The biological relationships of lichenicolous fungi and their hosts are studied in four members of the Dacampiaceae. Infections of the lichenicolous species Dacampia engeliana induce in its host Solorina a thallus morphology similar to that found in the lichenized D. hookeri. D. engeliana, however, differs microscopically by hyphae growing inside those of Solorina in the algal layer and the medulla. Pyrenidium actinellum develops short haustorial structures into the hyphae of the host. These haustoria are characterised by finger-like outgrowths into the host cells. Clypeococcum hypocenomycis forms dense brown mycelia in the upper cortex of the host, which is progressively destroyed. These lichenicolous parasites have a preference for the fungal symbiont of the host lichen and, in contrast to several other lichenicolous fungi, the algal partner is not primarily affected. The various types of infection modes found in the family Dacampiaceae suggest that a great variation of infection modes may exist in further groups of lichenicolous fungi. Other infection types are included in the discussion.

Inter- and intra-specific variation in destruxin production was detected in Metarhizium and may be important in determining virulence and/or specificity against insects. Strains of M. anisopliae var. anisopliae produced different amounts of destruxins A, B and E, but strain V220 did not produce any destruxins. M. anisopliae var. majus, M. flavoviride and M. album which are reported to be specific towards Coleoptera, Orthoptera and Hemiptera, respectively, had different destruxin profiles with destruxin A predominant. In time course studies on M. anisopliae var. anisopliae V245, destruxin E levels declined with time while destruxin A levels increased. The most virulent strains, Ma23 and V245, produced large quantities of destruxins but some low toxin producers were also virulent, suggesting that destruxins are not the only pathogenicity determinants. Some weakly to moderately pathogenic strains were highly pathogenic when injected into Galleria mellonella larvae, demonstrating the importance of the cuticle as a barrier to fungal infection. Only trace amounts of destruxin A or a combination of A and B could be detected in Galleria larvae infected with M. anisopoliae var. anisopliae or M. anisopliae var. majus. No destruxins were detected in larvae infected with M. flavoviride. Destruxin production may be influenced by the nutrients in insects or culture media.

The infection of wheat spikes by Fusarium culmorum, one of the agents responsible for wheat head blight, was examined by light and electron microscopy. Macroconidia of the pathogen germinated 6–12 h after inoculation on all host surfaces they contacted. Developing germ tubes did not infect host tissues immediately, but gave rise to hyphae that grew and branched on host surfaces. Hyphal networks were usually formed 2 d after inoculation (dpi) on the inner surfaces of lemma, glume and palea, but not on the outer surfaces of lemma, glume and rachis. Hyphae on the outer surfaces of lemma and glume often grew over their edges to reach their inner surfaces. Penetration of host tissues occurred by infection hyphae on the inner surfaces of lemma, glume and palea, and on the upper part of the ovary. Occasionally, the pathogen invaded the host tissues through stomatal openings on the inner surface. Thereafter, the pathogen spread downwards to rachilla and rachis node by inter- and intracellular growth from above infected tissues. From the rachis node, hyphae extended downward to rachis and upward to peduncle through vascular bundles and cortical parenchyma tissue. When the pathogen arrived at the rachis 4–5 dpi, hyphae grew upwards and downwards inter- and intracellularly in vascular bundles and cortical parenchyma tissue of the rachis. During colonisation of the wheat spike, a series of alterations occurred in host tissues, including degeneration of host cytoplasm and organelles, collapse of parenchyma cells, disintegration or digestion of host cell walls and appearance of electron-dense coating materials on vessel walls.

The forest pathogen Dothistroma pini (Scirrhia pini) infects the needles of many pine species, causing needle loss and consequently retarded wood growth. Only one strain of Dothistroma pini is present in New Zealand. Because over 90% of commercial forests in New Zealand are planted with the susceptible species Pinus radiata, a study of the global diversity of D. pini strains was initiated to assess the threat of further unwanted introductions of the pathogen. A collection of D. pini strains from eight countries was studied in the UK. The production of dothistromin toxin by the strains, and DNA sequence analysis of the ribosomal ITS region, confirmed their identification as D. pini, although strains from the central USA contained two nucleotide substitutions in the ITS region. Colony morphologies and growth rates were diverse, but all strains which sporulated showed a similar wide range of spore size. The morphological features examined did not support separation of the strains into the two groups shown by ITS sequences. Most striking was the production, in axenic culture, of extremely high levels of dothistromin toxin by strains from Germany and, to a lesser extent, some from the USA (>500 times and >40 times as much as the New Zealand strain, respectively). The high level of production of dothistromin toxin by some strains is a concern for forest health as well as for forest workers and needs to be evaluated further.

The rust fungus Chrysomyxa woroninii causes perennial witches' brooms on several species of Ledum in northern and subalpine regions of Europe, North America and Asia. Spruce bud rust has been assumed to be the aecial state of C. woroninii because of the close proximity of infected Ledum plants and systemically infected buds on Picea. The lack of experimental evidence for this connection, however, and the presence of other species of Chrysomyxa on the same hosts has led to confusion about the life-cycle of C. woroninii. In this study, infections on both spruce and Ledum were studied in the field and in a greenhouse. The link between the two states was proven by inoculating spruce with basidiospores from Ledum groenlandicum. After infection of spruce in spring, probably through the needles, the fungus overwinters in the unopened buds until the next spring, when the infected shoots are distinguished by stunting and yellow or red discolouration. Microscopic examination of dormant Ledum shoots showed that C. woroninii overwinters in this host in the bracts and outer leaves of the vegetative buds, and in the pith and cortex of the stem. The telia of C. woroninii, on systemically infected Ledum leaves of the current season, are easily distinguished from the telia of other Chrysomyxa species on the same hosts. The latter produce localized telia and uredinia only on overwintered leaves, produce aecia on spruce needles in the same year as infection occurs, and are not systemic in spruce. The restricted habitat distribution of C. woroninii and the need for overwintering outdoors suggest that this rust fungus has specific environmental requirements for survival.

Isozymes of five Australian Ganoderma species were studied using cellulose acetate gel electrophoresis (CAGE) and PAGE. Phenetic analysis supported the distinction between the five species, which were separated by unbiased genetic distances of between 0.532 and 3.330. Estimates of heterozygosity and polymorphisms identified considerable genetic variability within populations and species. The putative saprotrophic G. australe, G. incrassatum and G. cupreum had the lowest genetic variability while the pathogen Ganoderma sp. Group 6.3, morphologically similar to G. lucidum, had the highest, followed by G. weberianum. Isolates of G. adspersum, G. applanatum from Europe and G. australe from Australia differed at most loci, thus the commonly accepted synonymy between G. australe and G. adspersum was not supported. Pectic isozymes alone were sufficient to distinguish three laccate (possessing a cutis surface consisting of a palisade of inflated hyphal ends) Australian species, G. weberianum, Ganoderma sp. Group 6.3 and G. cupreum, but they did not distinguish between the non-laccate G. australe and G. incrassatum. The laccate group contains species of greatest economic importance. Australian species were resolved by a single isozyme (glucose-6-phosphate dehydrogenase) using CAGE, demonstrating the potential for this method as a rapid diagnostic tool for identifying species of Ganoderma. This is the first reported population genetics based study of Ganoderma using isozymes.

Four halophytes belonging to three dicotyledon families, Acanthaceae, Aizoaceae and Chenopodiaceae, were screened for the presence of fungal endophytes. Thirty-six species of fungi, including some sterile forms, were isolated. Camarosporium species showed some degree of host preference as they were the dominant endophytes of the halophytes of Chenopodiaceae but were absent from the other halophytes. Some genera such as Colletotrichum, Phomopsis, Phyllosticta and Sporormiella were ubiquitous.

Phialocephala fortinii is a common root endophytic fungus with a wide geographic distribution and little, if any, host specificity. Little is known about its habitat specificity, although there is evidence to suggest that high water tables may restrict the occurrence of P. fortinii in wetlands. We tested this hypothesis by determining the distribution of P. fortinii along a sand dune – wetland complex. Isolates of P. fortinii, identified on the basis of cultural and morphological characteristics, were obtained from the roots of vascular plants across the moisture gradient. Three ‘cultural groups’ were recognized among these isolates. Thirty-three of these isolates were compared among themselves and to strains of known identity using PCR/RFLP analysis of the ITS region and a portion of the 28S subunit of rDNA. The restriction digest profiles of all isolates were identical to those of P. fortinii for 4 restriction enzymes. DNA sequences, from a subset of these strains, showed a low percent sequence divergence confirming the reliability of the RFLP data. The same analyses were done with two strains of Leptodontidium orchidicola, a culturally similar root endophyte, to ensure that this taxon was not among the transect isolates. DNA data showed a clear difference between P. fortinii and L. orchidicola but did not discriminate among cultural groups. Thus, P. fortinii showed no habitat specificity and occurred in both xeric and hydric sites. RFLP profiles and ITS sequences showed little variation among isolates of P. fortinii and among the isolates of L. orchidicola.

The cultivation and competitiveness of Tuber borchii was investigated. Seedlings of Pinus pinea were infected either with T. borchii, Laccaria bicolor (strain S238), Hebeloma sinapizans, T. borchii and L. bicolor, or T. borchii and H. sinapizans. Uninoculated seedlings weakly infected with Sphaerosporella brunnea were used as controls. In 1990 the seedlings were transplanted to a coastal site at Marina di Ravenna, Italy. Examination of seedling roots in 1994 and 1995 showed that L. bicolor, H. sinapizans and S. brunnea ectomycorrhizas were replaced by T. borchii and other ectomycorrhizal fungi. The DNA sequence of the ITS region was analysed using the specific pair of primers, ITS1–ITS4, to type the ectomycorrhizas of Tuber borchii. The ectomycorrhizas were also identified by digestion of the PCR products using different restriction enzymes. T. borchii truffle production began in 1994 and for the next four years an average of 7 kg of truffles ha−1 were harvested. This study describes a simple method for the cultivation of T. borchii.

A mechanism is proposed for the creation of taenia on the capillitium of Trichiales. Polymerization of elater wall material forms spiralling fibrils, releasing water which passes by osmosis into the lumen. This extends the bulbous extremities of Trichia decipiens elaters producing the characteristically tapered tips. The edge of the elater shrinks as water is lost, and is moulded by the fibrils into a system of taenia.

In the field, the concentrations of several soluble carbohydrates in mycorrhizas of red pine varied seasonally. Fructose, glucose, sucrose and trehalose concentrations were negatively correlated with soil temperature, while myo-inositol and mannitol concentrations were positively correlated. The patterns for the concentrations of fungal carbohydrates (trehalose and mannitol) were consistent with their previously-reported functions. Trehalose may serve as a storage carbohydrate, accumulating during the winter when host carbohydrate is plentiful and when fungal growth is reduced. In contrast, mannitol may serve a translocatory role, increasing in concentration in warmer months when fungal growth is more rapid and when sporocarps are formed.

The carbohydrates of six species of ectomycorrhizal fungi grown at room temperature and at reduced temperatures were also analysed to determine the extent to which seasonal variation in concentrations of fungal carbohydrates of mycorrhizas may be due to fungal acclimation to temperature. Variation in carbohydrate concentration occurred both among fungal species and due to cooling treatment. The variation due to cooling was relatively small, generally less than the variation among species, and less than the seasonal variation observed in field-collected mycorrhizas. This suggests that seasonal variation in the fungal carbohydrate trehalose in mycorrhizas could possibly be due to shifts in host carbohydrate supply rather than to independent shifts by the fungi in response to temperature. Production of a distinct pattern of carbohydrate concentrations by different ectomycorrhizal fungi suggests that fungal carbohydrates may be of taxonomic significance. This was further demonstrated using discriminant analysis of fungal carbohydrates.

The ITS of the nuclear ribosomal DNA of Serpula lacrymans and S. himantioides was amplified by PCR to evaluate this DNA region as a diagnostic tool. Sequencing of the amplified ITS region revealed a size of the complete ITS of 654 bp for S. lacrymans and 650 bp for S. himantioides. The base sequence difference between the two fungi was used to design species-specific oligonucleotide PCR primers for both species. With laboratory and field samples, each primer selectively detected its target organism. No cross reaction occurred with other fungi causing rot of indoor wood.

This paper synthesizes the work done on decolourization of bleach plant effluent and synthetic dyes using fungi from marine habitats. Three fungi obtained from marine habitats removed up to 60–95% of Kraft paper mill bleach plant effluent colour. One of the cultures could bring about decolourization of bleach plant effluent at an alkaline pH of 8.2. All the three fungi produced the lignin-modifying enzymes laccase and manganese-dependent peroxidase (MNP) and one of the cultures, Flavodon flavus (isolate 312), also produced lignin peroxidase (LIP) when grown in low nitrogen medium. Production of these enzymes increased in the presence of paper mill effluent in all the three isolates. Isolate Flavodon flavus (312) decolourized synthetic dyes like Azure B, Brilliant green, Congo red, Crystal violet, Poly-R, Poly-B and Remazol Brilliant Blue R in low nitrogen medium prepared with distilled as well as with artificial sea water. Decolourization of dyes was also observed in a rich nutrient medium like malt extract broth. About 60–90% of decolourization was achieved in these media within 3–10 days. Visible spectra of most of the dyes incubated with this culture indicated degradation at the end of the experiment. Manganese-dependent peroxidase enzyme was always produced in cultures of 312 containing dyes and in some cases, a direct correlation existed between % decolourization and MNP activity, suggesting its involvement in this process. This culture with its capacity to degrade paper mill effluent and synthetic dyes appears to be a potential candidate for bioremediation of coloured industrial effluents.

An investigation was conducted into whether fungal dynamics are determined by the balance between colonization and fructification, both of which are controlled by climatic factors, particularly rainfall. The distribution of Lophodermium pinastri on Pinus sylvestris needles was studied along two altitude transects over two successive years. Annual rainfall increased in a similar way along the two transects. Colonization (black zones) and the presence of fruiting bodies (ascomata and/ or conidiomata) were observed. Both increased with altitude. At low altitude, needles bore black lines only. The number of needles bearing fruiting bodies increased at altitudes above 1000 m and were present on all needles at high altitude. Empirical and dynamic mathematical models were developed and evaluated in relation to rainfall, assuming that spore production correlates with fructification, and colonization to spore dispersal.

Acervuli of E. mespili developed subcuticularly on both surfaces of infected Photinia leaves. Acervuli developed as single or aggregated, confluent structures. Conidium initials arose from hyphae which developed between the cuticle and epidermis. As conidia developed the cuticle was displaced and eventually ruptured. Development of the first conidium from a conidiogenous cell was holoblastic. Subsequent conidia developed in an enteroblastic, annellidic fashion. Three to four conidia arose from a single conidiogenous cell. A mature conidium consisted of four to six cells including an apical cell and a basal cell which developed first. These were separated by a septum with a plugged pore. A similar septum separated the basal cell from the conidiogenous cell. A long, slender, enucleate appendage then arose from the tip of the apical cell. During this time the basal cell gave rise to two to four small lateral cells, separated by septa from the basal cell. An appendage then developed from each lateral cell. Each cell of a mature conidium contained a single nucleus and a complement of cytoplasmic organelles and inclusions, many of which were more prominent in freeze substituted conidia than in chemically fixed conidia. The conidium wall labelled for chitin using wheat germ agglutin-gold conjugate. Its outer surface was coated with fibrillar material.

The capacities of 24 decay fungi, isolated from living trees and decayed timber of the East African camphor tree, to colonise sapwood and heartwood of living trees was tested. Eight species colonised sapwood, and five colonised heartwood and were viable 12 months after inoculation. It was noteworthy that eight important decay species of the East African camphor timber, including Phellinus senex, which is the dominant heartrot species, failed to invade tissues of living trees. The implications of these findings are discussed in relation to the water content and pH of infected and non-infected tissues as well as some parameters of growth of colonised trees.

Four isolates of the entomopathogenic fungus Erynia neoaphidis, from different hosts and locations in Switzerland, were distinguished by their DNA fragment banding pattern obtained by RAPD–PCR. The isolates differed in sporulation and germination rates, but not in virulence (overall mean LD50 16 conidia mm−2) against the aphid Acyrthosiphon pisum. The sporulation rate was 6 to 24 conidia mm−2 10 min−1. On nutrient agar, 24–73% of the conidia produced secondary conidia and 32–68% produced germ-tubes on polystyrene. Differentiation of primary into secondary conidia or germ-tubes is possibly dependent on the presence of free water on the contact surface; on a dry surface, conidia germinated mostly with a germ-tube, whereas on a wet surface the conidia produced a secondary conidium. Experimental support is provided for the claim that, in addition to LD50 values, features such as sporulation rate, spore germination, capacity to form secondary conidia and intraspecific variation should be considered in selecting isolates of E. neoaphidis for biocontrol agents.

Several isolates of the entomopathogenic Metarhizium anisopliae that harboured dsRNA viruses of similar electrophoretic band sizes (1.8 and 2.0 kbp) were assessed for homologies of the dsRNA by Northern analysis. The isolates were also characterised genetically by RAPD and VCG. Similarly sized dsRNA, as visualised by electrophoresis, were not always homologous, suggesting that the comparison of dsRNA based solely on electrophoretic banding patterns is an unreliable method of dsRNA characterisation. Several isolates, but not all, harbouring multiple dsRNA patterns, including a 1.8 and 2.0 kbp doublet, also showed homologies to strains harbouring only the dsRNA banding doublet. This suggests that mixed infections of different dsRNA elements are found in M. anisopliae. Genetically similar fungi, based on RAPD banding patterns and vegetative compatibility, were more likely to harbour genetically related dsRNA. The findings suggested that dsRNA elements in M. anisopliae are horizontally transferred to genetically related isolates or are maintained through clonal lineages.

Chitin synthase genes of Tuber magnatum were sought in order to investigate the molecular bases of its growth. Primers designed from highly conserved Chs domains were used to identify a chs gene portion. A genomic library was used to obtain the full gene sequence (TMchs4) with an open reading frame which encodes a predicted protein of 1230 amino acids. The sequence is similar (62%) to the class IV chitin synthase from Neurospora crassa. The putative protein shows hydrophobicity pattern that suggests the presence of several intramembranous domains and other peculiar features common to the other chs of class IV. Northern experiments demonstrated that the gene is expressed in ascomata sampled at different maturation steps. These data suggest that ascomata growth requires new chitin deposition, which is based on a chs gene activation and not only on an enzymatic activity.

A study was designed to isolate and identify the endophytic mycobiota in leaves and twigs of Rubus spectabilis and R. parviflorus, the long-term goal being biological control of these plants with endophytes. Endophytic fungi were isolated from healthy-looking leaves and twigs collected from each species on Vancouver Island, British Columbia, Canada. More than 90% of the leaves of both species were colonised by endophytes. In addition, one third of the twig samples of each species were also colonised. Most isolates belonged to Phomopsis, and five species were identified and characterised according to morphology of the cultures and fructification structures. All Phomopsis species occurred on both Rubus species, but, one primarily colonised R. parviflorus, whereas another preferentially colonised R. spectabilis. The suitability of the isolated endophytes to inhibit growth of R. spectabilis and R. parviflorus, which compete with conifers in reforestation sites, is discussed.