This issue of Mycological Research News features: Confusion over Amanita pantherina in Japan; Foliicolous lichens are benign; A plethora of bryophilous niches; and A longevity gene in Saccharomyces.

Fast-tracked for publication in this issue is the description of another new species of pathogenic Phytophthora, attacking deciduous trees in Europe. Specific primers for the detection of Pythium oligandrum in mushroom beds have been developed and tested. Puccinia tanaceti is shown to be more host-restricted than supposed. Transformation systems for Venturia inaequalis are compared, and the separation of Fusarium species causing crown and head blight of cereals, and also of Vericillium dahliae and V. tricorpus is described.

The genetic basis of Aspergillus parasiticus strains that do not form aflatoxins has been explored, and large insert had been found in an aflatoxin-producing A. flavus strain. Two genes involved in the early stage of melanin production in Colletotrichum lagenarium are reported, and pairing tests in Helocobasidium mompa show it to have a single incompatability factor. Strategies adopted for growth in toxic metal environments have been studied and factors affecting growth determined. Conditions to optimise growth in entomophthoralean fungi have been explored, the coffee berry borer in Mexico has been found to support a wider range of fungi than hitherto expected, and a new Monacrosporium able to trap nematodes as well as to parasitize fungal sclerotia has been discovered.

The following new scientific names are introduced in this part: Monacrosporium janus, and Phytophthora pseudosyringiae spp. nov.

In several studies of oak decline in Europe, a semi-papillate homothallic Phytophthora taxon was consistently isolated, together with other Phytophthora species, from rhizosphere soil samples. It was also found associated with necrotic fine roots and stem necroses of Fagus sylvatica and Alnus glutinosa. Due to morphological and physiological similarities, the semi-papillate isolates were previously identified as P. syringae by various authors. The morphology, physiology and pathogenicity against fine roots of Quercus robur, Q. petraea and F. sylvatica, bark of A. glutinosa, leaves of Ilex aquifolium and apple fruits of this Phytophthora species are described and compared with those of related and similar Phytophthora species, namely P. ilicis, P. psychrophila, P. quercina, P. citricola and P. syringae. The phylogenetic placement on the basis of ITS and mtDNA sequence data was also examined. Isolates of this taxon produce colonies with stellate to rosaceous growth patterns and limited aerial mycelium on various agar media. Antheridia are predominantly paragynous. In water culture catenulate hyphal swellings and semi-papillate caducous sporangia, that are usually limoniform, ellipsoid or ovoid, are formed abundandly, mostly in lax or dense sympodia. This taxon is a moderately slow growing, low temperature species with optimum and maximum temperatures around 20 and 25 °C, respectively. Tested isolates are moderately aggressive to fine roots of oaks and beech, highly aggressive to holly leaves and apple fruits, and slightly pathogenic to alder bark. Thirteen tested isolates had an identical and distinct ITS sequence which was more similar to that of P. ilicis and P. psychrophila than any other known taxa. On the basis of their unique combination of morphological characters, colony growth patterns, cardinal temperatures for growth, growth rates, pathogenicity to oaks, beech, alder, apple and holly, their host range, and ITS and mtDNA sequences the semi-papillate caducous Phytophthora isolates from oaks, beech and alder are clearly separated from related and similar Phytophthora spp., and described as a new species, P. pseudosyringae sp. nov.

Pythium oligandrum is a parasite of cultivated Agaricus bisporus. Infection results in significant yield reductions and a disease referred to as ‘black compost’. In this study, P. oligandrum isolates were isolated from New Zealand mushroom composts, and their ribosomal DNA internal transcribed spacer (ITS) regions were amplified using the polymerase chain reaction (PCR). ITS nucleotide sequences obtained from New Zealand P. oligandrum isolates were compared with those previously identified P. oligandrum isolates and 23 described Pythium species. Although New Zealand P. oligandrum isolates had high ITS nucleotide identity with internationally identified P. oligandrum, the order of nucleotides in some regions varied when compared with other Pythium species. These varied nucleotides within the ITS region were used to design PCR primers (P.OLIG.F1 and P.OLIG.R04) for the specific amplification of a 384-bp fragment from P. oligandrum DNA. P.OLIG.F1 and P.OLIG.R04 were used to identify a major source of P. oligandrum inoculation on a New Zealand mushroom farm. Application of this diagnostic test will assist farming strategies implemented to prevent future P. oligandrum outbreaks. Furthermore, results presented identify a need for species resolution between P. oligandrum and P. hydnosporum.

Rust is reported for the first time in North America on tansy (Tanacetum vulgare), a widespread and invasive Eurasian plant that was introduced into North America in the 17th century. Morphologically, the rust fungus corresponds exactly to Gäumann's description of Puccinia tanaceti, and to European specimens of P. tanaceti on T. vulgare. An inoculation study confirmed the narrow host specialization of P. tanaceti that Gäumann described, in that T. vulgare was successfully inoculated whereas four other species of the tribe Anthemidae of the Asteraceae were entirely resistant, i.e. Leucanthemum maximum (Shasta daisy), L. vulgare (ox-eye daisy), Artemisia absinthium (wormwood), and A. tridentata (sagebrush). This confirmation of a specialized P. tanaceti invalidates P. tanaceti s. lat. The latter complex has resulted from synonymies, and compilation of host records of rust fungi resembling P. tanaceti on at least 105 species representing 19 genera from six tribes of the Asteraceae from both New and Old Worlds.

We report the development of two new transformation systems, polyethylene glycol (PEG)-mediated transformation of protoplasts and Agrobacterium tumefaciens-mediated transformation of mycelium, for the filamentous ascomycete Venturia inaequalis. New binary vectors have been created for the latter. Although transformation was initially achieved using a PEG-mediated method, this was superseded by the A. tumefaciens-mediated approach. The advantages of the latter include: ease of the protocol, no requirement for protoplasts; higher transformation efficiency; and single-site integration. A comparison between the two transformation methods is presented.

Genetic relationships of the complex of Fusarium species associated with crown rot and head blight in cereals and some species associated with plant diseases in general were examined by distance and maximum parsimony algorithms of their internal transcribed spacer sequences. The analysis clustered the complex of Fusarium species that causes root and crown rot and head blight of cereals and three other clusters of F. sambucinum, F. venenatum and F. poae into one clade. This group of Fusarium species was also found in this study to correspond to the group defined by the presence of the tri5 gene. The tri5 gene was recently reported to co-segregate with the locus governing the type of trichothecene produced, and probably maps in the trichothecene gene cluster. The other clusters of F. avenaceum, F. tricinctum, F. torulosum, F. oxysporum, F. verticillioides and F. solani did not have the tri5 gene. Although, F. pseudograminearum was phylogenetically close with the cluster of F. graminearum, F. culmorum and F. cerealis, it could be distinctly separated from them. The distinct genetic status of F. pseudograminearum from F. graminearum corroborated with other published molecular data and isozyme findings. The molecular analysis provided a simple diagnostic tool to differentiate fungi causing crown rot from those involved in head blight.

The morphology of two soil-borne Verticillium species, V. dahliae and V. tricorpus, was studied on two semi-selective agar media, in the absence and presence of soil. Morphology of the fungi differed considerably between the media, with respect to presence and shape of microsclerotia, dark hyphae (i.e. short melanised hyphae attached to the microsclerotia) and dark mycelium (i.e. melanised mycelium throughout the colony). On modified soil extract agar (MSEA), a pectate based agar, V. dahliae always had globose to elongate microsclerotia, without dark hyphae or dark mycelium, whereas V. tricorpus always had dark hyphae or dark mycelium, and microsclerotia, whenever present, were globose to irregular in shape. On ethanol agar (EA), V. dahliae had large microsclerotia and abundant dark hyphae, whereas V. tricorpus did not form microsclerotia, but always abundant dark mycelium. For the first time we observed the formation of dark hyphae by V. dahliae to a great extent. In the presence of soil, most characteristics were less pronounced, and V. dahliae microsclerotia were smaller, but V. tricorpus produced large microsclerotia, even when they were absent in pure culture. Morphological characteristics suitable for discrimination between the two species on MSEA plates in the presence of soil were selected and tested with fresh isolates from agricultural fields. The two fungi could be distinguished using qualitative characteristics and microsclerotial size. Molecular analysis and morphology on potato dextrose agar confirmed all identifications made on soil dilution plates.

Aflatoxins (AFs) are secondary metabolites produced mainly by Aspergillus parasiticus and A. flavus. To study AF regulation, previously isolated non-toxigenic A. parasiticus sec− (for secondary metabolism minus) variants were genetically analysed. In parasexual crossing, the sec− strains failed to form heterokaryons and diploids with other sec− strains. Heterokaryon test results suggested that involvement of cytoplasmic elements in the formation of sec− phenotype was unlikely. At the molecular level, the coding sequence of the sec− aflR (the only known positive regulator of AF pathway) was identical to that of their toxigenic sec+ (for secondary metabolism plus) parents. However, the sec− aflR expression was 5- to 10-fold lower compared to that in the sec+ forms. RT–PCR analysis demonstrated that the AF pathway genes were expressed in the sec− forms but in trace amounts and in their unprocessed forms. Combined, these results suggest that aflR is necessary but not sufficient for AF production and that elements involved in fungal development directly or indirectly influence its proper function.

A genomic clone of the aflatoxin-producing fungus Aspergillus flavus, designated pAF28, has been used as a probe for Southern blot fingerprinting of fungal strains. A large number of A. flavus strains isolated from corn fields and tree-nut orchards can be distinguished because the DNA fingerprint patterns are highly polymorphic. We have completed the sequencing of a 6355 bp insert in pAF28. The sequence features motifs and open reading frames characteristic of transposable elements of the gypsy class. We have named this new element AfRTL-1, for A. flavusretrotransposon-like DNA.

Helicobasidium mompa is a clampless basidiomycete and binucleate both in secondary and primary hyphae. Single basidiospore isolates were paired in sibling and non-sibling combinations. We did not observe any alterations in colony morphology, such as tuft formation, but mycelial incompatibility, as indicated by the presence of a dark demarcation line between colonies, occurred in a unifactorial manner. Techniques using DNA molecular markers, such as internal transcribed spacer-restriction fragment-length polymorphism (ITS-RFLP), inter–simple-sequence-repeat polymerase chain reaction (PCR), and universally primed PCR, failed to identify nuclear migration to opposite single basidiospore isolates in all but one of the 92 pairings. These results imply that single basidiospore isolates of H. mompa may be incompetent to mate under laboratory conditions and that a single mycelial incompatibility factor operates in single basidiospore isolates.

Colletotrichum lagenarium is a plant pathogenic fungus, and produces melanin that is an essential factor for appressorial penetration into host tissues. The melanin biosynthesis pathway of C. lagenarium starts with pentaketide synthesis catalyzed by polyketide synthase Pks1p. We previously confirmed that the direct product of Pks1p is 1,3,6,8-tetrahydroxynaphthalene. Thus, melanin biosynthesis in this fungus requires the reduction of 1,3,6,8-tetrahydroxynaphthalene to scytalone. We made a double mutant 9141-144 from the thr1 mutant 9141 that lacks the ability to metabolize 1,3,8-trihydroxynaphthalene. The double mutant 9141-144 could metabolize neither 1,3,6,8-tetrahydroxynaphthalene nor 1,3,8-trihydroxynaphthalene. However melanin production by the double mutant was restored by THR1, indicating that Thr1p can metabolize both compounds in vivo. These results demonstrate that two enzymes, Thr1p and a deduced 1,3,6,8-tetrahydroxynaphthalene-specific reductase, are involved in the first reduction step of the melanin biosynthesis pathway of C. lagenarium.

Metal-contaminated soils often contain a spatially heterogeneous distribution of metal concentrations, and the ability of fungi to colonize such metal-contaminated domains will be influenced by the nutritional resources available. An experimental system based upon tessellated agar tiles was used to study the influence of nutrients upon the ability of soil fungi Trichoderma virens and Clonostachys rosea to colonize spatially discrete toxic metal (copper and cadmium) containing domains. The growth parameters recorded demonstrated a decrease in apparent metal toxicity with increasing concentration of available carbon source. It was shown that maximum hyphal extension rates and the efficacy of carbon substrate utilization of both species decreased with increasing concentration of toxic metals. It was also observed that in the gap between metal-free and metal-containing tiles, the presence of toxic metals led to negative chemotropic reactions and cessation of growth, swelling and lysis of some hyphal tips. Penetration of the hyphae into the metal-containing domain was often followed by the formation of very dense mycelia or mycelial ‘bushes’ representing an associative (constraining, exploitative or ‘phalanx’) growth strategy of the mycelial system. After the fungi entered the toxic metal-containing domains, they often produced long sparsely-branched or branchless explorative hyphae representing a dissociative (expansive, explorative or ‘guerrilla’) growth strategy. Our data therefore demonstrate that fungi efficiently use both ‘phalanx’ and ‘guerrilla’ states of the mycelial system as well as shifts in these growth strategies as a response to toxic metal stress combined with nutritionally-poor conditions.

Entomophthorales pathogenic to insects and mites often cause epizootics in their host populations, but some have been difficult to culture in vitro and, therefore, to develop as biopesticides. Grace's insect cell culture medium supplemented with lactalbumin hydrolysate and yeastolate has allowed growth of several species which until recently were referred to as obligate parasites. The research reported here was designed to evaluate the effects of the salts, vitamins and amino acids used to prepare the insect cell culture medium on in vitro growth of Batkoa sp. and Furia sp., pathogens of the spittlebug pests of pasture and sugar-cane in Brazil, and Neozygites floridana, a pathogen of several mite species. Also, several sources of carbon and nitrogen were examined. Batkoa sp., Furia sp. and N. floridana were similar concerning their growth patterns in a basic medium with added salts, vitamins and amino acids, as well as with a combination of all three compoments. The addition of salts to the basic medium of sugars plus lactalbumen hydrolysate and yeastolate caused a significant increase in biomass production of the three fungal species. The addition of vitamins and amino acids had less effect. Batkoa sp., Furia sp. and N. floridana are similar in growth patterns in media with various sources of carbon, but different in media with different sources of nitrogen. The production of the three fungal species is significantly higher in medium containing 2.66% glucose than in medium with 2.66% sucrose. The addition of 0.1% monossacarides to media containing 2.66% sucrose did not significantly increase biomass production.

Field surveys were carried out in coffee plantations in Chiapas, Mexico, to collect and identify fungi associated with the cuticle, gut, faeces and galleries of the coffee berry borer, Hypothenemus hampei. Insects and coffee berries containing galleries were collected in three coffee farms at different altitudes: Rosario Izapa (425 m), La Alianza (700 m) and Monteperla (950 m). An additional sample consisting of coffee berry borers reared in the laboratory on meridic diets was also included. Results show that there is a great diversity of fungi associated with this insect. 212 cultures, including 40 species distributed in 22 genera, were isolated. The recovery of fungi from the galleries was markedly less than from the borer's body. Three of the isolated species were undescribed; two belonging to the Penicillium and one to Hanseniaspora. Most of the species were collected from the cuticle of the insect, and the presence of fungi was not correlated with altitude. Fusarium, Penicillium, Candida and Aspergillus were the dominant genera with percentage abundance of 26.4, 18.7, 13.4 and 12.5%, respectively. The present study provides a detailed description of the mycobiota associated with H. hampei and represents a significant advance in the understanding of the relationship among this insect and the fungi associated with it.

During an investigation of mycoparasitic fungi on sclerotia of Sclerotinia sclerotiorum in China, a new fungal species was consistently encountered and isolated from natural soils taken from soybean fields of Shandong and Jiangsu Provinces. The fungus is featured by its sphaeroid conidia with 1–2 transverse septa, but mostly (>65%) with only one septum at the base. It resembles Monacrosporium indicum, M. sphaeroides and M. sinense, but can be distinguished from the first two species by lack of basal hila and large vacuoles on its conidia, respectively, and from M. sinense by its typically two-celled and broadly turbinate to napiform conidia. Colonization frequencies on S. sclerotiorum sclerotia by the new species were 10% and 33.3% in the two field soils, respectively, when the sclerotia were introduced into soils and coincubated at 22–24 °C for 4 wk. Reinoculation tests by placing surface-sterilized sclerotia onto the tested isolate colony for 2 wk and then surface-sterilized again resulted in 23.3% sclerotia colonized. Microscopic observations indicated that the fungus coiled around hyphae of Rhizoctonia solani and grew along and appressed to hyphae of Fusarium solani f.sp. pisi, S. sclerotiorum and Phytophthora cactorum when dual-cultured in slides. Tests on agar plates demonstrated that the fungus formed adhesive networks and was an active predator of Panagrellus redivivus. This study indicated the diverse mechanisms for the fungus to survive in soil. For expression of its mycoparasitic and nematode-trapping capacities, the fungus is named as Monacrosporium janus.