This month Mycological Research News features the role of mitogen activated protein kinase genes in the pathogenicity of fungi, and the importance of hydrophobins.

The 16 papers in this issue cover the molecular phylogeny of Schizopora, a revision of some species in Fusarium sections Fusarium and Roseum by RFLP methods, and an investigation of the differences in the ITS regions of special forms of F. solani. Ecogeographical variation in Pleurotus eryngii is documented, and the effects of hydroxyl radical scavengers on sclerotial formation in two plant pathogens demonstrated.

Some plant pathogenic fungi are eaten by collembolans, but others are lethal to these organisms. Licuala palms prove to be rich in endophytic fungi, and cultural groups of the endophyte Phialocephala fortinii are compared by molecular methods. An isolate of Flavodon flavus with potential applications in bioremediation has been discovered, and oosporein found dominant in Beauveria brongniartii products. The behaviour of Aschersonia aleyrodis conidia on different hosts has been investigated, and two kinds of conidia have been discovered in Conidiobolus adiaeretus.

The discovery of a high α-amylase producing Aspergillus oryzae strain is reported, Melampsora larici-tremulae has been successfully cultured, and the ‘gun cells’ of Haptoglossa dickii have been investigated ultrastructurally.

The issue concludes with an obituary of Guido Pontecorvo.

The following new scientific names and introduced: Fusarium aywerte (syn. F. avenaceum subsp. aywerte), and F. nurragi (syn. F. avenaceum susbsp. nurragi) combs. nov.

A phylogenetic analysis based on internal transcribed spacer regions of the nuclear ribosomal RNA region (ITS) sequences has been undertaken for species in the genus Schizopora. Four known species were studied, viz. S. radula, S. paradoxa, S. flavipora, S. nothofagi, and a hitherto undescribed species from Taiwan. Allopatric differentiation was apparent in S. radula, for which several geographically representive samples were available. Among these, ITS sequence data obtained from S. radula isolates from British Columbia and Australasia were identical. All previously recognised Schizopora species were well separated from each other with respect to their ITS sequences. Mating compatibility tests also showed complete reproductive separation between species, but intercompatibility between cultures from the same species, irrespective of geographical origin. Overall, the morphology of basidiomes of S. radula from New Zealand differs only in minor respects from those of European and Argentinean origin, but shows a higher degree of variability than described for European specimens.

The genetic relationships of 56 isolates from the taxa traditionally grouped in Fusarium sections Fusarium (syn. Discolor) and Roseum were studied using the Restriction Fragment Length Polymorphism (RFLP) technique, by Southern hybridisation with random genomic and mitochondrial DNA probes originating from Fusarium species. Pairwise distances between taxa were calculated from the 957 RFLP bands scored on autoradiograms, using Dice's coefficient in the RAPDistance computer program. A strong genetic relationship was observed between F. graminearum, F. culmorum and F. crookwellense. However, the morphologically similar taxon, F. pseudograminearum shared only approximately 40% of genomic DNA RFLP bands with these taxa, demonstrating affinity, but less direct genetic similarity. Of all taxa examined F. pseudograminearum and F. graminearum shared the greatest similarity in mitochondrial DNA RFLP patterns. F. avenaceum subsp. avenaceum, subsp. aywerte and subsp. nurragi displayed very little genetic resemblance with each other, or with F. heterosporum and the cereal infecting pathogens. F. torulosum was closest genetically to subsp. avenaceum, with approximately 22% of genomic DNA RFLP bands in common. On the basis of these results F. avenaceum subsp. aywerte and subsp. nurragi are elevated to species rank, as F. aywerte comb.. nov. and F. nurragi comb. nov., and F. avenaceum subsp. avenaceum is returned to its former species status.

The nucleotide sequence of the internal transcribed spacer region of the ribosomal RNA gene (rDNA-ITS) was obtained for strains belonging to 10 special forms (f. spp.) of the phytopathogenic fungus Fusarium solani (teleomorph Haematonectria haematococca). Phylogenetic analysis of nucleotide sequences of the rDNA-ITS region showed that most clusters were composed of strains belonging to the same special form. F. solani f. sp. eumartii and f. sp. phaseoli were excluded from the cluster composed of all other special forms. In order to use the molecular data to identify each special form, several restriction enzymes specific for each special form were selected from the mapping data. The digestion pattern of the rDNA-ITS region with these restriction enzymes was able to distinguish F. solani f. spp. phaseoli, cucurbitae race 1, batatas, piperis, eumartii, and xanthoxyli. Although f. spp. mori, robiniae and pisi were not differentiated by restriction analysis, they were separated in the phylogenetic tree.

The geographical distribution and ecological habitats of the Pleurotus eryngii complex in Israel are described from a study of 60 genotypes from 10 populations. Both MEA and PDA media were suitable for growth of all genotypes at all temperatures tested (4–37 °C). There was a high correlation between a coefficient of growth and the mean colony diameter growth rate. All genotypes reached the maximum growth at 27°. Growth rate at 30° was greater than at 19°. We found highly significant (P < 0.0001) variability among growth rates of Israeli genotypes, indicating ecogeographical differences among populations. The growth rate of 12 European genotypes from the Ukraine and Slovakia was higher than most of the Israeli genotypes when grown at 27° (non-stress conditions), but Israeli genotypes tolerated 37° (stress conditions) better, and recovered faster than European populations when returned to 27°. We conclude that Israeli genotypes are better adapted to hot and dry climates than European genotypes. Based on multiple regression analyses, strong correlations were found between relative humidity and rainfall parameters, but not temperature, of the locations from which Israeli isolates were collected, and their growth rates. This indicates that, paradoxically, relative humidity and rainfall have a stronger effect than temperature on the adaptability of this complex to different environments.

The effect of hydroxyl radical scavengers dimethyl sulphoxide, p-nitrosodimethylaniline, ethanol, benzoate, salicylate and thiourea was studied on sclerotial differentiation and growth of Sclerotinia sclerotiorum and Rhizoctonia solani. There is a correlation between both scavenger concentration and scavenger-hydroxyl radical reaction rate with delay and inhibition of differentiation at growth-noninhibiting scavenger concentrations. Growth-inhibiting scavenger concentrations further increased delay and inhibition of differentiation, and eventually stopped fungal growth, acting as antifungal antioxidant alternatives to traditional fungicides. p-nitrosodimethylaniline (with the highest hydroxyl radical reaction rate) was the most effective inhibitor of sclerotial differentiation and growth. The results strongly support the theory that oxygen free radicals induce differentiation in sclerotium-producing phytopathogenic fungi.

Interactions between springtails (Onychiurus armatus, O. tuberculatus, Folsomia candida) and plant pathogenic fungi (Gaeumannomyces graminis var. tritici, Fusarium culmorum, Bipolaris sorokiniana and Rhizoctonia cerealis) living in the same soil layer were investigated under laboratory conditions. The fungi are responsible for the foot and root disease complex of winter cereals and can cause serious reduction in yield. Since these species coexist in agricultural soils, feeding preference tests were performed in such a way that the springtails were allowed to interact simultaneously with all the tested fungi. O. armatus, O. tuberculatus and F. candida fed on the mycelia of G. graminis var. tritici, F. culmorum and R. cerealis: in the first hours of the trials individuals of all springtail species distributed themselves among the colonies, though moving from one to the other. Subsequently F. culmorum mycelium became the preferred food of all species tested; however, the other two fungi continued to be consumed. Mycelia of G. graminis var. tritici, F. culmorum and R. cerealis were shown to be an adequate food source for reproduction of Folsomia candida. Bipolaris sorokiniana mycelium had both repellent and lethal effects on F. candida and O. armatus, whereas this fungus was lethal, although not repellent, for O. tuberculatus. Long-term experiments on F. candida indicate that conidia of B. sorokiniana were eaten and proved to be a sufficient diet for reproduction.

Endophytic fungi were isolated from three unidentified Licuala sp. palms in Brunei Darussalam and from three L. ramsayi palms in Australia. Endophytes were very common in both species, with overall colonisation rates of 81–89%. Taking into account a lower sampling frequency in Australia, endophyte diversity was similar in the two Licuala species. The endophyte assemblages examined were very diverse, consisting of 75 fertile species and 60 sterile morphospecies. The endophyte communities of both palms were composed of a single, dominant xylariaceous species, approximately ten less common but equally ubiquitous species and a large number of species occurring at very low frequencies. Differences were observed between the endophytic mycotas of different palm tissues and of tissues of different ages. The results presented suggest that most of the endophytes entered the petiole via the leaf and that transmission of palm endophytes is likely to be horizontal (via airborne propagules) rather than vertical (via seed). Seasonal differences were not observed in Brunei. Increased sampling effort could be expected to yield more endophyte taxa in both species investigated.

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.

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.

Oosporein was the only major secondary metabolite produced by three commercial isolates of the entomopathogenic fungus Beauveria brongniartii in submerged cultures and on sterilised barley kernels. None of the other toxins (bassianin, beauvericin and tenellin) normally produced by Beauveria species were detected by sensitive HPLC and MS techniques. The maximum amount of oosporein produced in batch reactors was 270 mg l−1, after 4 days incubation, while that produced on sterilised barley kernels ranged between 2.0 and 3.2 mg kg−1, after 14 days incubation. The mean amount of oosporein detected in cockchafer larvae infected with B. brongniartii was 0.23 mg. Melocont®-Pilzgerste, a commercial product based on B. brongniartii, was not phytotoxic to Lepidium sativum and Phleum pratense nor were fungal metabolites detected in these indicator plants. No systemic effects of oosporein were observed in treated pasture turf maintained for several months in the greenhouse.

Persistence of Aschersonia aleyrodis, a fungal pathogen of whitefly, was studied on cucumber, gerbera and poinsettia. Germination capacity and infectivity of conidia, which stayed on the plants for up to 1 month, were assessed. Average germination of conidia on the leaves was low (< 14%), whereas most of the conidia transferred from the leaf to water agar were viable, even after having been on the leaf surface for 1 month. Germination capacity was highest on cucumber, followed by poinsettia and lowest on gerbera. On cucumber leaves, conidia stayed viable and were able to infect 90% of whitefly nymphs 31 d after spore application. On gerbera, germination capacity decreased considerably from 80% (day 0) to 40% (day 31). This was reflected in nymphal mortality, which declined from 75% to 40%. Despite the high germination capacity (60%) of conidia on poinsettia after an exposure of one month, nymphal mortality decreased from 70% at the day of spore application to 10% after 3 d at leaf surface, and remained low throughout the monitoring period. Relations between germination capacity, infectivity and the host plant environment such as phyllosphere microorganisms, secondary plant metabolites and microclimate are discussed.

The development and selection of a morphological variant were systematically observed during continuous cultures of Aspergillus oryzae A1560 carried out at a dilution rate of 0.1 h−1. The selection was monitored by following the changes in the population morphology and in the α-amylase production during these experiments. A mathematical model for the selection was proposed assuming that the inoculum consisted of a mixed population. Growth, glucose uptake and α-amylase production for the selected morphological variant were further investigated in glucose-limited continuous cultures carried out at dilution rates ranging from 0.06 to 0.2 h−1. The selected variant was distinguished from the parental strain in three main aspects: (1) a higher capacity of α-amylase production at all dilution rates investigated; (2) a 36% higher maximum specific growth rate; and (3) a more sparsely branched mycelium, with fewer aerial hyphae and loss of sporulation ability on solid media.

Axenic cultures of the aspen rust Melampsora larici-tremulae were established for the first time by seeding aeciospores artificially produced on larch onto three chemically defined media. Cultures were maintained for 9 months and evaluated for their appearance, growth rates and sporulation ability. Two types of colonies were observed. One, white and fluffy tending to felty, did not sporulate in culture. The other, white-orange with a more compact aerial mycelium, sporulated profusely producing various spore like bodies and other unusual structures. An initial lag phase, with reduced growth, characterised primary rust cultures in the first 4–5 weeks. After about one month, cultures seemed adapted to utilising exogenous nutrients for sustained growth and their development rate increased substantially. As a result of selection under unusual growing conditions, fast-growing genetic variants were also observed in the nutrient agar. Growth on all the three test media, containing different organic and inorganic constituents, suggested that nutritional requirements were non-specific. The importance of axenic cultures in the study of the nutritional requirements of aspen rust and the potential of these investigations to elucidate some physiological and genetic aspects of the host-parasite relationship are discussed.

Haptoglossa dickii is a biflagellate zoosporic parasite of bactivorous nematodes. The walled encysted zoospores germinate more or less synchronously to produce specialised infection cells known as gun cells. This paper documents the changes in the main cytoplasmic organelles, namely the nucleus, Golgi body, mitochondria, lipid droplets and dense-body vesicles, from the onset of encystment until the formation of the mature gun cell. The septum-delimited gun cells show a marked polarity in the distribution of their organelles from their inception, which seems in part determined by the temporal order by which the main organelles migrate out of the cyst and into the gun cell initial. In this species the majority of dense-body vesicles and mitochondria precede the nucleus and lipid droplets. The nucleus remains more or less central throughout the remaining course of gun cell differentiation. The single nucleus associated Golgi body changes its orientation to track (possibly even determining) the spatial position of the ingrowing injection tube. The mitochondria fuse to form one or more complex reticulate structures which are aligned close to the injection tube throughout its formation and which in the mature cells form a fine network entwined around the fully differentiated tube. The vesicles containing electron-dense inclusion granules (dense-body vesicles) are initially concentrated towards the gun cell anterior, but later migrate to the posterior end of the cell and fuse to give rise to the basal vacuole. Some of the likely functional aspects of these cytoplasmic changes are discussed.

We report the ability of Conidiobolus adiaeretus to form repetitional microconidia and capilliconidia. Detailed descriptions of development and germination are given. This is the first report of any entomophthoralean fungus producing both these alternative conidial types. This cuts across current definitions of subgenera in Conidiobolus which are based on the absence of these conidial types or on the presence of either microconidia or capilliconidia but not both. Co-occurrence of both these spore types, along with the unusual mode of formation of the microconidia, and the ability to derive capilliconidia directly from the latter, reinforce other features which set C. adiaeretus apart. Taxonomic, evolutionary and ecological implications are briefly discussed.

Guido Pontecorvo, ‘Ponte’ to all who knew him, was born in Pisa, Italy, on 29 November 1907. His death on 25 September 1999, in his beloved Swiss mountains, marks the loss of a scientist whose breadth and vision had major impacts on genetical thought and experimentation.

After a classical education at Pisa lycee, he studied agricultural sciences at Pisa University (1924–1928) and later took postgraduate courses, including a diploma in silkworm breeding, in Milan and Pisa. His first research was in Florence, at the Agricultural Advisory Service for Tuscany; he worked on the beautiful Chiano breed of cattle for which he retained a strong affection. The breadth acquired in this and later periods was of lasting value. It had a lively impact on undergraduate courses in Glasgow, and for members of his first research team, all concentrating on microbial genetics, Ponte drew on a wealth of relevant references from his background, and applied ready corrective measures if he suspected a blinkered outlook.