Showing papers on "Mycelium published in 1984"

The ecology and physiology of the fungal mycelium.

Abstract: Contributors Preface Nomenclature 1. The fungal mycelium - and historical perspective P. H. Gregory 2. Regulation of hyphal branching and hyphal orientation A. P. J. Trinci 3. Colony ontogeny in basidiomycetes G. M. Butler 4. Hyphal interactions in Schizophyllum commune: the di-mon mating T. T. Nguyen and D. J. Niderpruem 5. Hyphal fusion in Coriolus versicolor R. C. Aylmore and N. K. Todd 6. The mycelial habit and secondary metabolite production M. O. Moss 7. Water flow through mycelia D. H. Jennings 8. Morphogenesis of the Serpula lacrimans colony in relation to its functions in nature S. C. Watkinson 9. Distribution, development and functioning of mycelial cord systems of decomposer basidiomycetes of the deciduous woodland floor W. Thompson 10. The structure and function of the vegetative mycelium of mycorrhizal roots D. J. Read 11. Autecology and the mycelium of a woodland litter decomposer J. C. Frankland 12. The micro-environment of basidiomycete mycelia in temperate deciduous woodlands L. Boddy 13. Interrelationships between vegetative development and basidiocarp initiation M. Raudaskoski and M. Salonen 14. Physiology and ecology of rhythmic growth and sporulation in fungi G. Lysek 15. Senescence in Podospora anerina and its implication for genetic engineering K. Esser, U. Kuck, U. Stahl and P. Tudzynski 16. The mycelial biology of Endothia parasitics. I. nuclear and cytoplasmic genes that determine morphology and virulence S. L. Anagnostakis 17. Variation and heterokaryosis in Rhizoctonia solani N. A. Anderson 18. Interspecific mycelial interactions - an overview A. D. M. Rayner and J. F. Webber 19. Mycelial development and lectin-carbohydrate interactions in nematode-trapping fungi B. Nordbring-Hertz 20. Mycelial interactions and mitochondrial inheritance in Aspergillus J. H. Croft and R. B. G. Dales 21. Inter-mycelial recognition systems in Ceratocystis ulmi: their pysiological properties and ecological importance C. M. Brasier 22. The mycelial biology of Endothia parasitica. II. vegetative incompatibility S. L. Anagnostakis 23. The biological consequences of individualistic mycelium A. D. M. Rayner, D. Coates, A. M. Ainsworth, T. J. H. Adams, E. N. D. Williams and N. K. Todd Index of generic and specific names Subject index.

The effect of phosphorus on the formation of hyphae in soil by thevesicular‐arbuscular mycorrhizal fungus, glomus fasciculatum

Abstract: Summary Hyphae formed in soil by the vesicular-arbuscular (VA) mycorrhizal fungus, Glomusfasciculatum (Thaxter sensu Gerd.) Gerd. and Trappe were extracted using the membrane filter techniqe and their length was estimated by the grid intersection method. The effect of phosphorus on the formation of this external mycelium was assessed after sampling procedures had been investigated. Phosphorus supply was varied from amounts severely deficient to those adequate for the growth of subterranean clover. After 6 weeks, the alleviation of severe phosphorus deficiency increased both the length of infected root and the length of external hyphae per centimetre of infected root. Further additions of phosphorus decreased both of these measurements. However, the level of added phosphorus at which the most external hyphae was formed per centimetre of infected root was higher than the level of phosphorus which gave the greatest length of infected root. The increase in phosphorus supply which gave the greatest increase in the length of external hyphae per centimetre of infected root also decreased the formation of vesicles within infected roots. At phosphate levels adequate for growth of mycorrhizal plants, there was little development of either external hyphae in soil or vesicles within the mycorrhizal roots.

Direct transfer of carbon between plants connected by vesicular–arbuscular mycorrhizal mycelium

Abstract: Mycorrhizal infection of plants in many natural vegetation systems arises when uninfected roots make contact with mycelia spreading from infected roots1,2. The result of the infection is that connections are present between the roots of individual plants. It has been shown by autoradiography that these interconnections provide a direct pathway for the transfer of carbon between ecto-mycorrhizal plants2,3. Inter-plant transfer of carbon4 and phosphorus5–7 has been reported in plants with vesicular–arbuscular (VA) mycorrhizas, but in the absence of comparable evidence it remains a possibility that in these cases the pathway is indirect, uptake by the fungus of the ‘receiver’ plant occurring only after leakage of the nutrients from roots of the ‘donor’. We now show using autoradiography that transfer of carbon between plants connected by VA mycorrhizal mycelium occurs primarily by the direct hyphal pathway. It is further shown that the magnitude of the transfer is strongly influenced by shading of ‘receiver’ plants indicating that movement is governed by source–sink relationships.

Morphological and Physiological Differentiation in Streptomyces

Abstract: A GENERAL INTRODUCTION TO STREPTOMYCES The names of many organisms reflect their special biological properties. The name Streptomyces describes a unique morphology, albeit inaccurately: The word means “chain fungus,” although streptomycetes are undoubtedly bona fide gram-positive bacteria. The branching hyphae characteristic of Streptomyces vegetative growth form a complex substrate mycelium (Fig. 1a, b) that penetrates and solubilizes organic debris, typically in soil, by the action of extracellular hydrolytic enzymes. The inherent immobility of the mycelium is counterproductive to distribution, a problem solved (as in eukaryotic molds) by spore formation (Fig. 1c, d). Long chains of spores (often containing >50 spores) usually form from specialized aerial hyphae, which themselves apparently develop mainly by cannibalizing the vegetative mycelium. At this vulnerable stage in development, when the lysing mycelium might easily be consumed by invading motile microorganisms, it is not surprising to find that chemical defense mechanisms are employed. Indeed, nearly all of the thousands of known antibiotics are made by streptomycetes and molds, usually at a time coinciding with that of aerial mycelium formation. The idea has developed that genes for antibiotic production may therefore be subject to at least some of the regulatory mechanisms involved in setting off aerial mycelium formation and that studies of the one will provide information about the other. In this paper descriptions of growth and morphological differentiation (first two sections) are followed by a summary of Streptomyces genetic phenomena and tools and their use in analyzing sporulation. The section, Physiological Differentiation: Production of Secondary Metabolites deals...

Isolation and characterization of concanamycins a, b and c

Abstract: Concanamycins A, B and C were isolated from the mycelium of Streptomyces diastatochromogenes S-45 as effective inhibitors of the proliferation of mouse splenic lymphocytes stimulated by concanavalin A. They represent a new class of 18-membered macrolide antibiotics, and are biologically active in vitro against several fungi and yeasts, but not against bacteria. Concanamycin A, the main component, has been identified with antifungal antibiotics, folimycin and A-661-I.

Cadmium Uptake by Aureobasidium pullulans

Abstract: SUMMARY: Yeast-like cells, mycelium and melanin-pigmented chlamydospores of Aureobasidium pullulans accumulated cadmium from cadmium-containing medium. With chlamydospores, uptake was rapid and independent of temperature and the presence of glucose, and corresponded to binding of cadmium to cell surfaces. With yeast-like cells and mycelium, the initial rapid surface adsorption of cadmium was up to six times lower than that of chlamydospores, and was followed by metabolism-dependent transport of cadmium into the cytoplasm. The second phase of uptake was slower and followed Michaelis-Menten kinetics. Concomitant with the intracellular accumulation of cadmium was an efflux of potassium, two K+ ions being released for each Cd2+ ion accumulated. Potassium loss was low in comparison to the cell potassium levels and there was no loss of viability by any cell type at cadmium concentrations up to 0.5 mM. In yeast-like cells and mycelium, Ca2+ ions were found to inhibit cadmium uptake competitively. Work with the ionophore valinomycin confirmed that potassium efflux and cadmium influx occurred at different sites on the plasma membrane of yeast-like cells. Intracellular cadmium could be actively excreted from cells.

Morphological development of Aspergillus niger immobilized in Ca-alginate and K-carrageenan

Abstract: The morphological development of citric acid producing Aspergillus niger immobilized in Ca-alginate and K-carrageenan was studied. The fungus normally developed a dense mycelium layer below and on the gel bead surfaces so that substrate and oxygen in this area had direct contact with mycelia. By this way mycelia are not only immobilized by entrapment but also in a “pellet-like” matter. Limitation of the nitrogen source induces a more interior mycelium growth, and outgrowing of free cells was minimized. In sucrose media no effect on the particle stability was observed whereas the application of potassium acetate as substrate caused the complete dissolving of the matrices.

The growth characteristics of Saccharomycopsis lipolytica: morphology and induction of mycelium formation

Abstract: When Saccharomycopsis lipolytica was grown on minimal medium supplemented with glucose or n-hexadecane, all the cells of the culture remained in the yeast form. In complex medium, a mixed morphology of yeast and mycelial forms appeared. If the cells were grown on minimal medium supplemented with N-acetylglucosamine as the carbon source, a reproducible system for the production of mycelium was obtained. Neither temperature, pH, nor several other carbon sources were able to induce a reproducible yeast–mycelial transition. Mycelium formation is maximal after 12–15 h of incubation (in the presence of N-acetylglucosamine) and decreases with longer incubating times when N-acetylglucosamine is exhausted. During mycelium formation a considerable increase took place in dry weight; the cell numbers, however, remained almost constant between 12–15 h. Electron microscopy shows mycelium with a smooth surface, a great amount of mitochondria and a low degree of branching.

Phosphate uptake by goodyera repens in relation to mycorrhizal infection

Abstract: Summary The rate of P uptake per unit length of root of adult plants of the orchid Goodyera repens Br., infected with the mycorrhizal endophyte Rhizoctonia goodyerae-repentis Constantin and Dufour, was up to 100 times greater than that of non-mycorrhizal plants. When the active extramatrical mycelium was reduced by treatment with thiabendazole fungicide, the relative growth rate of mycorrhizal plants was reduced in low P conditions but not in P rich conditions. Rates of P uptake into fungicide-treated plants were Jess than those of mycorrhizal plants at both P levels. Translocation of 32P from a point source to the plant via the extramatrical mycelium was demonstrated and could be inhibited by the application of thiabendazole. In a model system incorporating a perlite/Vermiculite substrate, translocation of 32P via the endophyte took place over distances up to 9 cm. The mycorrhiza of adult G. repens appears similar to other mycorrhizas in its ability to enhance growth and P uptake.

Observations on the introduction of Verticillium chlamydosporium and other parasitic fungi into soil for control of the cereal cyst-nematode Heterodera avenae.

Abstract: SUMMARY Isolates of Verticillium chlamydosporium and a sterile fungus added to soil on ground oat grain reduced the numbers of Heterodera avenae on wheat by between 26 and 80%. Nematode populations in uninoculated soil increased from 15 eggs/g soil before planting to 218 eggs/g after harvest. V. chlamydosporium was isolated from oat grain that had been air-dried and milled before introduction into soil. Applications of the fungi on attapulgite clay or as suspensions of mycelium and spores in water had no effect on nematode multiplication. The effect of the fungi on numbers of H. avenae eggs was similar in autoclaved and non-sterilised soil. V. chlamydosporium added on attapulgite clay to a calcareous sand and a calcareous silty loam could be re-isolated after at least 6 months. Some isolates colonised the roots of wheat without causing lesions or affecting the dry weights of shoots or roots. These results indicate that V. chlamydosporium may be useful for the biological control of cyst nematode pests.

Chemical constituents of Armillaria mellea mycelium. I. Isolation and characterization of armillarin and armillaridin.

Abstract: Two new sesquiterpenoid aromatic esters, armillarin and armillaridin, have been isolated from the artificially cultured mycelium of ARMILLARIA MELLEA (Vahl. ex Fr.) Quel. (Tricholometaceae). On the basis of spectral (UV, IR, 1 H-NMR, 13 C-NMR and MS) analysis and chemical degradation as well as X-ray crystallography, their structures were identified as ( 1) and ( 2), respectively.

Phytoalexin accumulation during infection of bean and soybean by ascospores and mycelium of Sclerotinia sclerotiorum

Abstract: Infection by ascospores of Sclerotinia selerotiorum caused hypersensitivity in epidermal cells in leaves and etiolated hypocotyls of bean and soybean. In bean, phaseollin and phaseollidin accumulated in leaves but kievitone alone in hypocotyls. In soybean, no phytoalexins were detected in leaves but glyceollin accumulated in hypocotyls. Mycelial infection caused water-soaked spreading lesions in leaves and etiolated hypocotyls of both hosts. In bean, no phytoalexins were detected in leaves but kievitone alone accumulated in hypocotyls. In soybean, glyceollin accumulated in leaves but was not sought in hypocotyls. Transfer of bean hypocotyls infected with mycelium from 18 to 28°C caused lesion limitation and marked accumulation of phaseollin and kievitone. Phaseollin, kievitone and glyceollin inhibited ascospore germination and growth of hyphae from preformed germ-tubes and established mycelia, phaseollin being most active and glyceollin least active. Hyphal growth from mycelia was least affected by the phytoalexins.

The effect of mycorrhizal infection of goodyera repens and its control by fungicide

Abstract: Summary Studies of the orchid Goodyera repens Br. growing on agar media in association with its natural endophyte Rkizoctonia goodyerae-repentis Constantin and Dufour showed that mycorrhizal plants of different developmental stages had significantly higher growth rates and level of P and N than did uninfected ones. Treatment of mycorrhizal plants with the fungicide thiabendazole stopped growth of external mycelium and caused a significant decrease in growth rate, P and N content, percentage infection and net assimilation rate. These results suggest that the mycorrhizal fungus enhances nutrient uptake and allows greater growth rates, a situation similar to that found in non-orchid mycorrhizas.

Synthesis and degradation of aflatoxins by Aspergillus parasiticus. I. Synthesis of aflatoxin B1 by young mycelium and its subsequent degradation in aging mycelium.

Abstract: Aflatoxin production and degradation were examined in three isolates of A. parasiticus. Maximum yields were present after incubation for 14 days and these declined gradually as the culture aged. Young mycelia (4 days old) synthesized the greatest amounts of aflatoxin, but aging mycelia (14 days old) were mainly responsible for degradation. Addition of cycloheximide to young cultures and removal of mycelia from aging cultures both prevented further aflatoxin degradation. Intramycelial substances released from fragmented or homogenized mycelium were capable of degrading aflatoxins, and their concentration increased as the mycelium aged. When 14C-labelled aflatoxin was added to a 2-day-old culture and further incubated, 75% of the radioactivity at 12 days was intramycelial, but at 20 days, most radioactivity was in the filtrate.

Interactions between Sclerotium rolfsii and Trichoderma spp: Relationship between antagonism and disease control

Abstract: Ten isolates of Trichoderma spp were examined for their ability to antagonize growth and to parasitize mycelium of Sclerotium rolfsii (Sr-1) on agar media, to inhibit germination of sclerotia of S. rolfsii on natural soil plates and to sporulate on the sclerotia, and to protect bean seedlings against the pathogen in the greenhouse. A high negative correlation ( r = −0.844) was observed between plant stand in the greenhouse and sclerotial germination on soil plates but not with antagonism on agar plates. Three isolates of T. harzianum (Th-7, Th-20, WT-6) and one of T. hamatum (TRI-4) were especially effective in reducing sclerotial germination and controlling disease in the greenhouse. Three isolates of Trichoderma spp (WT-6, TMP, and TRI-4), effective in reducing sclerotial germination of isolate Sr-1, also prevented sclerotial germination in four out of five additional S. rolfsii isolates studied.

Deterioration of mycorrhizal short roots and occurrence of Mycelium radicis atrovirens on declining Norway spruce in Bavaria

Abstract: From four locations in Bavaria, the only known pathogenic fungi identified from fine roots (< 2mm dia) of declining Norway spruce (Picea abics) were Cylindrocarpon destructans and Mycelium radicis atrovirens, the latter being much more common (25 vs. 95 isolations from 219 root segments). Norway spruce from six additional locations were sampled for mycorrhizae and fine roots. There were always more active mycorrhizal root tips (1.28 to 3.44 fold) on spruce which were less symptomatic of decline [P(T) = 0.0156]. However, the occurrence of inactive mycorrhizae and M. r. atrovirens were similar on all spruce that were sampled. In tins study, no evidence was found that a root pathogen is causing the deterioration in the fine root system of declining Norway spruce.

A species-specific method of analysing populations of basidiospores

Abstract: A method using homokaryotic mycelia to investigate the dissemination and deposition of viable spores of heterothallic basidiomycetes, is described and its application discussed.

Spore germination in the higher Basidiomycetes

Abstract: This survey of the spore germination requirements in the Hymenomycetes and the Gasteromycetes shows that saprophytes as xylophiles, which decompose wood and forest litter, and coprophiles, which live on dung, usually germinate easily even on simple nutrient media. Species forming ectomycorrhiza with trees or living as parasites require as a rule more particular conditions for germination. In the mycorrhiza-formers, chiefly agarics and boleti, germination can often be induced by exudates from tree roots or certain yeasts, in species ofLeccinum by exudate from self mycelium. The heartrot fungi, chiefly those species of Aphyllophorales which are parasites on trees, germinate preferably when exposed to an increased CO2 content in the air or to exudates of certain micro-organisms. In many praticolous fungi, which are supposed to parasitize roots of grasses and herbs, germination is stimulated by various yeasts. The possibility of interpreting these particular germination conditions as adaptations to a parasitic or symbiotic life is discussed.

In vitro digestion of wheat straw by different rumen anaerobic fungi

Abstract: Two types of anaerobic fungi were isolated from the rumen of a sheep fed wheat straw. The fungus producing a mycelium in culture digested significantly more organic matter, neutral detergent fiber, acid detergent fiber and cellulose from straw than the type producing a sporangium from "spherical bodies." Key words: Rumen, fungi, straw, fiber digestion

Protoplast release from fungi capable of steroid transformation

Abstract: Protoplasts were obtained from Hyphoderma roseum (Fries) and Cunninghamella elegans (Lendner), fungi capable of steroid 11-hydroxylation. The lytic enzyme preparation was derived from Trichoderma viride CBS 354-33. Homogeneous protoplast suspension, free of mycelial debris and cell wall fragments, transformed cortexolone and 6α-fluorocortexolone-16,17-acetonide to the same products as the intact mycelium of the microorganisms. Liberation of protoplasts and their stabilizaiton during steroid transformation was the most effective in 0.8 M MgSO4; still, this compound impaired steroid hydroxylation. Consequently, the concentration of the transformation product formed was nearly the same as in sucrose, mannitol, and sorbitol, compounds which caused no inhibition but which were less effective stabilizers.

Factors affecting spore formation in a Candida albicans strain.

Abstract: Growth and spore formation of Candida albicans Y-45 was enhanced by low oxygen tension. Mycelium and chlamydospores were abundantly found on rice infusion-Tween 80 agar within 48 to 96 h, and abundant chlamdospore production occurred most rapidly under reduced oxygen tension and incubation at 30 degrees C. Zn, Mg, Mn, anf Fe were tested for their ability to promote filamentation in C. albicans Y-45. Filamentation under conditions of low Mg and high Mn suggested that morphogenesis is possibly correlated with the presence of salts of these heavy metals.

Aggregation of surface mine soil by interaction between VAM fungi and lignin degradation products of lespedeza.

Abstract: The external mycelium of a vesicular-arbuscular mycorrhizal (VAM) fungus was effective in aggregating a sandy loam minesoil. The polysaccharide nature of the soil binding agent on hyphal surfaces and on the surfaces of sand particles in contact with the hyphae within the aggregate was demonstrated with the periodic acid-Schiff reagent staining reaction. A possible stabilizing mechanism for macroaggregates was proposed that involves a coupling reaction between glucosamines in the hyphal walls of the fungus with phenolic compounds released during lignin degradation of sericea lespedeza root tissue.

Detection of mycelium and oospores of Phytophthora megasperma forma specialis glycinea by vital stains in soil.

Abstract: Eight different vital stains were tested on mycelium and oospores of Phytophthora megasperma f. sp. glycinea race 1. Acridine orange, fluorescein diacetate, neutral red, and tetrazolium bromide differentiated living from dead mycelium in vitro and on membrane filters in soil. Fluorescein diacetate and tetrazolium bromide also differentiated living from dead mycelium added directly to soil. Mycelium buried in soil or on the surface of soil with a moisture content adjusted to -0.1 bars matric potential at 24 C for 8 da failed to stain. Fluorescein diacetate and tetrazolium bromide selectively stained living oospores in vitro, on membrane filters incubated in soil, or directly added to soil. Oospore viability was measured best by tetrazolium bromide. Oospores on membrane filters were buried in soil adjusted to 0 bars at 24 C. After 12 wk, tetrazolium bromide stained at least 90% of the oospores. Microscopic observation and detection of fungal propagules in soil may be enhanced by the use of stains (3, 6, 8-12). Very few studies of fungi in soil have employed stains that determine viability of fungi in soil. Previously, most studies have used fluorescent brightener stains to follow growth, morphological development and survival (11). However, fluorescent brightener stains do not measure adequately the viability of dormant fungal structures. Two vital stains, fluorescein diacetate and tetrazolium bromide, may be more appropriate for determining the viability of dormant fungal structures such as oospores. Fluorescein diacetate has been tested on Phytophthora mycelium in vitro and in soil by Soderstrom (8) but oospores were not included in the study. Ribeiro (6) has stained Phytophthora oospores with tetrazolium bromide only in an in vitro system. Consequently, this study examined several stains for the ability to enhance observation of mycelium and oospores of Phytophthora megasperma f. sp. glycinea in soil. Also, the staining results were examined to ascertain if activated oospores can be distinguished from dormant oospores on membrane filters incubated in soil.

Fungal abundance on Lolium perenne roots: Influence of nitrogen and phosphorus

Abstract: In four experiments, Lolium perenne was grown in pots of soil known to be deficient in nitrogen and phosphorus. Weekly additions of soluble nutrients provided treatments of markedly differing nitrogen and phosphorus supply, which significantly affected plant growth. Fungal abundance on the root surface, expressed as length of mycelium per unit root surface area, was determined by direct observation. It was increased, usually several-fold, when either nitrogen or phosphorus was omitted from the nutrient supply, and showed a close negative relation to plant weight. When expressed as mycelium weight/plant weight the increase was tenfold or more. In a sand culture experiment, in which the plants were inoculated with a single saprophytic fungus species, the results showed some similarities to the soil experiments, but were inconclusive. Possible mechanisms for the changes in fungal abundance are discussed.

The Nitrate Reductase System

Abstract: It has been proposed by Klemm and Ninnemann [29] that nitrate reductase (NR) may act as a photoreceptor in blue light-stimulated conidiation of Neurospora crassa (carotenoid-less mutant al-2 bd). Nitrate reduction and conidiation appear to be correlated in some specific ways: Hochberg and Sargent [19] and Weiss and Turian [61] reported that conidiation of Neurospora is maximally supported by nitrate as sole nitrogen source in the medium, whereas the mycelium grows optimally with ammonium nitrate or diammonium citrate. Weiss and Turian [61] also described suppression of conidiation on diammonium citrate (+ 2% sucrose). The same amino acids (e.g., try, ala, his) appear to be favorable for conidiation [47] and induction of NR [51]. We found [26] that hyphae grown on nitrate formed conidia under starvation conditions (nitrogen and carbon source depleted, possibly partial anaerobiosis) whereas conidia occurred much later if at all when the mycelium was starved after growth on medium containing NH4NO3 (Fig. 1A and B). Also light-induced absorbance changes at 423 and 557 nm — regarded as an assay system for a primary process in the vicinity of the photoreceptor — could be seen in vivo in Neurospora mycelium only at a time when light stimulated conidiation [28]. We have done preliminary experiments which show that the light requirement for promotion of conidiation decreased in somatic fusion products nit 1 + 3 made from protoplasts of nitrate reductase-deficient nit-1 and nit-3 mutants of Neurospora as compared with the parental strains [37].

Uptake of [14c]glucose by asymbiotic and mycorrhizal orchid protocorms

Abstract: Summary In cultures of Goodyera repens Br. infected with its natural mycorrhizal endophyte, Ceratobasidium Cornigerum (Bourdot) Rogers, 14C supplied as glucose reached a peak in the external mycelium within 48 h but accumulated in protocorms over several days. Uptake directly from the substrate into non-infected protocorms was much slower with less incorporation of 14C into insoluble material than occurred in infected protocorms. There was a similar pattern of uptake from two Ceratobasidium spp. into Dactylorhiza purpurella (T. & T. A. Steph) Soo but the amount of glucose accumulated was less using a natural endophyte than with an isolate originally obtained from rice plants. Using an un-named Cymbidium hybrid in symbiosis with Ceratobasidium sp. from D. purpurella, there were low rates of uptake into both non-infected and infected protocorms. 14C from glucose appeared in mannitol and trehalose in mycelium but mainly in glucose, fructose and sucrose in the orchid, with traces of trehalose in infected tissue. In freshly-infected protocorms, only trehalose became labelled in the pre-digestive phase of infection and there was no evidence of transfer of 14C from fungus to host before digestion of hyphae occurred.