Colletotrichum lindemuthianum is a pathogen of the common bean plant (Phaseolus vulgaris) causing anthracnose. Large numbers of isolates can rapidly arise with different genetic and chromosomal compositions but their origin is unknown since sexual fruit bodies have only been found in the laboratory. We have recently described the occurrence of special kinds of hyphae that create anastomoses directly between conidia. In this work we show that conidial anastomoses can occur between two different Colletotrichum species. The implications of this observation on the generation of genetic diversity in these species are discussed.

Commercial Eucalyptus plantations provide an important source of hardwood for forestry industries, worldwide. Several species of Mycosphaerella are associated with a destructive Eucalyptus leaf disease known as Mycosphaerella Leaf Blotch (MLB). During 2000, a survey was undertaken in several commercial Eucalyptus growing areas of South Africa to determine the identity of the Mycosphaerella spp. contributing to outbreaks of MLB. Symptomatic leaf samples were collected from three major Eucalyptus growing areas and the Mycosphaerella spp. were isolated. Isolates were identified using morphology, ascospore germination patterns and sequence data from the ribosomal DNA operon. Six species, namely M. ellipsoidea, M. irregulariramosa, M. juvenis, M. lateralis, M. marksii, M. nubilosa, as well as a new species, described here as M. fori sp. nov., were recognized. Mycosphaerella nubilosa was the most common species isolated from commercial plantations, particularly on E. nitens, and appears to be the dominant species contributing to MLB. Data obtained in this study show that MLB is caused by a complex of species contributing to disease outbreaks in South Africa.

The development of the extraradical mycelium and auxiliary cells and spore production of Scutellospora reticulata in association with Ri T-DNA transformed carrot roots was followed under root-organ culture conditions. Extraradical mycelium development followed classical lag-exponential-plateau phases, with an additional late decline phase in number of auxiliary cells. Spore production started in parallel with a critical extraradical mycelium biomass produced, continued long after root growth ceased and during the late decline in auxiliary cells number. Isolated auxiliary cells were shown to exhibit hyphal re-growth, but not root colonization, either in situ or in vitro. These results showed that root and extraradical mycelium development were intimately associated in a sequence where both grew together during active root growth, followed during root aging by a period in which only the fungus developed. Spore production appeared dependent on a critical extraradical mycelium biomass and on the re-allocation of resources from both the intraradical mycelium and the auxiliary cells via the hyphal network.

The microscopic structure of herbarium material of alpine and arctic species of Russula sect. Xerampelinae from Europe and Greenland was studied. Based on our observations two taxa with prevailingly red pilei are accepted from the area: R. subrubens and R. pascua. Other related species occurring in arctic areas are R. cicatricata with a coppery coloured pileus and R. clavipes with a prevailingly greenish olivaceous pileus. As a consequence of the study of type material, R. chamiteae var. chamiteae and R. chamiteae var. microsperma are synonymized with R. subrubens. No European collections could be referred to R. oreina, and accordingly we suggest that this species is absent from Europe.

The aim of the present work was to determine the identity and molecular relationships between 127 strains of dark septate (DS) fungi isolated from healthy root tips, decayed coarse roots, live healthy-looking stems, coarse (stumps, snags and logs) and fine (tree branches and tops) woody debris in temperate-boreal forests in Sweden and Lithuania. Sequence analysis of ITS rDNA was used to identify the fungi. In a neighbour-joining similarity tree, all sequences were grouped into five distinct clusters. Within each of these, ITS rDNA sequence variation consisted of 2–18 nucleotides, corresponding to 1–3% of their total length. The four least variable clusters were supported with high bootstrap values of 86–100%. Comparisons with the sequences in the GenBank database showed that all our strains had a 95–100% homology with identified Phialocephala species, and they were thus assigned to this genus. The representatives of two clusters were identified, as P. fortinii and P. dimorphospora. The representatives of three remaining clusters were defined as Phialocephala sp. 35, Phialocephala sp. 6 and Phialocephala sp. 18. Within each of these clusters, ITS rDNA sequence uniformity was higher than that observed within P. fortinii and P. dimorphospora. Consequently, their clusters were most discrete, supported with bootstrap values of 100%. Genetic variation in the five distinguished Phialocephala species and their possible ecological roles are discussed. Phialocephala sp. 6 was confined to healthy root tips of conifers. P. dimorphospora was only associated with dead woody tissue of P. abies. P. fortinii, Phialocephala sp. 18 and sp. 35 were isolated from both dead and living conifers and Betula pendula. In conclusion, the present study revealed the ability of fungi from the genus Phialocephala to colonise and persist in live and dead trees under strikingly different ecological conditions.

In Australia, the endemic fungus Plectosporium alismatis (syn. Rhynchosporium alismatis) has potential use as a mycoherbicide for several species in the Alismataceae, a family of aquatic and semi-aquatic marsh herbs, which are considered to be important weeds in rice crops. Of five species identified in south-eastern Australia where rice is grown, two species, Sagittaria graminea and Sagittaria montevidensis are resistant (non-hosts), and no records of P. alismatis on these species have been reported. To better understand the interactions that lead to resistance in these pathosystems, the infection process of the fungus was studied on these species and also on the host Alisma plantago-aquatica, using light, fluorescent and scanning electron microscopy. On all three species both conidial germination and appressorium formation commenced within 6 h of inoculation with greater than 50% of conidia elongating to form germ tube structures and associated appressoria 12–18 h post inoculation. Germ tube elongation and appressorium formation occurred randomly over the leaf surface. Direct host penetration was facilitated by the production of penetration hyphae that emerged from beneath appressoria. Penetration sites were clearly identified by the presence of spherical holes 0.25–0.5 μm in diam, and were frequently accompanied by resistance reactions in non-host species. Visible symptoms of disease occurred 4–6 d after inoculation of susceptible (host) species.

The identification of plant-associated isolates of Aphanomyces spp. has been mainly based on morphological characters. These types of features, however, can be unreliable due to their high variation and degree of overlap between different taxa. In this work, strains of Aphanomyces, with plant pathogenic and non-pathogenic characteristics, derived mainly from the roots of several leguminous crops in Sweden, as well as a number of reference strains of A. euteiches, A. cladogamus and A. cochlioides were compared by morphology, AT-rich DNA RFLPs and sequence analysis of the total ITS/5.8S rRNA gene region. Parsimony analysis of the sequence data of the total ITS region of 21 strains separated the taxa at the specific level, while two intra-specific groups were also detected within A. euteiches. One comprised all pathogenic isolates of A. euteiches from Sweden, together with two isolates from France and the USA. These isolates formed a homogenous group with identical ITS regions and a single AT-rich DNA RFLP banding pattern. The second ITS subspecific group included reference strains of A. euteiches with preferential pathogenicity to bean and alfalfa, all of which originated from the USA. The bean and alfalfa pathotypes were further distinguished by their different AT-rich DNA RFLPs. The non-pathogenic isolates of Aphanomyces from Sweden associated with the roots of several legumes, formed a genotypically uniform group with an identical ITS sequence and a single AT-rich DNA RFLP pattern. The ITS sequence of this group was identical to that of reference strains of A. cladogamus, suggesting that the non-pathogenic isolates belonged to this species. Intra-specific AT-rich DNA banding profiles were also obtained for isolates of A. cladogamus and these patterns corresponded well to the original hosts.

The fungi associated with diseased and healthy shoots of young, planted Betula pendula were studied at five sites in Scotland where crown die-back of birch is occurring. At each site, 30 diseased and 30 healthy shoots were sampled twice, with 1 yr-old shoots collected in May 2002, and 4–5-month-old shoots collected in September/October 2002. Overall, 34 different fungal species were recorded, with 92% and 60% of all diseased and healthy shoot pieces, respectively, colonised by at least one fungal species. The main colonisers of both diseased and healthy shoots were Melanconium bicolor, Discula betulina and Godronia urceolus, and the fungi most frequently found on diseased shoots only included Marssonina betulae and Fusarium avenaceum. The pathogenicity of these fungi was tested on seedlings of B. pendula and B. pubescens. Melanconium bicolor required a wound for lesion development on both birch species and caused larger lesions on B. pubescens than on B. pendula. Discula betulina caused lesions on stems and shoots of both birch species, including non-wounded current shoots. Marssonina betulae caused lesions and die-back of wounded and non-wounded current shoots of B. pendula seedlings. This fungus was not pathogenic on B. pubescens. Fusarium avenaceum caused restricted lesions on the main stems of both birch species. Godronia urceolus was not pathogenic on either birch species. Further work needs to focus on the role of these fungi in causing crown die-back of young, planted B. pendula in Scotland.

Mycological Research108 (2): 189–197 (February 2004).

Growth and interspecific interactions of the rare oak polypore Piptoporus quercinus

Paul WALD, Martha CROCKATT, Victoria GRAY, and Lynne BODDY

Figures 3–17 should have been reproduced as a full colour plate. The publishers would like to apologise to the authors and their readers for this error.

Downy mildew of oilseed poppy (Papaver somniferum) has become a serious disease issue for the Tasmanian poppy industry since its first record in 1996. Previous reports have reported the pathogen as Peronospora arborescens, which is differentiated from the related species P. cristata, also known to infect Papaver spp., by conidium dimensions alone. This study investigated the taxonomic status of the downy mildew pathogen, using both morphological characters and molecular analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). The inherent variability of conidium dimensions made differentiation of species difficult. Sequence homology and phylogenetic analyses of the ITS region showed the pathogen to be more closely related to P. cristata than P. arborescens. It is therefore proposed that downy mildew of oilseed poppy in Tasmania be reattributed to the pathogen P. cristata. In addition to this work, PCR primers have been developed for the specific detection of the downy mildew pathogen in Tasmania.

It is difficult to accurately identify Mycosphaerella species associated with leaf diseases of Eucalyptus based on morphological characters, as there is considerable overlap between very similar species and subspecies, and isolation from the host is not easy. Thus, a PCR and RFLP assay based on the ITS region of nr DNA was developed for the rapid detection and differentiation of M. nubilosa, M. cryptica and two non-sporing unidentified Mycosphaerella species isolated from the foliage of trees in resistant and susceptible families of E. globulus in a seed orchard at Kinglake West, Victoria, Australia. The M. nubilosa primer pair MNF/MNR was highly specific. A PCR-RFLP system based on the primer pair MCF/MCR, coupled with two restriction enzymes (DdeI and Tru1I), differentiated M. cryptica, M. nubilosa, M. tasmaniensis and M. aff. vespa. One of the unidentified field-isolated Mycosphaerella species was identified as M. grandis on the basis of ITS sequence data while the other species remains unidentified. A PCR-RFLP system based on the primer pair U1F/U1R, coupled with the restriction enzyme StyI, differentiated between the two unidentified species. Unexpectedly, unlike isolation and culture studies, these assays detected M. nubilosa, M. cryptica and M. grandis in all single lesions examined on both juvenile and adult leaves, and on both highly resistant and highly susceptible E. globulus trees at this site.

A rust fungus found on cultivars of Kalanchoe blossfeldiana (Crassulaceae) is described as a new species, Aecidium kalanchoe sp. nov., and compared to the other described rusts on members of the Crassulaceae. Only one other rust is known to parasitize Kalanchoe spp. A DNA sequence of A. kalanchoe suggests that the teleomorph is related to Puccinia.

Phyllosticta capitalensis (teleomorph Guignardia mangiferae) occurs as a foliar endophyte in woody trees belonging to different families of both temperate and tropical regions. We isolated this endophyte from plants in different habitats, such as mangroves, dry deciduous forest, moist deciduous forest and semi-evergreen forest. This endophyte was found to produce a black pigment that was characterized to be melanin based on UV-visible, IR and ESR spectra and chemical tests. Tricyclazole, a specific inhibitor of pentaketide melanin biosynthesis, inhibited synthesis of the pigment indicating it is a 1-8, dihydroxynaphthalene. This appears to be the first report of such a melanin in Phyllosticta or other foliar endophytes. Melanin in the hyphae of P. capitalensis may be responsible for the success of this fungus as a cosmopolitan endophyte, since melanin is known to enhance the survival capability of fungi in stressful environments.

Currently, mycopesticide development for locust and grasshopper control depends on aerial conidia or submerged spores of entomopathogenic fungi. In our study, the production of submerged conidia of Metarhizium anisopliae var. acridum (IMI 330189) was investigated in a liquid medium containing 3% biomalt and 1% yeast extract (BH-medium). The effects of freeze and spray drying techniques on the quality of submerged conidia were determined. The influence of different additives on the viability of fresh submerged conidia and their suitability for oil flowable concentrate formulation development was assessed. In a BH medium maintained at 180 rev min−1, at 30 °C for 72 h, IMI 330189 produced a green pigmented biomass of submerged conidia whereas in Adámek medium it produced a yellowish biomass of submerged spores. The spore concentration was high in both media; however, the size of the spores produced in the BH medium was significantly lower than those produced in Adámek medium (P<0.001). Submerged conidia can be effectively dried using either freeze or spray drying techniques. The viability and speed of germination were significantly affected by the drying and pulverizing process (P<0.001). The initial viability was significantly higher for spray-dried submerged conidia than for freeze-dried spores. Pulverizing of freeze-dried submerged conidia reduced the speed of germination and the viability by 63–95%. Dried submerged conidia can be stored over 45 wk at low temperatures (<10°) without suffering a significant loss in viability. Furthermore, we have identified carriers that are suitable for oil flowable concentrate formulation development.

Mycological Research108 (1): 5–13 (January 2004).

Presidential Address

New angles in mycology: studies in directional growth and directional motility

Neil A. R. GOW

Figures 2 and 3 should have been reproduced as full colour figures on page 9 of the January issue. Pages 9 and 10 have been reprinted as they should have appeared on the following pages so that readers may replace the pages in their January issue if so desired.

The publishers would like to apologise to the author and their readers for this error.

Leaf-cutting ants finely fragment the leaf material that they bring to the nest and place faecal droplets on this substrate before incorporating it in the upper part of the fungus-garden. The faecal droplets contain enzymes of which some have been shown to be of fungal origin. Here we explicitly address the enzymatic activity of faecal droplets in the leaf-cutting ants Acromyrmex echinatior and Atta colombica. We used isoelectric focusing and specific staining to show that faecal droplets of both species contain carboxymethylcellulases, laccases, proteases, and pectinases (both pectin esterases and pectin lysases) and we demonstrate that these enzymes originate from the symbiotic fungus and not from the ants themselves. The level of activity of fungal pectin lyase in faecal droplets indicates that fungal enzymes may be protected and possibly concentrated during their passage through the ant gut. This would imply that enzymes that are transferred by ants from mature parts of the fungus gardens may play an important role for the colonization of new substrate by new mycelium of the same fungal clone.

Mycological Research108 (2): 206–213 (February 2004)

Description and affinities of a new sequestrate fungus, Barcheria willisiana gen. et sp. nov. (Agaricales) from Australia

Teresa LEBEL, Deanne K. THOMPSON and Frank UDOVICIC

On p. 211 in this paper, Fig. 2 was inadvertently printed in black and white and not in full colour as intended. The correct full-colour version is therefore reproduced below. The publishers would like to apologise to the authors and readers for this error.

Mycological Research108 (5): 583–589 (May 2004)

Some Chytridiomycota in soil recover from drying and high temperatures

Frank H. GLEASON, Peter M. LETCHER and Peter A. McGEE

In this paper, on p. 584, left-hand column, line 14 up, ‘24 h’ should be corrected to ‘48 h’. In addition, on p. 586 the legend to Fig. 1 (b) should read ‘other thalli’ and not ‘another thallus’.

The authors and editors regret any confusion overlooking these points in the proof has caused.

Mycological Research108 (5): 533–570 (May 2004).

Taxonomy of the non-yellow species of Rhizocarpon (Rhizocarpaceae) in the Nordic countries, with hyaline and muriform ascospores

Per IHLEN

Owing to a change in the pagination of this paper after the original proofs were returned, the page references in the index to names treated were all two pages out. The correct page numbers are included in the replacement Table presented here

The entomopathogenic fungus Metarhizium anisopliae was physiologically manipulated by culturing in liquid culture under a range of water-stress conditions (0.98, 0.97 and 0.96 water activity, aw) imposed by either PEG 200, KCl or NaCl at 25 °C to optimise blastospore production and quality in terms of accumulation of endogenous compatible solutes and germinability. Optimum spore yield occurred at 0.98aw, when PEG 200 was the solute. Blastospores produced under different water-stress levels were subjected to hypo-osmotic and iso-osmotic washing treatments before quantification of endogenous sugar alcohols (polyols) and germinability studies. Endogenous amounts of the low molecular weight polyol erythritol were greatly affected by culture age, water-stress and hypotonic or isotonic washing treatment. Endogenous erythritol in blastospores produced under 0.98 and 0.97aw increased with culture age. Osmoprotection (washing with isotonic PEG 200 solution) of blastospores produced under all water-stress conditions resulted in retention of higher amounts of erythritol. Increased endogenous retention of the high molecular weight polyol mannitol was also observed with an isotonic washing treatment but only in blastospores produced under intermediate water-stress (0.98 and 0.97aw). Germination of all treatments was >90% on a medium with freely available water. Under water-stress conditions (0.96aw) only 10% of unmodified blastospores washed with water germinated. However, those grown under modified water availability conditions (0.98aw) and washed with isotonic solutions had significantly improved germination (38–90%). Blastospores produced at [les ]0.97aw washed with isotonic solutions had decreased germination. These results could have significant implications for conserving ecophysiological quality of fungal biocontrol propagules during harvesting and have an impact on storage and formulation.