This issue of Mycological Research News features: How safe is Aspergillus niger?; Advantage, invasive plants; and Forthcoming international mycological meetings.

Sixteen original papers are included in this part. Those with a molecular or phylogenetic thrust address the polyphyletic nature of Paraphaeosphaeria, report the discovery of a teleomorph for Marchandiomyces, address the separation of Neofabraea spp., variation in Pythium insidiosum, the separation of cereal rusts, reveal a new Diplodia within Sphaeropsis sapinea auct., and demonstrate host-linked genotypes within Corynespora cassiicola. Telomere fingerprinting in Beauveria bassiana is reported, Hypocrella (incl. Aschersonia) spp. are shown to be cytotoxic to insect cells, and the efficacy of natural mycoparasites aginst cocoa diseases is demonstrated.

The separation of South American Polyporus spp. by isoenzymes, and of Agaricus spp. by volatiles using an electronic nose, is described. Alginate beads can be used to preserve arbuscular mycorrhizal fungi long-term, the basis of reduced aflatoxin production in Aspergillus flavus mixed cultures is deduced, and the importance of oxidative stress in sclerotial formation in Sclerotinia demonstrated. The results of an extensive seven-year study of macromycetes in Austria with implications for recording practices are also presented.

The following new scientific names are introduced: Marchandiobasidium, Neophaeosphaeria, and Phaeosphaeriopsis gens. nov.; Diplodia scrobiculata, M. aurantiacum, and P. amblyspora spp. nov.; N. barrii (syn. Paraphaeosphaeria barrii), N. conglomerata (syn. P. conglomerata), N. filamentosa (syn. Leptosphaeria filamentosa), N. quadriseptata (syn. P. quadriseptata), Phaeosphaeriopsis agavensis (syn. Paraphaeosphaeria agavensis), Phaeosphaeriopsis glauco-punctata (syn. Cryptosphaeria glauco-punctata), P. obtusispora (syn. L. obtusispora), and P. nolinae (syn. Paraphaeosphaeria nolinae) combs. nov.

Two new genera, Neophaeosphaeria and Phaeosphaeriopsis, are described to accommodate species of Paraphaeosphaeria that are not congeneric based on morphological characters and results of 18S rDNA sequence analyses. Paraphaeosphaeria s. str. is restricted to species with two-septate ascospores and anamorphs that produce non-septate, smooth, pale brown conidia enteroblastically from phialides which have some periclinal thickening. Species in Neophaeosphaeria have 3–4-septate ascospores and anamorphs that produce ovoid to ellipsoid, non-septate, brown, verrucose or punctate conidia from percurrently proliferating conidiogenous cells. Paraphaeosphaeria barrii, P. conglomerata, P. filamentosa and P. quadriseptata are transferred to Neophaeosphaeria. At present all species in Neophaeosphaeria occur on Yucca (Agavaceae). Phaeosphaeriopsis is described for species that produce 4–5-septate ascospores. Known anamorphs produce cylindrical, 0–3-septate, brown, punctate conidia from percurrently proliferating conidiogenous cells or bacillar conidia from simple phialides. P. agavensis, P. glauco-punctata, P. nolinae and P. obtusispora are transferred to Phaeosphaeriopsis. P. amblyspora is described as a new species.

The name Marchandiobasidium aurantiacum gen. sp. nov. is introduced for the teleomorph of Marchandiomyces aurantiacus. Dolipore septa and septal pore caps of the closely related Marchandiomyces corallinus are typical of the Ceratobasidiales, and the basidiomatal characters of Marchandiobasidium aurantiacum are reminiscent of those of the monotypic genus Waitea. Morphological, ultrastructural and molecular data suggest that Marchandiobasidium should not be included in Waitea, but should be treated as a distinct genus.

Five species of pathogenic fungi belong to Neofabraea. One of these, N. krawtzewii (syn. N. populi), is responsible for bark lesions on poplar (Populus) trees. The other four species cause post-harvest bull's eye rot of pome fruits, and at least two of these also cause bark cankers on pome fruit trees. Morphological variation among these species is slight, and overlap in geographic range sometimes occurs. As a consequence, identification based on conventional criteria can be tenuous. PCR primers with putative species specificity were developed following genetic analysis of the β-tubulin gene for isolates of each of the five species of Neofabraea. PCR conditions required to achieve specificity of the primer sets were determined, and a multiplex PCR protocol was developed to optimize their diagnostic utility on apple fruits. A protocol with higher annealing temperatures in the initial PCR cycles followed by lower temperatures in later cycles gave complete species-specificity when the primer sets were used individually and in multiplex, resulting in successful detection of the pathogens from axenic culture and infected apple fruits.

Sequence analysis of the ribosomal DNA internal transcribed spacers (ITS) was used to establish phylogenetic relationships among 23 isolates of Pythium insidiosum, the etiological agent of pythiosis in mammals. The isolates were divided into three distinct clades that exhibited significant geographic isolation. Clade I consisted of isolates from North, Central, and South America, while clade II contained isolates from Asia and Australia. Also present in clade II was an isolate from a patient in the USA, but the origin of the infection may have been in the Middle East. Clade III was comprised of isolates from Thailand and the USA. All 23 P. insidiosum isolates were more closely related to each other than to any other Pythium species in this study. Additionally, all Pythium isolates formed a clade separate from both outgroup species, Phytophthora megasperma and Lagenidium giganteum. The ITS sequence results tend to support the existence of geographic variants or cryptic speciation within P. insidiosum. The sequence information obtained also provides an abundance of data for applications in the diagnosis of pythiosis and identification of P. insidiosum from clinical samples.

Rust fungi cause economically important diseases of cereals, and their ability to rapidly evolve new virulent races has hindered attempts to control them by genetic resistance. PCR-based molecular tools may assist in understanding the genetic structure of pathogen populations. The high multiplex DNA fingerprinting techniques, amplified fragment length polymorphisms (AFLP), selectively amplified microsatellites (SAM) and sequence-specific amplification polymorphisms (S-SAP) were assessed for their potential in investigations of the genetic relationships among isolates of the wheat rust pathogens, Puccinia graminis f. sp. tritici (Pgt), Puccinia triticina (Pt), and P. striiformis f. sp. tritici (Pst), the oat stem rust pathogen P. graminis f. sp. avenae (Pga), and a putative new P. striiformis special form tentatively designated Barley grass yellow rust (Bgyr). Marker information content, as indicated by the number of species-specific fragments, polymorphic fragments among pathotypes, percentage of polymorphic loci, and the marker index, was highest for the SAM assay, followed by the AFLP and S-SAP assays. UPGMA analysis revealed that all marker types efficiently discriminated the five different taxa and Mantel tests revealed significant correlations between the marker types. Within pathogen groups, the marker types differed in the amount of variation detected among isolates; however, the major differences were consistent and polymorphism was generally low. This was reflected by the AMOVA analysis that significantly partitioned 90% of the genetic variation between taxa. Of the three marker types, SAMS were the most informative, and have the potential for the development of locus-specific microsatellites.

Sphaeropsis sapinea is an opportunistic pathogen causing serious damage to conifers, pre-disposed by adverse environmental conditions or mechanical damage. Three different morphological forms of the fungus have been described and are commonly referred to as the A, B and C morphotypes. Isolates of the different morphotypes have also been separated based on differences in pathogenicity and molecular characteristics. These differences, however, overlap and have not been considered sufficiently robust to justify the description of separate taxa. The aim of this study was to consider relationships between isolates representing different S. sapinea morphotypes, using multiple gene genealogies inferred from partial sequences of six protein-coding genes and six microsatellite loci. Genealogies generated for the protein-coding genes and microsatellite loci were not congruent but both consistently grouped isolates representing the A and C morphotypes in separate but closely related clades. In contrast, isolates of the B morphotype grouped together in a clade that was equally different to the A and C morphotypes as it was to the clade encompassing isolates of Botryosphaeria obtusa. These results provide strong evidence to show that the B morphotype isolates are distantly related to S. sapinea and represent a discrete taxon, which we describe here as Diplodia scrobiculata sp. nov.

Genetic variation of 42 isolates of Corynespora cassiicola, a destructive fungal pathogen of many economically important crop plants including rubber, was investigated using RAPD–PCR analysis. Five genetic groups were identified using RAPD–PCR profiles generated by eight random primers. Results indicate that there is a significant genetic variation among C. cassiicola isolates collected from different host plants. These results should facilitate the development of rubber clones with enhanced resistance against all genetic groups of C. cassiicola.

Beauveria bassiana is a popular biocontrol agent used as ‘green’ pesticide in crop insect pest management. Chromosome number has been variously reported as five, six, seven and eight in this species. The range of chromosome number and the minimum chromosome number in this economically important fungus were assessed through telomere fingerprint analysis of a sample of 17 isolates from different and similar hosts and distant and same geographic origin. Genomic DNA digested with EcoRI, which has no cutting site in the telomere repeat sequence arrays was probed with a radioisotope-labelled (5′-TTAGGG-3′)8 oligonucleotide. The probe-hybridised regions appeared as discrete bands – each representing a telomere. The number of bands in each lane was counted and halved to arrive at the chromosome number of that isolate. The chromosome number varied from 5 to 10 in the different isolates. The telomere probe hybridised bands were also scored for presence or absence in a 0–1 matrix and a dendrogram based on similarities between the isolates was constructed using the NTSYS-pc ver. 2.02i software. The isolates showed very little similarity; the overall similarity was 14%. Only two isolates which were of diverse host and geographic origin showed 100% similarity. Isolates from the same epizootic that showed 43% similarity in their telomere fingerprints had 96% similarity in their RAPD (Random amplified polymorphic DNA) fingerprints with 10 primers. The genetic distances computed from any one DNA fingerprinting method thus do not reflect the true genetic similarities of the isolates. The frequency distribution pattern of the pair-wise similarities computed from telomere fingerprints hinted at the occurrence of recombination in this fungus. Telomere fingerprinting proved very useful in typing isolates since each of them was found to have a unique fingerprint. Isolates with the same chromosome number neither showed a distinct morphology or virulence character nor a close similarity in telomere or RAPD fingerprints to merit their subgrouping into a taxonomically relevant or practically useful unit.

Extracts from entomopathogenic fungi of the genus Hypocrella (7 species) and its anamorph Aschersonia (11 species) were screened for cytotoxicity to Sf9 and C6/36 insect cells and L929, BHK(21)C13 and HepG2 mammalian cells. Cytotoxic extracts to insect cells (ID50's[les ]10 μg ml−1) but not to mammalian cells (ID50's[ges ]10 μg ml−1) conformed to the criteria of the project and were considered ‘lead’ extracts for further investigation. ‘Leads’ were found in two of the Hypocrella species: H. discoidea, and H. tamurai and in three of the Aschersonia species: A. samoensis, A. badia, and A. tamurai. Bioassay-guided fractionation of the cell extract of the fungus A. samoensis BCC 1393 led to the identification of two known anthraquinone dimers, (+)rugulosin (1) and skyrin (2) which showed selective toxicity towards insect cells. (+)Rugulosin (1) and skyrin (2) exhibited strong cytotoxic activity against the insect cell line Sf9 with respective ID50 values of 1.2 and 9.6 μg ml−1, but showed weak activity toward mammalian cells. This first report of (+)rugulosin (1) and skyrin (2) in A. samoensis is confirmed and demonstrated in another four strains of A. samoensis isolated in Thailand. The preferential cytotoxicity against Sf9 insect cells gives evidence that these insect-pathogenic fungi of the Hypocrella/Aschersonia group might be useful as an agent for pest control.

Mycoparasites collected from aerial parts of the cocoa plant (Theobroma cacao) have shown great promise in the control of black pod, caused by Phytophthora palmivora, and moniliasis, caused by Moniliophthora roreri. However, the ecology of epiphytic mycoparasites is still poorly understood although it has a direct bearing on applied biocontrol practices, ranging from the identification and isolation of promising biocontrol candidates to formulation needs and required application frequency. One objective of this study was to determine the natural abundance of mycoparasites on cocoa flowers and pods in relation to crop development stage and cultivar. For this purpose, native mycoparasites were detected on cocoa flowers and pods using the precolonised plate baiting technique. Furthermore, the survival of an applied Clonostachys rosea isolate on cocoa pods on shaded and non-shaded trees was compared as well as the recolonisation patterns of surface-sterilised pods by native mycoparasites under these conditions. Clonostachys spp. were the most commonly isolated native mycoparasites, followed by Fusarium spp. No differences in the occurrence of native, epiphytic mycoparasites were observed between the three main cocoa cultivars, ‘Criollo’, ‘Forastero’ and ‘Trinitario’, nor between clones within these groups. Thus, a single biocontrol inoculum can be suitable for application to cultivar mixtures of cocoa commonly grown together in a field. Different susceptibility classes of segregating F1 populations of hybrids with resistance against M. roreri and P. palmivora supported similar population levels and taxonomic assemblages of mycoparasites. Therefore, we reject the hypothesis that these antagonists mediate resistance. Mycoparasite abundance and genetic disease resistance to black pod and moniliasis are independent phenomena and should lead to additive effects if employed simultaneously in an integrated disease management programme. The survival of applied C. rosea was not affected by the shading regime or any other meteorological parameter measured. On the other hand, recolonisation of surface-sterilised cocoa pods by most native mycoparasites was faster in the shade. Only Trichoderma spp. colonised pods exposed to direct sunlight faster than shaded ones. The implications for the design of biocontrol inocula and formulation technology are discussed.

Forty-two dikaryotic and 42 monokaryotic isolates, and 34 pairings were examined by horizontal polyacrylamide gel electrophoresis (PAGE) for six enzymatic activities, viz. EST, 6PGD, IDH, MDH, SHDH and SOD. 44 bands were analysed. Numerical analysis of the isoenzymatic patterns was undertaken and compared with those from morphological characters. The analysis of six enzymatic systems showed the existence of four monomorphic systems (IDH, MDH, SHDH and SOD). The sterease system (EST) appears to be polymorphic in Polyporus ciliatus and in populations of P. tenuiculus from Argentina, being monomorphic in the remaining species studied. The 6PGD system is polymorphic in P. tucumanensis and monomorphic in the other species. Predominance of monomorphic enzymes and a clear distribution of the electromorphs among the species, indicates that isoenzymatic analysis is a good taxonomic tool within Polyporus. The low intraspecific variability allowed the use of interspecific differences to separate species. Numerical analysis showed a good correlation between morphological and molecular characters. In the isoenzymatic phenogram the similarity index is high only among very close species, showing a stressed separation of species.

Comparisons of the qualitative volatile production patterns between seven species of Agaricus, and between two of Volvariella and Pleurotus and one Coprinus species when grown at 25 °C on agar media for 14 d were made. There was good reproducibility between the volatile production patterns of the same species using an electronic nose unit with a 14 conducting sensor polymer array. Principle Component Analysis (PCA) showed that it was possible to discriminate between five of the seven Agaricus species, but that some overlap occurred between the others. Cluster analysis showed that there was also overlap between some species with the tropical collection of A. bitorquis separating out from the others. The volatile production profile of the commercial A. bisporus was close to that of a wild species, A. campestris. A. bisporus could be readily differentiated from other non-Agaricus species. This study demonstrates the potential for using electronic nose systems to rapidly differentiate mycelial cultures of homobasidiomycete mushrooms.

Intraradical vesicles of Glomus intraradices were isolated, entrapped in alginate beads, and stored at 4 °C for periods from 2–74 months. The beads were used to inoculate leeks grown under standard conditions for 6 wk, then development of root colonization by G. intraradices was recorded. Colonization of leeks was high (mean >50% in length) and did not vary markedly until five years of storage. After six years of storage, the inoculum proved infective and viable.

The ability of two non-aflatoxin producing strains of Aspergillus flavus to interfere with aflatoxin production by a toxigenic A. flavus strain was examined using a replacement series with suspended disc culture method. Individual glass fiber discs, affixed to a pin suspended from the caps of scintillation vials, were inoculated with medium containing A. flavus conidial mixtures in different proportions (aflatoxin producer[ratio ]non-producer=100[ratio ]0, 80[ratio ]20, 60[ratio ]40, 20[ratio ]80 and 0[ratio ]100 by vol) at a constant total density (1×105 spores ml−1). Reductions in the total conidial density of these strains when grown alone, had little effect on fungal growth (mycelium dry weight) or aflatoxin production. Significant (P<0.0001) reductions in aflatoxin B1 were recorded when non-toxigenic strains represented any proportion of the inoculum mixture. Aflatoxin yield values were less than (P<0.0001) expected from the input ratios for toxigenic vs. non-toxigenic conidial inoculum within the replacement series. Aflatoxin yields were also reduced (P<0.001), with a corresponding increase in fungal growth (P<0.001), when conidia from aflatoxin producing strains were mixed in equal proportions. This suggests that the substantial inhibition of aflatoxin yield for inoculum mixtures results from the failure of spore germlings to establish a cooperative mycelial network.

Sclerotinia minor accumulates β-carotene at levels dependent upon oxidative growth conditions and differentiation. β-carotene accumulation is 2.5-fold higher in differentiated mycelia at high than at low oxidative stress, and approx. 3-fold higher in differentiated than in undifferentiated mycelia. It is proposed that β-carotene may be produced by the fungus to counteract oxidative stress that develops during growth. This is shown by the finding that exogenous β-carotene at growth non-inhibiting concentrations causes a concentration-dependent reduction of oxidative stress (lipid and protein peroxidation) and sclerotial differentiation in this fungus. The data of this study support our hypothesis that sclerotial differentiation in phytopathogenic fungi may be induced by oxidative stress.

Almost 900 species were encountered during a seven year survey of fungal fruit bodies in 13 forests and grasslands plots measuring about 1 ha. The data were comparable to those from a Swiss forest plot monitored for 21 years. Species richness and abundance were almost linearly correlated on a log/log scale. Abundance and yearly frequency of species were tightly correlated. The geographic range of species may also be related to these two parameters. Rare species scored low on abundance, yearly frequency and geographic range. About half of the species were rare, and occurred in only one out of seven years. The two major functional groups of saprotrophic and mycorrhizal species behaved similarly over the years, as in the Swiss study.

Annual variation was high for species richness alone and for richness combined with abundances. The log transformed species richness of plots correlated well with parameters that take the abundances or yearly frequencies of species into account. If other mushroom assemblages show similar regularities, it may be possible to omit abundance counts in future surveys. The species composition of the plots varied strongly over the years. Many species did not reach their maximum abundance in the richest year. Species showed their maximum abundances in different plots in the same year more often than expected by chance. Thus the presence and abundance of species depended on factor(s) other than the general productivity of a year, and years showed (a) different aspect(s) than productivity alone. Long-term surveys are important for understanding the structure of mushroom assemblages and their biodiversity.