This issue of Mycological Research News features: Electronic submission and tracking; Endocytosis in filamentous fungal hyphae; Cell wall associated enzymes; 33 threatened fungi in Europe; and A model for presenting systematic data on the Internet.

This part starts with the Society's 2003 Presidential Address by Neil A. R. Gow, and a review of the role of fungal secondary metabolites as inhibitors of plant pathogenic fungi.

Molecular phylogenetic studies address: Lasiosphaeria s. lat., Fusarium spp. on Gossypium, Guignardia isolates from Brazil, Colletotrichum isolates from Guyana, Venturia tremulae, Xylaria hypoxylon ITS1 variation, the recognition of arbuscular mycorrhizal fungi, and a new species of Umbelopsis.

The development of Scutellosphora reticulata, and mass culture of Metarhizium for biocontrol are described, and leaf-cutting ants are shown to retain fungal enzymes in their guts.

The following new scientific names are introduced in this part: Echinosphaeria, Hilberina, and Immersiella gens. nov.; Umbelopsis dimorpha sp. nov.; and Chaetosphaeria raciborskii (syn. Ophiochaeta raciborskii), E. canescens (syn. Sphaeria canescens), H. caudata (syn. S. caudata), I. immersa (syn. Lasisophaeria immersa), Lasiosphaeria lanuginosa (syn. Sordaria lanuginosa), L. rugulosa (syn. Cercophora rugulosa), Lasiosphaeris hirsuta (syn. S. hirsuta), and Ruzenia spermoides (syn. S. spermoides) combs. nov.

Mycology is changing as an era of extensive genome sequencing comes of age and provides vital information that enables questions to be addressed about fungi in all the major taxonomic groups. As technology transfer facilitates what was once only possible for a very small number of model species, it becomes possible to explore the biology and biodiversity of fungi as a whole. The availability of genome sequence information and reverse genetic technologies allows hypotheses that emerge from biological observations to be tested. Genomic and post-genomic technologies will underline the importance of fungi as excellent models for the study of fundamental biological phenomena. Two enduring areas of research in my own laboratory are described that are now being extended using post-genomic approaches. These projects relate to how fungal hyphae extend and guide their tips and secondly how plant pathogenic oomycete zoospores are guided on their journey to the plant surface.

The life-cycle of many plant-pathogenic fungi, especially those infecting aerial plant organs, contains several specific developmental stages. If these are sufficiently distinct in their physiology from vegetative hyphal growth, they present potential targets for non-fungitoxic plant protectants. The present review identifies such targets especially in the pre-penetration stages of the infection cycle of Magnaporthe grisea and other fungi infecting from air-borne spores. Examples of non-toxic natural products with activity against spore germination, attachment, appressorium formation, appressorium maturation and penetration of the host surface are given. In contrast, no substances selectively active against in planta growth or sporulation appear to be known. The selective activity of numerous secondary metabolites against specific infection stages without accompanying toxicity against vegetatively growing hyphae indicates a direction for the development of future natural product-derived fungicides which are more easily degraded in the environment and possess fewer non-target effects. Such substances are produced by many saprotrophic and endophytic fungi in pure culture. The paucity of data on the production of biologically active substances in natural situations limits the interpretation of their ecophysiological significance for the producer.

The current circumscription of Lasiosphaeria includes taxa with a wide variety of ascomatal walls, ascomatal wall vestitures, and ascospore morphologies and a broad range of putative anamorphs. Despite the complexity of morphological characters in the genus, species within Lasiosphaeria can be arranged into four groups based on ascospore morphology. Taxa which possessed ascospores in each of the four groups were used in phylogenetic analyses of partial nuclear large subunit (LSU) rDNA sequences to test the monophyly of the genus and determine relationships among its species. Lasiosphaeria was found to be highly polyphyletic in that species segregated into seven well-supported monophyletic clades dispersed among several orders. Three new genera, Echinosphaeria, Hilberina, and Immersiella, are erected for three of these clades while the genus Lasiosphaeris is reintroduced for a fourth clade. These data support Ruzenia as a previously established genus and the transfer of Lasiosphaeria raciborskii to Chaetosphaeria. The circumscription of Lasiosphaeria has been considerably narrowed to better reflect a natural classification. These taxonomic changes are additionally supported by a combination of morphological characters which are discussed in relation to the phylogenetic trees.

Fusarium isolates were extracted from stems and rhizosphere soils of 79 populations of four Gossypium species native to two regions of inland Australia in 2001. Six Fusarium species were isolated from 31 (3%) of the 919 stem samples. F. semitectum was predominant, occurring mostly in G. bickii populations and accounting for 81% of the isolates recovered. Twenty Fusarium species were isolated from 68 (87%) of the 78 composite soil samples, with F. solani (71%), F. compactum (8%), F. oxysporum (5%), F. graminearum (3%), and F. crookwellense (3%) being the most prevalent. Significant differences in the relative densities indicated that F. solani was more common in the soil from G. sturtianum populations than from G. bickii populations, and that F. crookwellense was more common in South Australian soils than in Queensland and Northern Territory soils. Fusarium oxysporum had a relatively greater relative density in the rhizosphere soils of G. australe plants than in that of sympatrically growing G. sturtianum plants. Fifteen (17%) of the 89 F. oxysporum isolates produced typical Fusarium wilt symptoms on cultivated cotton (G. hirsutum cv. ‘Siokra 1–4’), therefore they were classified as wild Fov. Soil samples collected from G. sturtianum populations in the Arkaroola-Leigh Creek region in South Australia had the highest incidence of wild Fov (24%). Two wild Fov isolates were similar in virulence to a cotton field Fov isolate in the glasshouse experiments, indicating that they could incite Fusarium wilt disease in cotton fields. The presence of wild Fov in native Gossypium populations suggests that the Fov occurring in Australian cotton fields may be of indigenous origins.

Phenotypic and genotypic variability of 18 endophytic Guignardia strains from different host plants (Anacardiaceae: Anacardium giganteum, Myracrodruon urundeuva, Spondias mombin; Apocynaceae: Aspidosperma polyneuron; Ericaceae: Rhododendron sp.; Fabaceae: Bowdichia nitida; Leguminosae: Cassia occidentalis; Rutaceae: Citrus aurantium) growing in different sites in Brazil was assessed by means of morphometric measurements and inter-single-sequence-repeat-anchored polymerase chain reaction (ISSR-PCR) amplifications of the DNA. Morphology of conidia and ascospores and growth rates of the Brazilian isolates corresponded well with those of G. mangiferae. Multiple correspondence analysis (MCA) of the ISSR-PCR data yielded three groups of strains, which did, however, not correspond either to the host or to the geographic origin. The same individual tree hosted genotypically different strains indicating multiple infections. Phylogeny based on ITS1-5.8S-ITS2 sequence analyses confirmed conspecificity of the Brazilian isolates with G. mangiferae (syn. G. endophyllicola).

The diversity and host specificity were studied of a collection of Colletotrichum strains derived from endophytic colonies in leaves of 12 tree species in the Iwokrama Forest Reserve, Guyana. Analysis included ISSR-PCR and RAPD molecular fingerprinting techniques, rDNA ITS sequencing and morphological and cultural characterization. Most strains belonged to one of two species, C. gloeosporioides and a further taxon which is probably referable to C. boninense. Almost no strains were found to be genetically identical, indicating that clonal reproduction does not play a prominent role. No degree of host specificity could be detected even at molecular fingerprint level. The implications for estimation of fungal diversity in closed tropical forests may be profound.

Genetic variation in three multiallelic loci was analysed with Temperature Gradient Gel Electrophoresis in order to assess the genetic population structure of Venturia tremulae var. tremulae in order to understand the evolutionary potential of the pathogen against resistance breeding. Also the identification of the fungus was verified with molecular analysis of reference isolates. The Fst and Gst values were very low indicating no substructuring or restrictions to gene flow between Fennoscandian populations of V. tremulae. The results imply high epidemiological efficiency of the fungus and therefore continuous breeding programme should be implemented for Venturia resistance of aspen.

During a survey of 375 strains of the Xylariales, one isolate (F127076) was observed to have an ITS1 size of 833 bp. This size exceeds the average ITS1 size in the Xylariales (mean=209±57 bp). Comparison of the DNA sequence with GenBank and with a proprietary DNA database revealed low homology with Xylaria hypoxylon ATCC 42768, and with one undescribed Xylaria species. When the ITS2 sequence was compared, these isolates were 96–98% homologous. Sequences of other variable genes confirmed the relatedness among these strains. A closer observation of the ITS sequence of this isolate revealed the presence of three repeated domains of 250 bp plus one truncated domain, showing 52–75% homology. Sequence similarity suggests that the repeated domain is derived from the fusion of the ITS1 with a DNA fragment derived from the γ-glutamyltranspeptidase gene. This example suggests that the rate of evolution of ITS1 can be independent of the rate of evolution of other genes, even when this variability is not a result of slipped strand misspairing events like in other Xylariales. This observation also indicates that recombination with other nuclear genes could participate in the evolution of the internal transcribed spacer.

Molecular techniques have become increasingly important for the identification of arbuscular mycorrhizal fungi (AMF). In this work Acaulospora longula and Glomus mosseae have been detected in plant roots from pastures using specific nucleotide primers for the two species. Part of the 5′ end of the large subunit of the ribosomal RNA gene was amplified by nested PCR and sequenced. The distribution of the fungi within three different plant species, Plantago lanceolata, Trifolium repens, and Holcus lanatus, and two different types of grassland, have been studied. Neither the fungi nor the plants showed specific preference for their symbiotic partnership.

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.

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.

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.

The new species Umbelopsis dimorpha sp. nov. was isolated from a soil sample in the Red Hills area of Mt Richmond Forest Park, in the northern part of the South Island of New Zealand. It has two kinds of pale pinkish sporangia: (1) single-spored, indistinguishable from those of U. versiformis; and (2) multi-spored, similar to those of U. vinacea. ITS sequences place the species in the immediate vicinity of the former species.