soil was 5.0 mg kg −1 . Mycelium had a more important influence than mycorrhizal roots on atrazine degradation. However, when the atrazine addition rate was 50.0 mg kg −1 , atrazine declined more in the mycorrhizal root compartment than in the extraradical mycelium compartment, perhaps due to inhibition of bacterial activity and higher toxicity to AM mycelium by atrazine at higher concentration. Soil PLFA profiles indicated that the AM fungus exerted a pronounced effect on soil microbial community structure.

Journal ArticleDOI
TL;DR: Ganoderma lucidum species is currently popular and used in the formulation of nutraceuticals and as functional foods, but a broad biochemical characterisation of its mycelium has not yet been reported.

Journal Article
TL;DR: It has been shown that the processing of fruitbody and not the cultivation conditions affects the selected bioactive properties of H. erinaceus.
Abstract: Summary Hericium erinaceus, a temperate mushroom, is currently cultivated in Malaysia. As cultivation and processing conditions may affect the medicinal properties, antimicrobial and antioxidant properties of locally grown H. erinaceus have been investigated. The fruitbodies that were fresh, oven-dried or freeze-dried were extracted with methanol. Their properties were compared to those exhibited by mycelium extract of the same mushroom. Various extracts of H. erinaceus inhibited the growth of pathogenic bacteria but not of the tested fungus. Mycelium extract contained the highest total phenolic content and the highest ferric reducing antioxidant power (FRAP). The fresh fruitbody extract showed the most potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. However, oven-dried fruitbody extract was excellent in reducing the extent of b-carotene bleaching. The total phenolic content and total antioxidant activity in the oven-dried fruitbody extract was high compared to the freeze-dried or fresh fruitbody extract. This may be due to generation and accumulation of Maillard’s reaction products (MRPs), which are known to have antioxidant properties. Thus, the consumption of H. erinaceus fruitbody grown in tropical conditions may have health promoting benefits. Furthermore, the production of H. erinaceus mycelium in submerged cultures may result in standardized antioxidant formulation for either human nutrition or therapy. Hence, it has been shown that the processing of fruitbody and not the cultivation conditions affects the selected bioactive properties of H. erinaceus.

Journal ArticleDOI
Yongcai Li1, Yang Bi1, Yonghong Ge1, X.J. Sun1, Yi Wang1 
TL;DR: In vivo testing showed that Sodium silicate at 100 and 200 mM effectively controlled dry rot of tubers that were challenged by inoculation with a F. sulphureum spore suspension, suggesting that sodium silicate has direct fungitoxic activity against the pathogen.
Abstract: The antifungal activity of sodium silicate on Fusarium sulphureum and its inhibitory effect on dry rot of potato tubers were investigated. Sodium silicate strongly inhibited spore germination and mycelial growth. Morphological changes in sodium silicate-treated hyphae such as mycelium sparsity and asymmetry, hyphal swelling, curling, and cupped shape were observed by scanning electron microscopy. Ultrastructural alterations were also observed using transmission electron microscopy, including thickening of the hyphal cell walls, cell distortion, cavity, or electron-dense material in hyphal cells. Daughter hyphae and new daughter hyphae inside of the collapsed hyphal cells were often detected in the cytoplasm of sodium silicate-treated hyphae, although the septa of treated hyphae remained uniform. In vivo testing showed that sodium silicate at 100 and 200 mM effectively controlled dry rot of tubers that were challenged by inoculation with a F. sulphureum spore suspension. These findings suggest that sodium silicate has direct fungitoxic activity against the pathogen.

Journal ArticleDOI
TL;DR: Results from a field study of the natural attenuation occurring in a slag heap contaminated with high available cadmium showed that spores were related to decomposing vegetal residues and excrements, which means that mesofauna is contributing to their dispersion in the groundmass.

Journal ArticleDOI
TL;DR: The fast mycorrhization process developed here opens the door to a broad range of in vitro studies for which either homogenous highly colonized seedlings or mass-produced in vitro inoculum is necessary.
Abstract: Actively growing extraradical hyphae extending from mycorrhizal plants are an important source of inoculum in soils which has seldom been considered in vitro to inoculate young plantlets. Seedlings of Medicago truncatula were grown in vitro in the extraradical mycelium network extending from mycorrhizal plants. After 3, 6, 9, 12, and 15 days of contact with the mycelium, half of the seedlings were harvested and analyzed for root colonization. The other half was carefully transplanted in vitro on a suitable growth medium and mycelium growth and spore production were evaluated for 4 weeks. Seedlings were readily colonized after 3 days of contact with the mycelium. Starting from 6 days of contact, the newly colonized seedlings were able to reproduce the fungal life cycle, with the production of thousands of spores within 4 weeks. The fast mycorrhization process developed here opens the door to a broad range of in vitro studies for which either homogenous highly colonized seedlings or mass-produced in vitro inoculum is necessary.

Journal ArticleDOI
TL;DR: In continuing the authors' investigation on the bioactive constituents of mycelium of Antrodia camphorata, 4-acetyl-antroquinonol B, 2,3-(methylenedioxy)-6-methylbenzene-1,4-diol and 2,4 -dimethoxy-6- methylbenzenes- 1,3- diol along with antrodin D were isolated and identified on the basis of their spectroscopic analysis.
Abstract: In continuing our investigation on the bioactive constituents of mycelium of Antrodia camphorata, antroquinonol B (1), 4-acetyl-antroquinonol B (2), 2,3-(methylenedioxy)-6-methylbenzene-1,4-diol (3) and 2,4-dimethoxy-6-methylbenzene-1,3-di- " Antrodia camphorata l " Polyporaceae l " mycelium

Journal ArticleDOI
TL;DR: Results show that C. rosea produces beta-1,3-glucanase in situ, which can degrade hyphae of Fusarium and Pythium and contribute to biological control efficacy.
Abstract: Clonostachys rosea f. catenulata (syn. Gliocladium catenulatum) is an effective fungal biological agent against Fusarium root and stem rot and Pythium damping-off diseases on cucumber plants. Both chitinase and beta-1,3-glucanase enzymes were produced when C. rosea was grown on a synthetic medium containing chitin or laminarin as a sole carbon source, respectively. Chitinase production was also induced by Fusarium cell walls, while beta-1,3-glucanase activity was induced by both Fusarium and Pythium cell walls, as well as by growth on homogenized cucumber roots and on low-carbon media. Mycelial growth of Fusarium and Pythium, when exposed to C. rosea culture filtrates that contain glucanase activity, was significantly reduced compared with the controls, and cell walls of both pathogens were degraded. On excised cucumber roots, hyphae of C. rosea formed appressorium-like structures and coiled around hyphae of Pythium. In culture, C. rosea caused localized degradation of Fusarium hyphae. Cucumber root tissues colonized by C. rosea showed higher levels of beta-1,3-glucanase activity at 7 days post-application compared with untreated controls. To determine if this activity was derived from C. rosea, glucanase isoforms were separated on activity gels. Fungal culture filtrates and root extracts contained the same predominant 20 kDa isoform. Reverse-transcription polymerase chain reaction (RT-PCR) using primers designed to amplify a beta-1,3-glucanase gene in C. rosea confirmed glucanase expression on roots. These results show that C. rosea produces beta-1,3-glucanase in situ, which can degrade hyphae of Fusarium and Pythium and contribute to biological control efficacy.

Journal ArticleDOI
TL;DR: The results are the first detailed report of both AMF and DSE associations of these plant species and the use of AMFand DSE during the process of medicinal plant cultivation for pharmaceutical purposes is discussed.
Abstract: Arbuscular mycorrhizal and dark septate endophyte associations of 31 medicinal plant species collected from the Garden of Medicinal Plants of the Faculty of Pharmacy, Jagiellonian University, Collegium Medicum in Krakow were investigated. Arbuscular mycorrhiza (AM) was found in 30 species; 23 were of the Arum-type, 5—Paris and 2 taxa revealed intermediate morphology. Many plants were strongly colonized by arbuscular mycorrhizal fungi (AMF). The mycelium of dark septate endophytes (DSE) was observed in 21 taxa. However, the percentage of root colonization by these fungi was low. Spores of 15 species of AMF (Glomeromycota) were found in the rhizosphere of the investigated plants. Our results are the first detailed report of both AMF and DSE associations of these plant species. The use of AMF and DSE during the process of medicinal plant cultivation for pharmaceutical purposes is discussed.


Journal ArticleDOI
TL;DR: Ozone, an environmentally sound antimicrobial agent, inactivates microorganisms through oxidization and residual ozone spontaneously decomposes to nontoxic products, which may be applied to fruits and vegetables to reduce decay and extend shelf life.
Abstract: Botrytis cinerea and Sclerotinia sclerotiorum are fungal pathogens that cause the decay of many fruits and vegetables. Ozone may be used as an antimicrobial agent to control the decay. The effect of gaseous ozone on spore viability of B. cinerea and mycelial growth of B. cinerea and S. sclerotiorum were investigated. Spore viability of B. cinerea was reduced by over 99.5% (P < 0.01) and height of the aerial mycelium was reduced from 4.7 mm in the control to less than 1 mm after exposure to 450 or 600 ppb ozone for 48 h at 20 degrees C. Sporulation of B. cinerea was also substantially inhibited by ozone treatments. However, ozone had no significant effect on mycelial growth of S. sclerotiorum in vitro. Decay and quality parameters including color, chlorophyll fluorescence (CF), and ozone injury were further assessed for various horticultural commodities (apple, grape, highbush blueberry, and carrot) treated with 450 ppb of ozone for 48 h at 20 degrees C over a period of 12 d. Lesion size and height of the aerial mycelium were significantly reduced by the ozone treatment on carrots inoculated with mycelial agar plugs of B. cinerea or S. sclerotiorum. Lesion size was also reduced on treated apples inoculated with 5 x 10(6) spores/mL of B. cinerea, and decay incidence of treated grapes was reduced. The 450 ppb ozone for 48 h treatment had no significant effect on color of carrots and apples or on CF of apples and grapes. Ozone, an environmentally sound antimicrobial agent, inactivates microorganisms through oxidization and residual ozone spontaneously decomposes to nontoxic products. It may be applied to fruits and vegetables to reduce decay and extend shelf life.

Journal ArticleDOI
Yong-cai Li1, Xiao-juan Sun1, Bi Yang1, Yong-hong Ge1, Yi Wang1 
TL;DR: Application of chitosan at higher concentration caused serious damage to fungal hyphae, including cellular membrane disorganisation, cell wall disruption, and breaking of inner cytoplast.

Journal ArticleDOI
TL;DR: The Muscodor yucatanensis sp. nov. as discussed by the authors is a member of the Xylariales with high similarity to Muscodors albus and the related species muscodor vitigenus, but with distinct differences.
Abstract: During a study on the fungal endophytic associations with some trees of the secondary forest of El Eden Ecological Reserve located in the northeastern Yucatan Peninsula of Mexico, a new fungal species was isolated as an endophyte of a tree named chakah, chachah, or hukup (Bursera simaruba) by indigenous Mayas. This fungus is characterized by producing a strong musty odor and absence of reproductive structures. Cultures of this fungus on PDA form a whitish, flocculose colony with an uncolored reverse and a mycelium that grows slowly. Scanning electron microscopy photographs showed in aerial and submerged mycelium the early formation of unique intercalary swollen, thin-walled, rugulose hyphae. Based on morphological and DNA sequence analyses, the Mexican isolate is a member of the Xylariales with high similarity to Muscodor albus and the related species Muscodor vitigenus, but with distinct differences that is here described and illustrated as Muscodor yucatanensis sp. nov.

Journal ArticleDOI
TL;DR: The contents of major bioactive components, cordycepin and adenosine in fruiting bodies and mycelia from the nature C. sinensis and artificial cultural C. militaris were investigated using improved HPLC method and showed the concentrations were higher than that in natural C. Sinensis.
Abstract: Cordyceps sinensisis, a kind of precious natural crude drugs and edible mushrooms, were used as tonic food in East Asia area and enjoyed an extensive praise for its medicinal functions. Cordyceps militaris, as a substitute for C. sinensis, is a widely distributed species, which can be cultivated in various medium. In this study, the contents of major bioactive components, cordycepin and adenosine in fruiting bodies and mycelia from the nature C. sinensis and artificial cultural C. militaris were investigated using improved HPLC method. The results showed the mean contents of cordycepin and adenosine in the fruiting bodies of C. militaris were 2.654 ± 0.02 and 2.45 ± 0.03 mg/g, those in C. sinensis were 0.9801 ± 0.01 and 1.643 ± 0.03 mg/g, while those in the mycelium of C. militaris were 0.9040 ± 0.02 and 1.592 ± 0.03 mg/g, respectively. The concentration of cordycepin and adenosine in the fruiting bodies of C. militaris were higher than that in natural C. sinensis, while the fermented mycelium of C. militaris were similar with natural C. sinensis.

Journal ArticleDOI
TL;DR: Concentrations of P in extraradical mycelium were much lower than usually found in plants and fungi, while P concentrations in associated mycorrhizal host plant tissues were in an optimum range, which suggests efficient transfer of P from the extaradicalMycelium to the host plant.
Abstract: Sweet potato plants were grown with or without Glomus intraradices in split-root pots with adjacent root compartments containing a soil with a low availability of phosphate. One fungal tube, from which root growth was excluded, was inserted into each root compartment. During 4 weeks before harvest, the soil moisture level in either both or only one of the two root-compartments of each pot was decreased. Controls remained well watered. Low soil moisture generally had a negative effect on the amount of extraradical mycelium of G. intraradices extracted from the fungal tubes. Sporulation in the fungal tubes was much higher compared with the soil in the root compartment, but remained unaffected by the soil moisture regime. Concentrations of P in extraradical mycelium were much lower than usually found in plants and fungi, while P concentrations in associated mycorrhizal host plant tissues were in an optimum range. This suggests efficient transfer of P from the extraradical mycelium to the host plant. Despite the negative effect of a low soil moisture regime on extraradical G. intraradices development, the symbiosis indeed contributed significantly to P uptake of plants exposed to partial rootzone drying. The possibility that extraradical arbuscular mycorrhizal fungal development was limited by P availability under dry soil conditions is discussed.

Journal ArticleDOI
TL;DR: Activity of an antagonistic bacterium indicated that the type of suppressiveness against Rhizoctonia disease by the vermicompost is specific.
Abstract: Disease suppressiveness of vermicompost produced from agricultural wastes consisting of cattle manure, tree bark (Salix spp.), potato culls, and apples was assayed on damping-off of two days-old cucumber (Cucumis sativus cv. Cevher) seedlings infected by Rhizoctonia solani Kuhn (AG-4). Suppression effect was assessed at the rates of 0, 10, 20 and 30% (v/v) vermicompost, either blended with Trichoderma harzianum Rifai (KRL-AG2), amended with potting mixtures consisting of sand and garden soil (1:1, v/v). Effect of water extracts of vermicompost on growth of R. solani mycelium in Petri dishes was also analyzed. Disease suppression effect increased in proportion to the pot amendment rate of vermicompost. Vermicomposts not blended with T. h arz ian u m effectively controlled damping-off of cucumber by R. solani (AG-4) at the rate of 20% and 30%. Vermicompost not blended with T. harzianum improved plant growth as well as that blended with T. harzianum. Analysis of the effect of water extracts of vermicompost on growth of R. solani mycelium in Petri dishes revealed antagonistic activity of a putative bacterium. Heat sterilization eliminated the suppressive and antagonistic effect by vermicompost and its water extracts, respectively. Activity of an antagonistic bacterium, which expressed a strong inhibition of growth of the pathogen mycelium, indicated that the type of suppressiveness against Rhizoctonia disease by the vermicompost is specific.

Journal ArticleDOI
TL;DR: Tea compost reduced disease incidence by 19% when used as a preventive treatment and eradicated the pathogen on the leaves when applied as a curative treatment and was rich in inorganic salts, organic carbon and phenols, which can affect pathogen growth and phyllosphere microorganisms.
Abstract: The use of compost tea extracts to control leaf diseases is an alternative that enables the use of chemicals in agriculture to be reduced. However, little is known about the mechanisms responsible. We examined an aerated compost tea prepared from composted market and garden wastes and tested its effect on naturally occurring powdery mildew disease produced by the foliar pathogen Erysiphe polygoni in tomato plants (Lycopersicon esculentum cv. Roma) grown in perlite in an unheated greenhouse. Untreated plants showed whitish patches of powdery mildew, while in the treated plants the mycelium could hardly be seen and leaves only showed localized yellow spots corresponding to former sites of infection. Tea compost reduced disease incidence by 19% when used as a preventive treatment and eradicated the pathogen on the leaves when applied as a curative treatment. Treatment was not associated with increased peroxidase or chitinase activity in the leaves and induction of local resistance is unlikely to have been responsible. Instead, the effects of the compost could be due to the presence of bacteria and fungi, which may act as antagonists to the pathogen. The compost was rich in inorganic salts, organic carbon and phenols, which can affect pathogen growth and phyllosphere microorganisms.

Journal ArticleDOI
TL;DR: Findings provide evidence that cryopreservation at -80 degrees C and lyophilisation are suitable alternatives to liquid nitrogen cryop Reservation for preservation of some WRF strains.

Journal ArticleDOI
TL;DR: The optimal initial pH for the spore production of B. bassiana using Potato Dextrose Broth was 5.2, which represents a yield gain of approximately 2.89 times that of pre-optimization.
Abstract: In recent years, there has been a resurgence of interest in the use of fungi for the control of insect pests. This revival of interest has led to the large-scale production of several promising fungi candidates, and also to the marketing of the first commercial mycoinsecticides. Beauveria bassiana (Balsamo) Vuillemin is a fungus with a broad natural distribution; its potential to control more than 70 insect pests has been responsible for a substantial increase in interest in the large-scale production of the fungus for applications in the field (Thomas et al., 1987). Moreover, this fungus also appears to be innocuous to most non-target organisms. Efforts to improve potential control agents often center around an appropriate mass-production method for the suitably large-scale production of the infective propagules. The mass production of insect-pathogenic fungi is a necessary prerequisite for any large-scale field application employing these fungi. The most frequently utilized technique for the cultivation of fungal spores is either a surface culture with a solid substrate, such as moistened wheat bran, millet or rice, or a submerged culture with a liquid medium (Feng et al., 2000). Submerged cultivation may have the advantage that fungi can be rapidly generated using conventional deep-tank fermentors, and the scale-up of this process is relatively easy. Submerged cultivation also has a number of highly desirable attributes: they are cheaper, particularly on a very large scale; environmental factors (pH, pO2, pCO2, nutrient levels) can be more readily controlled, and growth can be easily monitored (Bartlett and Jaronski, 1988). Harvesting from submerged fermentations is also made substantially easier, as the spores can be readily collected and concentrated via centrifugation, filtration, etc., and then dried. The entomopathogenic hyphomycete fungi are generally easy to grow on a large scale, and can be cultivated on cheap media in submerged cultures. Depending on the strain, medium, and culture parameters, the fungal biomass is increased via vegetative growth forming either hyphal filaments, often with copious branching, or various forms of flocs and pellets of mycelia (Brown et al., 1988). The majority of fungal isolates are also capable of forming single cells via schizolytic separation at the septa or mechanical fragmentation of the hyphae, and can also be generated from the hyphae by yeast-like budding (Rombach, 1989; Jackson et al., 1990). Hyphal cells, which are also referred to as hyphal bodies or blastospores, are usually the only type of propagules produced in liquid fermentation schemes (Thomas et al., 1987; Jenkins et al., 1993). Previously, we isolated the entomopathogenic B. bassiana KK5, which exhibits particularly high infectivity to aphids. Despite its high levels of infectivity, the large-scale application of this fungus for the control of aphids in the field is possible only in cases in which the fungus can be grown and can produce high spore titers economically, on readily available substrates. The primary objective of the present study was to evaluate the influences of different carbon and nitrogen sources and main culture parameters on blastospore yields in submerged fermentation cultures of the B. bassiana KK5 isolate. First, the effects of differing pH values, temperatures, medium compositions, and C/N ratios were optimized in shake flasks. Sporulation was then optimized using different substrates. Finally, blastospore production was carried out using these optimized parameters.

Journal ArticleDOI
TL;DR: Results indicate that morphology changes affected the lipaseProduction significantly for R. chinensis and the aggregated mycelia were suggested to achieve high lipase production.
Abstract: In order to control suitable mycelium morphology to obtain high lipase productivity by Rhizopus chinensis in submerged fermentation, the effects of fungal morphology on the lipase production by this strain both in shake flask and fermentor were investigated. Different inoculum level and shear stress were used to develop distinctive morphologies. Analyses and investigations both on micromorphology and macromorphology were performed. Study of micromorphology reveals that micromorphologies for dispersed mycelia and aggregated mycelia are different in cell shape, biosynthetic activity. Macromorphology and broth rheology study in fermentor indicate that pellet formation results in low broth viscosity. Under this condition, the oil can disperse sufficiently in broth which is very important for lipase production. These results indicate that morphology changes affected the lipase production significantly for R. chinensis and the aggregated mycelia were suggested to achieve high lipase production.