Mycological Research News features: Nitrogen deposition and mycorrhizal community structure; and Identity the causal agent of rice blast.

This issue includes two review articles: an appraisal of endophytic fungi as a source of biologically active metabolites; and PCR-based methods for the detection and quantification of mycotoxin-producing fungi. Effects of antioxidants on toxin and enzyme production in Fusarium verticilloides and F. proliferatum have been investigated, as has the accumulation of toxins produced by the last species in maize.

Molecular phylogenetic papers describe a new order of ascomycetes for the aquatic genus Jahnula and its allies, assess relationships in the lyophyllid agarics, and provide new data supporting the isolation of the plasmodiophorids. Also reported are molecular studies on variability in Paecilomyces fumosoroseus, chromosome-length polymorphisms in Botryotinia fuckeliana (anam. Botrtyis cinera), the occurrence of the snowberry pathogen Erysiphe symphoricarpi in Europe, anamorph-teleomorph connections in Cordyceps, and four new Penicillium species with dark pigmented conidiophores.

The following new scientific names are introduced: Jahnulales ord. nov.; Patescospora gen. nov.; Jahnula siamensiae, P. separans, Penicillium boreae, P. canarinse, P. pullum, and P. subarcticum spp. nov.; and J. sunyatsenii (syn. Aliquandostipite sunyatsenii) comb. nov.

In the continual search by both pharmaceutical and agricultural industries for new products, natural selection has been found to be superior to combinatorial chemistry for discovering novel substances that have the potential to be developed into new industrial products. Since natural products are adapted to a specific function in nature, the search for novel secondary metabolites should concentrate on organisms that inhabit novel biotopes. Endophytic fungi inhabit such a biotope. In the course of the last 12 years, we have isolated ∼ 6500 endophytic fungi from herbaceous plants and trees, screened them for biological activities, and have isolated and determined the structures of the biologically active compounds. Correlations were found between biological activity and biotope, e.g. a higher proportion of the fungal endophytes, in contrast to the soil isolates, inhibited at least one of the test organisms for antialgal and herbicidal activities. The substances isolated originated from different biosynthetic pathways: isoprenoid, polyketide, amino acid derivatives, and belonged to diverse structural groups: terpenoids, steroids, xanthones, chinones, phenols, isocumarines, benzopyranones, tetralones, cytochalasines, and enniatines. The potential role of the endophyte and its biologically active metabolites in its association with its host has been investigated. The fungal endophytes possess the exoenzymes necessary to colonize their hosts and they grow well in the apoplastic washing fluid of the host. When the roots of larch are colonized, the association with the host may be mutualistic, improving growth of the host and supplying the mycobiont with enough nourishment to extensively colonize the host's roots. The concentrations of some plant defence metabolites are lower than in the control when the host is infected with a pathogen than with an endophyte. We hypothesize that the interaction fungal endophyte–plant host is characterized by a finely tuned equilibrium between fungal virulence and plant defence. If this balance is disturbed by either a decrease in plant defence or an increase in fungal virulence, disease develops. Not only must the endophyte synthesize metabolites to compete first with epiphytes and then with pathogens in order to colonize the host, but presumably also to regulate metabolism of the host in their delicately balanced association. The utilization of a biotope such as that of the fungal endophyte is one aspect of intelligent screening, another very important one is the taxonomy of the fungus in order to avoid redundant structural isolations. It is not a random walk through a random forest. Many groups of fungi in different biotopes are waiting to be exploited.

Mycotoxins are secondary metabolites produced by many phytopathogenic and food spoilage fungi including Penicillium, Fusarium and Aspergillus. The toxicity and carcinogenicity of many of these mycotoxins, and their potential to contaminate foods and animal feedstuffs is a cause of serious concern globally, both from a food safety and food trade standpoint. Thus the rapid identification of mycotoxigenic fungi would be desirable, such that early intervention steps could be applied to help limit the amounts of contaminated materials, particularly cereals and cereal-based products, gaining access to the human food chain. With this in mind a number of PCR-based methodologies have been developed for the identification of mycotoxin biosynthetic genes in different fungal genera, together with assays developed using other genes or random amplification of polymorphic DNA (RAPD) methodologies for the identification of specific toxigenic fungi. In addition, reverse transcription (RT)-PCR, competitive PCR and Real Time quantitative PCR methodologies have also been developed for this purpose. The development of each of these techniques, their usefulness, limitations and adaptability will be discussed together with descriptions of specific examples where these techniques have been utilised in different experimental settings.

The ear rot severity of 15 maize hybrids and the accumulation of fumonisin B1 (FB1), fumonisin B2 (FB2), beauvericin (BEA) and fusaproliferin (FP) after artificial inoculation in the field with a toxigenic strain of Fusarium proliferatum has been investigated in Poland during the seasons 1996, 1997 and 1999. The year of inoculation proved a significant influence on ear infection degree and mycotoxin accumulation. Inoculated ears contained 11–71% Fusarium-damaged kernels. Mycotoxins were detected in all hybrids at levels of 18–231.9 μg g−1 for FB1, 0.4–26.5 μg g−1 for FB2, 0.2–19.6 μg g−1 for BEA and 0.3–6.4 μg g−1 for FP. Mycotoxin concentrations were higher in Fusarium-damaged kernels (up to 361.5, 41.1, 44.3 and 10.0 μg g−1 for FB1, FB2, BEA and FP, respectively) than in healthy-looking kernels (up to 26.0, 2.3, 1.9, 0.3 μg g−1 for FB1, FB2, BEA and FP, respectively). All hybrids showed high susceptibility to the fungal infection and high toxin content in kernels during the three years of investigation.

A new order is introduced (Jahnulales) to accommodate ascomycetes with stalked/sessile and dimorphic ascomata, hyphal stalk cells that are ca 40 μm wide, and ascospores that are unequally 2-celled with or without various types of appendages or sheaths. The order includes a single family, the Aliquandostipitaceae, and has affinities with the Pleosporales within the Dothideomycetes. Studies on freshwater ascomycetes in Egypt and Thailand yielded one new genus Patescospora, and Jahnula siamensiae sp. nov., and the new combination J. sunyatsenii (syn. Aliquandostipite sunyatsenii) is made based on molecular results.

Current classifications of the Lyophylleae and the importance of siderophilous granulation in the basidia for the classification of agaricoid fungi were evaluated using parsimony analyses of sequence data from the nuclear ribosomal large subunit gene (nLSU), the internal transcribed spacer region of the nuclear ribosomal array (ITS), and the mitochondrial ribosomal small subunit gene (mtSSU). These three different data partitions were phylogenetically congruent on the basis of the Mickevich–Farris statistical test, but not from the ILD and the Templeton tests. Bootstrap supports for nodes in phylogenetic trees generated from combined nLSU, ITS, and mtSSU sequence data were generally higher than those in trees generated from individual data sets. This suggests a lack of major conflict in the phylogenetic signal among the different data sets. We conclude that the Mickevich–Farris test is more appropriate for estimating congruence and combinability between different sources of molecular data than the more widely used ILD and Templeton tests, at least when the different data sets have their respective resolution power at different depths in the phylogeny. Results of the combined analyses show that the Entolomataceae are a sister group to a clade composed of the Lyophylleae, Termitomyceteae, and Tricholomateae p.p. This implies that presence of siderophilous granulation in the basidia of agaric fungi has probably a single origin, and would have been lost in the Tricholomateae. Inclusion of the Termitomyceteae within the Lyophylleae suggests homology of the macro type granulation. Because the exact placement of Tricholomateae pro parte remains uncertain, it remains unclear whether the Lyophylleae (including Termitomyceteae) are monophyletic or paraphyletic. Within the Lyophylleae, genera Lyophyllum and Calocybe are shown to be artificial, as are Lyophyllum sections Lyophyllum, Difformia, and Tephrophana. Four main natural groups of Lyophylleae have been identified that should serve as a basis for developing a more natural classification system for these fungi.

Spongospora nasturtii is a plasmodiophorid pathogen of watercress (Rorippa nasturtium-aquaticum), causing crook root disease. In the past, some authors have considered the plasmodiophorids as protists, and others have considered them as true fungi. This study was performed with the aims of elucidating both the relationship of S. nasturtii to other plasmodiophorids, and also the placement of the plasmodiophorids as a group when compared to other organisms. Analysis of partial 18S ribosomal DNA sequences of a range of plasmodiophorids by phylogenetic techniques including parsimony, neighbour-joining, and principal co-ordinate analysis, indicated that there was a close relationship between S. nasturtii, S. subterranea and Plasmodiophora brassicae. However, analyses incorporating 1.2 kb of 18S rDNA sequence from S. subterranea cast doubt over the long-held view that S. subterranea and S. nasturtii are more closely related to each other than to other genera of plasmodiophorids. Consideration of the entire 18S rDNA of both S. nasturtii and P. brassicae showed that they are not closely related to a range of protists and true fungi examined.

The entomopathogenic hyphomycete Paecilomyces fumosoroseus is a promising candidate for biocontrol of economically important agricultural pests. Assessment of genetic relatedness of this species appears to be essential to gain insight into the monitoring of such biocontrol products. Intraspecific variation within the internal transcribed spacer region of the ribosomal RNA gene (rDNA-ITS) was studied in 48 isolates of P. fumosoroseus. These strains were isolated from different geographical and biological origins, more particularly from the silverleaf whitefly, Bemisia tabaci-argentifolii (Homoptera: Aleyrodidae), a major insect pest in field and greenhouse crops. PCR amplification of the ITS1-5.8S-ITS2 rDNA region followed by restriction analysis of the PCR products underlined the overall highly variable nature of this region. Digestion with the six endonucleases AluI, HaeIII, Hin6I, HpaII, NdeII, and SmaI allowed the separation of the isolates into three distinct groups. The group 1, representing 25 isolates, is composed of strains isolated only from the host B. tabaci-argentifolii. By contrast, the group 3 is more diffuse as it included strains from various insect host and geographical origins. Phylogenetic analysis of rDNA-ITS sequence data strongly supported the conclusions of the PCR-RFLP analysis and recognized three monophyletic groups within the P. fumosoroseus complex. The high level of polymorphism within the P. fumosoroseus species is discussed in the light of their biological origin.

The electrophoretic karyotype (EK) of 24 strains of Botryotinia fuckeliana was resolved to determine the extent of chromosomal polymorphism among them. Based on EK variation, nine different profiles with a number of bands ranging from 5 to 8 were found. Those profiles were not related to the origins of the strains, hosts, or year of isolation. Inheritance of chromosomal bands was studied by analyzing the EK of the progeny from crosses between sexually compatible B. fuckeliana strains that had different karyotype. The EKs of 44 monoascospore strains showed 12 new EK profiles, suggesting that chromosomal rearrangements generated after meiotic recombination provides EK variability in this fungus. Also, we report here that the degree of EK variability indicates that sexual reproduction under natural conditions might be quite important in the life cycle of B. fuckeliana. Hybridization analysis showed that, in most strains, the rDNA is located in both a chromosomal band of high molecular weight and different size depending on the strain and a band of low molecular weight, revealing evidence for chromosome rearrangements in this plant pathogen.

Recently, a powdery mildew anamorph infecting snowberry (Symphoricarpos albus) has been reported as a new plant pathogen in several European countries. We report here its occurrence in the UK, Germany and, for the first time, Switzerland. Based on morphological and scanning electron microscope (SEM) patterns, this novel pathogen appeared similar to the anamorph of a common North American powdery mildew, Erysiphe symphoricarpi (syn. Microsphaera symphoricarpi). A phylogenetic analysis of the internal transcribed spacer (ITS) sequences of the ribosomal DNA (rDNA) of an English and a North American snowberry powdery mildew fungus showed that they are conspecific. Ascomata of the pathogen were found only in one European collection, that being in Germany in 2002. The similarity in morphology of the ascomata also confirmed the co-identity of the European and American snowberry powdery mildews.

The effect of single or mixtures of antioxidants on the lag phase prior to growth, growth rate, hydrolytic enzyme production (N-acetyl-β-glucosaminidase, β-D-glucosidase and α-D-galactosidase) and fumonisin production by Fusarium verticillioides and F. proliferatum was evaluated on maize-based media at 25 °C, and under different water activity (aW) conditions. An increase in the lag phase (h) was observed for both F. verticillioides and F. proliferatum especially with propyl paraben (PP)+butylated hydroxyanisole (BHA) treatments at all aW levels tested. For both species PP alone or in combination with BHA, at concentrations of 0.5 and 1 mM reduced the growth rates by > 85% at the three aW levels tested (0.995; 0.98 and 0.95). PP+butylated hydroxytoluene (BHT) or trihydroxybutyrophenone (THBP) were less effective in controlling growth, regardless of aW level. Combinations of PP+BHA reduced the fumonisin concentrations produced by F. verticillioides and F. proliferatum at 0.995 and 0.98 aW significantly. However, at low concentrations of antioxidants (0.5 mM) some stimulation in fumonisin production was observed with some treatments. The efficacy of the treatments was reflected in the impact on enzyme production. In the untreated control the highest total enzyme activity of three hydrolytic enzymes was observed at 0.995 aW after 96 h. All the antioxidant treatments alone or combined resulted in a significant reduction (P < 0.001) of the total enzyme activity at the aW levels tested. Only 10 mM THBP produced an increase in the total amount of N-acetyl-β-D-glucosidase by both F. verticillioides and F. proliferatum. For the three enzymes single factors: time, aW and antioxidant treatments, most two and all three way interactions were significant (P < 0.001). The use of combined mixtures of antioxidants could be a good strategy to diminish the entry of fumonisin into the animal feed and human food chains.

The relationship between teleomorphs of Cordyceps spp. and their presumed anamorphs have been investigated by analysis of 5.8S and ITS rDNA sequences. The morphological and sequence data confirm that Paecilomyceshawkesii is the anamorph of Cordyceps gunnii, while Cordyceps hawkesii is a synonym of C. gunnii, and P. gunnii is a synonym of P. hawkesii. The following presumed connections are also confirmed: Beauveria brongniartii is the anamorph of C. brongniartii, Metarhizium anisopliae var. majus is the anamorph of C. brittlebankisoides, Beauveria sobolifera is the anamorph of C. sobolifera, Mariannaea pruinosa is the anamorph of C. pruinosa, Paecilomyces militaris is the anamorph of C. militaris, and Hirsutellasinensis is the anamorph of C. sinensis. The other isolates sequenced are unlikely to be anamorphs of the teleomorphs from which they were isolated because the sequences from the culture and the teleomorph are quite different. 5.8S and ITS sequences provide useful information for establishing anamorph–teleomorph connections and assisting in the delimitation of species within Cordyceps.

Five fungal isolates, tentatively identified as belonging to Thysanophora, were re-examined to confirm their generic placement. DNA sequences from multiple loci were determined and compared to homologous sequences from other fungi. The Thysanophora-like isolates belong in the genus Penicillium on the basis of phylogenetic analysis of their gene sequences. Because these isolates have unique phylogenetic positions within Penicillium and have unique phenotypes we describe them as the new species P. boreae, P. subarcticum and P. canariense spp. nov. In addition, P. pullum sp. nov. is described for NRRL 721, which served as the typical isolate of P. fuscum in the monographic studies of Raper & Thom and Ramirez; however, the name P. fuscum has been applied and neotypified using a different specimen and NRRL 721 is markedly different phylogenetically from the neotype of P. fuscum.