The Hydrophobin HCf-1 of Cladosporium fulvum Is Required for Efficient Water-Mediated Dispersal of Conidia

Six hydrophobin genes (HCf-1 to -6) have thus far been identified in the tomato pathogen Cladosporium fulvum. HCf-1 to -4 are Class I hydrophobins and HCf-5 and -6 are Class II hydrophobins. In this paper we describe the isolation of deletion mutants that lack HCf-1, HCf-2, or both these genes. Global down-regulation of the expression of Class I hydrophobins is achieved by homology-dependent gene silencing. Analysis of the mutant strains shows that HCf-1 confers hydrophilic character to the conidia and this facilitates the dissemination of conidia on the surface of water droplets. Other Class I hydrophobins, such as HCf-3 or HCf-4, may be involved in the development and germination of conidia.     

Infection of Sentinel Cotton Aphids (Homoptera: Aphididae) by Aerial Conidia ofNeozygites fresenii(Entomophthorales: Neozygitaceae)

Uninfected adultAphis gossypii(Homoptera: Aphididae) apterae (sentinel aphids) on cotton leaves were exposed for 8 h to the air over a commercial cotton field in Louisiana during the night of 1–2 July 1995. At 0015 h there were 90,437 primary conidia/m³air of the fungusNeozygites fresenii(Entomophthorales: Neozygitaceae) at the midfield position as determined from Rotorod samples. Forty-eight percent (n = 106) of the sentinel aphids exposed for 8 h at midfield were infected by aerial conidia ofN. fresenii.Exposure of sentinel aphids outside the cotton field, at 10 and 100 m downwind and 10 m upwind, resulted in 34.8% (n = 131), 24.0% (n = 129), and 17.4% (n = 146) infected aphids, respectively. These data demonstrate that wind-dispersed aerial conidia ofN. freseniiare infective and rapidly and efficiently disperse the pathogen throughout aphid populations within and between fields.     

Experimental central nervous system phaeohyphomycosis following intranasal inoculation of Xylohypha bantiana in cortisone-treated mice

Experimental central nervous system (CNS) phaeohyphomycosis was established in cortisone-treated mice following intranasal exposure to conidia of Xylohypha bantiana (Cladosporium bantianum, C. trichoides). X. bantiana was recovered from the lungs of 78% of intranasally inoculated normal mice sacrificed within the first 3 days of infection and from 15% at day 28. The fungus was not recovered from the brains of normal mice. In contrast, X. bantiana was recovered from only 33% of the lungs of cortisone-treated mice within the first 3 days of infection. However, the fungus was recovered from the brains of 11% of cortisone-treated mice sacrificed or dying over a 28 day period. Histologically and temporally the CNS disease in cortisone-treated, intranasally inoculated mice was consistent with hematogenous dissemination from a primary pulmonary focus.     

Airborne Aspergillus fumigatus conidia: a risk factor for aspergillosis

Aspergillus fumigatus is an opportunistic fungal pathogen that causes invasive aspergillosis, a usually fatal infection. The disease has risen in prominence in recent years due to the increasing numbers of severely immunocompromised patients becoming infected. The fungus is ubiquitous in the environment, producing large numbers of conidia that are dispersed in the air. Humans inhale numerous conidia everyday, but infections are not seen in healthy individuals. As inhalation of conidia is the main route of infection, considerable efforts are required to prevent infection in susceptible patients. This review summarises the current knowledge on airborne concentrations of A. fumigatus conidia, their background levels in outdoor air and seasonal distribution patterns. New and established methods of air sampling for airborne A. fumigatus conidia are discussed. Common environmental sources of the fungus are reviewed, including its presence in compost heaps. Finally, the lack of stringent guidelines on the monitoring and control of airborne A. fumigatus concentrations in hospitals is discussed.     

Production of TMC-151, TMC-154 and TMC-171, a new class of antibiotics, is specific to ‘Gliocladium roseum’ group

A novel class of fungal metabolites, TMC-151, TMC-154, and TMC-171 series compounds, was found exclusively inGliocladium catenulatum, Clonostachys rosea and closely related strains. These compounds were not detected in any other fungi examined. The production spectrum of each component was correlated to the morphology of the secondary conidiophores and the conidia. TMC-151 was limited toClonostachys rosea (formerlyG. roseum) forming navicular or reniform conidia orG. catenulatum with gray-green conidial masses, whereas TMC-154 and 171 were limited to the strains closely related toGliocladium roseum, which grew more slowly and formed more symmetrical conidia.     

Susceptibility of Larvae of Galleria mellonella to Infection by Aspergillus fumigatus is Dependent upon Stage of Conidial Germination

The ability of conidia of the human pathogenic fungus Aspergillus fumigatus to kill larvae of the insect Galleria mellonella was investigated. Conidia at different stages of the germination process displayed variations in their virulence as measured using the Galleria infection model. Non-germinating (‘resting’) conidia were avirulent except when an inoculation density of 1 × 10⁷ conidia per insect was used. Conidia that had been induced to commence the germination process by pre-culturing in growth medium for 3 h were capable of killing larvae at densities of 1 × 10⁶ and 1 × 10⁷ per insect. An inoculation density of 1 × 10⁵ conidia per insect remained avirulent. Conidia in the outgrowth phase of germination (characterised as the formation of a germ tube) were the most virulent and were capable of killing 100% of larvae after 5 or 24 h when 1 × 10⁷ or 1 × 10⁶ conidia, that had been allowed to germinate for 24 h, were used. Examination of the response of insect haemocytes to conidia at different stages of the germination process established that haemocytes could engulf non-germinating conidia and those in the early stages of the germination process but that conidia, which had reached the outgrowth stages of germination were not phagocytosed. The results presented here indicate that haemocytes of G. mellonella are capable of phagocytosing A. fumigatus conidia less than 3.0 μm in diameter but that conidia greater than this are too large to be engulfed. The virulence of A. fumigatus in G. mellonella larvae can be ascertained within 60–90 h if infection densities of 1 × 10⁶ or 1 × 10⁷ activated conidia (pre-incubated for 2–3 h) per insect are employed.     

Morphological Alterations of Metarhizium anisopliae During Penetration of Boophilus microplus Ticks

Chronological histological alterations of Metarhizium anisopliae during interaction with the cattle tick Boophilus microplus were investigated by light and scanning electron microscopy. M. anisopliae invades B. microplus by a process which involves adhesion of conidia to the cuticle, conidia germination, formation of appressoria and penetration through the cuticle. Twenty-four hours post-infection conidia are adhered and germination starts on the surface of the tick. At this time, the conidia differentiate to form appressoria exerting mechanical pressure and trigger hydrolytic enzyme secretion leading to penetration. Massive penetration is observed 72 h post-inoculation, and after 96 h, the hyphae start to emerge from the cuticle surface to form conidia. The intense invasion of adjacent tissues by hyphae was observed by light microscopy, confirming the ability of M. anisopliae to produce significant morphological alterations in the cuticle, and its infective effectiveness in B. microplus.     

A new species of <Emphasis Type="Italic">Discostroma</Emphasis> and its anamorph <Emphasis Type="Italic">Seimatosporium</Emphasis> with two morphological types of conidia,isolated from the stems of <Emphasis Type="Italic">Paeonia suffruticosa</Emphasis>

Conidia of two morphologically different types, one with a basal appendage only and the other with appendage at both ends, were isolated from the stems of Paeonia suffruticosa. Single conidial isolates of both types of conidia yield identical colonies, which then produced both types of conidia on agar media depending on temperature, thus showing that both types of conidia belong to the same fungus. Seimatosporium botan is described based on its morphological characteristics. The teleomorph of the fungus was first found on sterilized P. suffruticosa stems placed on water agar, when grown at 5°C for 2 months in 12-h photoperiod. Discostroma botan is described for this fungus. The teleomorph is also found on the same host in the field.     

Evaluation of the potential role of water in spread of conidia of the Neotyphodium endophyte of Poa ampla

Neotyphodium endophytes are asexual, filamentous fungi, mutualistically associated with diverse cool season grasses. Infected seeds and vegetative organs of infected host plants are the only known modes of propagation of the asexual endophytes. In the last decade certain Epichloë and Neotyphodium-infected grass species have been shown to have epiphyllous structures of the endophytes, hyphae, conidiophores, and conidia, growing on leaf blades. The production of epiphyllous conidia suggests the possibility that some of these endophytes may have the ability for plant-to-plant spread. The objective of this study was to determine the possible mechanisms involved in liberation and dispersal of asexual spores of Neotyphodium growing in vitro and epiphyllously on leaves of Poa ampla. Our results indicate that water dispersal is the most likely means of dissemination of conidia of the Neotyphodium sp. Wind generated by dry compressed air does not dislodge the conidia from slide cultures or from P. ampla leaves.     

Infectivity of two members of theEntomophthora muscae complex [Zygomycetes: Entomophthorales] forMusca domestica [Dipt.: Muscidae]

Dose-mortality studies were conducted with 2 members of theEntomophthora muscae (Cohn) Fresenius complex from southern California (CA) and Denmark (DA) infecting house flies,Musca domestica L., from southern California. Primary conidia of the DA form were significantly more infective (LC₅₀=34 conidia/mm²) than primary conidia of the CA form (LC₅₀=67 conidia/mm²) for 2–7 days old (‘young’) flies. Infectivity (single experimental trial) for 10–14 day old (‘old’) flies of primary conidia of the CA form (LC₅₀=34 conidia/mm²) was similar to that of the DA form for young flies. Secondary conidia of the CA form were markedly more infective (LC₅₀=0.36 conidia/mm²) than primary conidia of either form. Dose had no significant effect on incubation period for primary conidia of either form, but increased doses resulted in significantly shorter incubation periods for flies exposed to secondary conidia of the CA form.      

Fusarium nisikadoi, a new species from Japan

A new species ofFusarium, F. nisikadoi, isolated fromPhyllostachys nigra var.henonis (bamboo) andTriticum aestivum (wheat) in Japan, is described, illustrated and discussed. This species is differentiated from other known species of the genus by the following characteristics: whitish colony color, long zigzag-like chains of 0–3(-5)-septate clavate conidia, intermixed with pyriform conidia, produced mostly from monophialides and rarely from polyphialides in the aerial mycelium, very long and slender sporodochial conidia, and no chlamydospores. The long chains of septate conidia are known only in this species of the genusFusarium. The conidiophores on the aerial mycelium sometimes proliferate sympodially. The species is tentatively placed in the form-sectionLiseola.     

Multinucleation in the conidia of polyploids derived fromTrichoderma reesei QM 9414 by colchicine treatment

Conidia ofTrichoderma reesei QM 9414 were treated with colchicine in order to obtain polyploids (diploids; tetraploids). Cellulase production by diploids (mononucleate conidia) was almost twice as great as that of the original strain, but that of tetraploids (binucleate conidia) was not increased. When these latter conidia were re-treated with 2.0% (w/v) colchicine, multiple nuclei were produced in each conidium, and their diameter was almost the same as that of the original nucleus. Cellulase production of the diploid was almost the same in either mononucleate or multinucleate nature. However, cellulase production by the tetraploid which produced multinucleate conidia was greater than that of the binucleate tetraploid and that of the diploid. The multinucleation technique can contribute to enhancing cellulase production.     

Resistance of the termite, <Emphasis Type="Italic">Coptotermes formosanus</Emphasis> Shiraki to <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> due to grooming

Termites, Coptotermes formosanus, reared individually, were highly susceptible to the entomopathogenic fungus, Metarhizium anisopliae, while termites reared in␣groups were highly resistant. When reared in groups, the termites treated with M.␣anisopliae conidia on the body surface were groomed by their nestmates and more than 80% of the conidia were removed from the cuticle within 3 h. However, there was not a significant reduction in the numbers of conidia on the body surfaces of termites reared individually. For the termites maintained in groups, conidia were found in foreguts, midguts and hindguts, but very few conidia were detected in the guts of termites reared individually. Conidia in the alimentary tracts did not germinate, but some of were alive. As a result, it seems that the removal of foreign bodies, such as fungal conidia, from the␣cuticle is one function of termite mutual grooming behavior and that conidia removed from the cuticle are eliminated through alimentary tracts. This study indicates that mutual grooming behavior is very effective in protecting these termites from M.␣anisopliae infection.     

Effects of extracts of fiberglass insulations on the growth ofAspergillus fumigatus andA. versicolor

Water extracts of thermal and acoustic fiberglass insulations used in the duct work of heating, ventilation and air conditioning (HVAC) systems supported germination of conidia and growth ofAspergillus versicolor (Vuillemin) Tiraboschi 1908–9 andAspergillus fumigatus Fresenius 1863. Urea, formaldehyde and unidentified organics were detected in the extracts. Formaldehyde in concentrations similar to those found in the extracts restricted the growth of both species in enriched media.A. versicolor, the more common species associated with fiberglass insulations, was more resistant to formaldehyde thanA. fumigatus.     

Five additional genera of conidial lichen-forming fungi from Europe

Three remarkable new genera of conidial lichen-forming fungi, with pycnidial or acervular conidiomata are described and illustrated.Hastifera tenuispora gen. et spec. nov. from the South-Tyrol, Italy, is characterized by very long and narrow hyaline conidia produced in pycnidial conidiomata immersed in thalline warts.Lichingoldia gyalectiformis gen. et spec. nov. from rocks subject to inundation by freshwater in Norway has long sigmoidly curved conidia which appear to be adapted to dispersal in water.Woessia fusarioides gen. et spec. nov. from aQuercus stump in the Burgenland, Austria, has a finely granular thallus and disc-like conidiomata producing falcate conidia; this species is also of interest in that it hasChlorella as the photobiont. The recently described hyphomyceteCheiromycina flabelliformis B. Sutton is reported from Austria for the first time, and is also lichenized. Recent collections ofNigropuncta rugulosa D. Hawksw. from Austria and Italy also show that this species is lichenized rather than parasymbiotic. In all five cases the fungal hyphae of the conidiogenous structures are continuous with those in intimate contact with cells of the algal partners and the biological relationship appears to be mutualistic giving rise to stable crustose lichen thalli.     

Morphology and phylogeny of <Emphasis Type="Italic">Botryosphaeria dothidea</Emphasis> causing fruit rot of olives

The taxonomic position of the causal agent of fruit rot of olives was determined from fresh collections of the fungus from central Greece. In culture it formed two types of conidia, namely fusiform, hyaline, aseptate conidia typical of the genus Fusicoccum, and dark-walled, ovoid, ellipsoid or fusiform, 1–2 septate conidia that are not typically observed in Fusicoccum. A phylogenetic analysis based on ITS and EF1- sequences placed the fungus within the same clade as Fusicoccum aesculi, which is the anamorph of Botryosphaeria dothidea, and the type of the genus Fusicoccum.     

Materials for the fungus flora of Japan (56)Mariannaea camptospora andM. elegans var.punicea from Japan

One additional species and a variety ofMariannaea, M. camptospora andM. elegans var.punicea, were recorded for the first time in Japan.Mariannaea camptospora formed two types of conidiophores. One type was characterized by simple verticillate phialides sometimes with punctuate walls at the base, producing long oblique conidial chains, and symmetrical spindle-shaped conidia. The other type was characterized by more crowded and shorter phialides with small conidial droplets and hemispherical to concave smaller conidia.Mariannaea elegans var.punicea was characterized by distinct red purple pigmentation in agar media. (55): Udagawa, S. and Uchiyama, S., Mycoscience41: 263–267, 2000.     

Pathogenicity, formulation and storage of insect pathogenic hyphomycetous fungi tested against Diabrotica speciosa

Studies were conducted tosearch for fungal strains with potentialpathogenicity against Diabrotica speciosa(Germar) (Coleoptera: Chrysomelidae).Among sixteen fungal isolates screenedthe most virulent was a Beauveria bassiana(Balsamo) Vuillemin isolate (FHD13) thatcaused 70% mortality of D. speciosathird instar larvae. The LC₅₀ value ofB. bassiana isolate FHD13 was3.48 × 10¹⁰ conidia/ml.Different temperatures (4, 17 and 26 °C)and vegetable oils (corn, sunflower and canola)used for storage did not significantly affectviability of conidia. A pathogenicity trialagainst D. speciosa larvae performed withthe corn oil formulation (1 × 10⁸ conidia/mlof oil) caused 65% of mortality.     

Airborne fungal spores and the thunderstorm of 24 June 1994

On the evening of 24 June 1994 there were thunderstorms which passed from the south to the north over large areas of England, followed by an extensive and initially alarming episode of 'thunderstorm asthma'. It was eventually concluded that the probable cause of this episode was the release of allergenic particles from wetted grass pollen. As part of the investigation of this episode changes in the fungal air spora were investigated at several sites. The fungal spores present varied from site to site. At London, Addlestone and Leicester there were very marked transient peaks of smut ustilospores (and to a much smaller extent at Cambridge), particularly those of Ustilago segetum (Bull.) Roussel. At many sites there were transient peaks of Cladosporium conidia. The possible causes of the transient peaks are discussed. At most of the other sites except London there were high concentrations of ascospores after the rain. Typically, Didymella ascospores occur after rain, but on this occasion they occurred at low concentrations at all sites, because of dry weather in the previous month. Instead, there were high concentrations of ascospores which normally occur in far lower numbers, viz. ascospores of Phaeosphaeria nigrans and Diatrypaceous ascospores. The reasons for this were related to increased rainfall in the previous thirteen months. There were site to site differences in the ascospore composition of the air spora, and this was related to habitat differences, where this was known. This revised version was published online in June 2006 with corrections to the Cover Date.     

Brown spot ofRheum officinale in indonesia with special reference to the variation in conidia of the causal fungus

Brown spot disease ofRheum officinale, a traditional medicinal plant in South East Asia, was newly recorded from the highland area of West Java Province. After confirmation of its pathogenicity towardRheum officinale and comparison of its morphology with hitherto known species, the casual fungus was identified asAscochyta rhei. It produces widely varied conidia from unicellular and bacillar conidia (Phoma-type), 1-septate oblong conidia (Ascochyta-type) to 2–3-septate cylindric conidia. These conidia were sometimes formed within the same pycnidium. They could germinate easily and produce the similar colonies to each other. Supported by “Joint Study Project for Strengthening Research on Diseases of Industrial Crops in Indonesia, Japan International Cooperation Agency (JICA)” in BALITTRO.