Net blotch caused by Pyrenophora teres is a serious disease of barley in many cereal production areas world-wide, including the Western Cape province of South Africa. The pathogen occurs as two forms, P. teres f. teres, which produces net-blotch symptoms, and P. teres f. maculata which produces leaf spots. Pyrenophora japonica and P. hordei, which have also been reported in South Africa, also produce spots on susceptible barley cultivars. Using RAPD markers, spot-forming isolates from the South African population were found to be relatively uniform. Single ascospores were obtained from pseudothecia after in vitro mating had occurred between a verified P. teres net-blotch isolate from Denmark and a representative Pyrenophora leaf spot isolate from South Africa. Using amplified fragment length polymorphism (AFLP) and RAPD markers, recombination was demonstrated in the progeny which had DNA banding patterns different from the two parental isolates. Pathogenicity trials also confirmed that recombination had taken place during mating. Inoculations were conducted on differential cultivars susceptible to the net-blotch or leaf spot forms. The two parents induced typical net-blotch or leaf spot symptoms whereas the progeny mostly induced a jagged spot symptom on each cultivar. Fungicide sensitivity tests using the ergosterol biosynthesis inhibitors triademinol, bromuconazole and triticonazole showed that, due to recombination, some progeny could have increased resistance to these fungicides. Due to mating and subsequent recombination between a net blotch isolate of P. teres and a representative leaf spot isolate, it was concluded that the latter was P. teres f. maculata. These results contrast with the earlier belief that Pyrenophora leaf spot isolates in the Western Cape are P. japonica and P. hordei.

Three new species of Stenella, S. cassiicola, S. eugeniicola and S. rhododendricola, occurring on Cassia fistula, Eugenia heyniana and Rhododendron campanulatum, respectively, are described and illustrated.

Phaeoramularia bauhiniae, P. marsdeniae and P. tephrosiicola sp. nov., on Bauhinia bahli, Marsdenia verticulata and Tephrosia hirta, respectively, are described, illustrated and compared with similar taxa. Keys have been provided to distinguish Phaeoramularia spp. on Asclepiadaceae and Fabaceae.

The genetic relationships between several morphological groups recognized within Colletotrichum acutatum sensu lato were investigated using RAPD analysis and vegetative compatibility analysis. Isolates were examined from fruit rots originating in New Zealand and Australia, from Lupinus spp. in New Zealand, Canada, France and the U.K., and from Pinus radiata in New Zealand and Australia. The genetic distinctness of the groups recognized morphologically is confirmed. Two genetically distinct groups of C. acutatum-like pathogens are recognized from lupin, one comprising isolates from New Zealand and the U.K., the other isolates from Canada and France. C. acutatum f. sp. pineum isolates from New Zealand and Australia form two genetically distinct groups.

Fungi isolated from the leafy liverwort Cephaloziella exiliflora collected in Australia and continental Antarctica were compared with Hymenoscyphus ericae using internal transcribed spacer (ITS) region DNA sequences. The isolates displayed <2·1% sequence divergence within the ITS region, indicating that the endophytes from C. exiliflora are probably H. ericae. The data significantly extend the known host range and geographical distribution of H. ericae and indicate that the fungus has a global distribution.

Strains of Trichoderma harzianum possess biocontrol capabilities. As background for identification of strain-specific markers for monitoring strains of interest, the relationship of strains designated as T. harzianum, including representatives of three biological forms Th1, Th2 and Th3, were analysed by Universally Primed PCR, UP-PCR, using UP and random primers. Cross dot blot hybridization of UP-PCR products generated with either of two different UP primers or a random primer showed unequivocal differences among strains. Using this approach, T. harzianum strains were distributed into two different genotypic groups. One of the T. harzianum groups included forms Th1 and Th2 while the other group accounted for the Th3 form. The relatedness of strains of each group was estimated by UPGMA analysis based on markers revealed with three primers. It was found that both genotypic groups are heterogeneous, and Th2 form strains definitely cluster together with those of Th1. Division of the three biological forms of T. harzianum into two groups was also supported by rDNA-ITS1 analysis, where Sau3A digestion of the amplified ITS1 region gave a restriction fragment profile specific for each genotypic group. Two strains with known biocontrol capabilities were found to relate to the genotypic group containing Th1 and Th2 forms and, based on variation within this group, to belong to a homogeneous group of form Th1 strains. The robustness and reliability of UP-PCR fingerprinting were demonstrated by obtaining identical banding profiles using different conditions for PCR in different laboratories.

Accumulation and transformation of tellurite (TeO32−) by a species of Fusarium and Penicillium citrinum was examined using both solid and liquid Czapek Dox medium. In liquid medium, tellurite partitioned into soluble and insoluble species, and in tellurite-containing (1 mM) liquid medium at pH 6, approx. 60% of added tellurite precipitated after 48 h. Experiments showed that in liquid medium containing 1 mM sodium tellurite, the Fusarium sp. accumulated a maximum of ∼0·6 μmol Te (mg D.W.)−1 after 48 h. P. citrinum accumulated a much lower amount of tellurium, ∼0·07 μmol (mg D.W.)−1 falling to <0·02 μmol (mg D.W.)−1 after 48 h. Both organisms showed marked differences in the pattern of pH change of the medium, with the pH increasing during growth of the Fusarium sp. in 1 mM tellurite to ∼pH 6·7 after 2 wk. In contrast, the pH decreased during growth of P. citrinum in 1 mM tellurite, to a level of ∼pH 2·7 after 2 wk. On agar medium, test fungi exhibited tolerance to high levels of tellurite (up to 100 mM Na2TeO3) and this was associated with blackening of the growing colonies as well as the surrounding agar. TEM revealed the deposition of large black granules, apparently in vacuoles, which corresponded with the reduction of tellurite to amorphous elemental tellurium. Precipitation of amorphous tellurium on and around the biomass was also observed and confirmed by energy-dispersive X-ray microprobe analysis. In addition to the reductive transformation of tellurite, Fusarium sp. also displayed transformation of tellurite into a volatile form. The production of volatile tellurium by Fusarium sp. occurred over the whole growth period and amounted to an average value of 7·8 μmol Te (∼0·16%) from 51 growth medium with an initial concentration of 1 mM Na2TeO3. Although P. citrinum also transformed tellurite to elemental tellurium, volatilization of tellurium was not detected. It is concluded that different mechanisms of tellurium transformation are species-dependent and can be influenced by physico-chemical changes in the medium, e.g. pH, which can affect tellurium speciation into soluble and insoluble forms and bioaccumulation. In view of the extremely small amounts of Te volatilized by the Fusarium sp., this process cannot be considered to be an important detoxification mechanism.

Healthy-looking needles were randomly collected from Pinus mugo ssp. uncinata at two sites in the montane zone with different edaphic and microclimatic conditions and examined for the diversity of endophytic fungi. One site is on a mountain ridge, the other in a peat bog. On average, about 35–40% of the needles were colonized at both sites. Eleven species of fungi were isolated. Cenangium ferruginosum and Cyclaneusma minus dominated the endophytic mycobiota of the tree stand along the mountain ridge. C. ferruginosum and Lophodermium pinastri were the dominant species in the needles of the trees in the peat bog. C. ferruginosum and L. pinastri occurred mainly in the needle tip; C. minus occurred most frequently in the middle segment of the needles. The needle base was rarely colonized by these fungi. Endophyte colonization of trees along the mountain ridge increased significantly from the uppermost trees to the ones further down the ridge. No clear pattern of colonization was observed for trees in the peat bog except for the colonisation by L. pinastri, which showed a tendency to form infection centres. Species composition was constant within sites, but the frequency of colonization by C. minus and L. pinastri varied greatly among trees.

Confocal laser scanning microscopy was used for in vivo observations of autofluorescent fungal structures of Glomus mosseae in intact, living rye-grass roots. Clear images of hyphae and collapsed arbuscules could be obtained without staining or sectioning roots. As rye-grass roots are highly transparent, with only a few cell layers above the vascular cylinder, they provide an excellent in vivo system for microscopical confocal laser scanning studies of arbuscular mycorrhizal structures.

A method to identify the earliest stages (initials) of Pleurotus pulmonarius and Coprinus cinereus fruit body formation was developed. Light microscopy and Cryo-SEM were used to confirm that even the smallest structures to take up stain were initials of fruit bodies. An approach combining histological staining (flooding the Petri dish with 1% toluidine blue in 1% boric acid (w/v) for 15 min) and image analysis allowed the number of fruit bodies formed on Petri dishes to be quantified easily. Use of the vital stain Janus green (0·001% aqueous, w/v) allowed continued observation of living tissue so that the proportion of fruit bodies that matured (30%) could be established. The method was also effective on wheat straw cultures and could be used to monitor development of mature fruit bodies. It is a promising tool in the study of physiological processes involved in fruit body initiation.

Thirty-five isolates of Gaeumannomyces graminis were tested for ability to infect wheat, rye and oats, and for DNA polymorphisms using nuclear ribosomal DNA (rDNA) RFLP patterns and RAPD analysis. In general, the cereal-attacking isolates could be readily assigned to the rye-attacking (R) or non-rye-attacking (N) subgroups of var. tritici, or to var. avenae, on the basis of either of these molecular approaches. A small number of isolates gave anomalous rDNA RFLP patterns, but could nevertheless be assigned to one of the three groups by RAPD analysis. Two related G. graminis var. tritici isolates (T1–1 and T1–2) clearly grouped with the N rather than the R var. tritici subgroup on the basis of molecular analysis but were pathogenic to rye, indicating that the ability to infect this host may have arisen more than once. An earlier phylogenetic study of Gaeumannomyces involving DNA sequence analysis of the internal transcribed spacers of the rDNA indicated that several oat-infecting isolates originally classified as G. graminis var. tritici could be grouped with var. avenae isolates. From the rDNA RFLP and RAPD analysis described here, however, these isolates appear to be intermediate between var. avenae and var. tritici, although it is not clear whether they represent evidence of inter-varietal sexual hybridization.

We studied the occurrence of genotypes of Gnomonia setacea by RAPD-PCR analysis at two natural sites in SW Finland to study site-, tree- and leaf-level genetic diversity. The analysis was performed with two primers by using 40 isolates from a total of 250 colonies isolated from two trees from each of two sites. Genetic diversity of G. setacea was found to be very high: every isolate studied was a unique genotype, even within the same leaf. This is probably due to sexual reproduction and the horizontal transmission system of airborne spores. Genotype distribution exhibited site-level similarity, indicating limited spore deposition and the ability to form local populations.

A numerical taxonomic analysis of 272 specimens and strains of Leptoxyphium, Caldariomyces and Aithaloderma was undertaken. Analysis was carried out on two data sets: characters from the form of the hyphal cells, shape of conidiomata and the presence of ascospores were coded and 34 binary variables encoded for all strains; 29 living cultures of Leptoxyphium and Caldariomyces were characterized for colony morphology, micromorphology and physiological characters encoded as 168 binary variables. Cluster analysis, principal components analysis and discriminant analysis was carried out. Three main groups are identified. A group comprising mainly Aithaloderma specimens is most clearly resolved. Another group comprises a mixture of Caldariomyces and Leptoxyphium specimens. The third group comprised mainly Leptoxyphium specimens with some Aithaloderma specimens. Physiological characters provide no evidence for the separate recognition of Caldariomyces and Leptoxyphium.

Ultrastructural and morphological studies have been carried out on M. tumidum, the type species of Myelosperma. Asci are provided with a distinctive refractive subapical ring, which differs from that found in other unitunicate families. The ascospores are reniform in all species and surrounded by mucilaginous sheaths of various shapes. Numerous ascomata also develop in a circle around a common central pore. At the ultrastructural level the ascus apex comprises an electron-transparent thickening incorporating a subapical electron-dense hemispherical ring-like structure and the ascus wall is continuous over the apex. This type of ring is compared with those found in representative species in other related families. Based on these observations, a new family, the Myelospermaceae, is introduced, to accommodate Myelosperma. The rationale behind this is discussed, and M. alata is described to accommodate a remarkable new species from the Seychelles. Arguments for the possible inclusion of Manokwaria, Palmicola and Pemphidium in the Myelospermaceae are given.

We try to explain the large differences observed in the proportion of needles colonized by fungal species in coniferous litter by spore dispersal properties. We constructed a population dynamics model, assuming that litter is a resource that is fragmented into ephemeral units, periodically produced. Spore dispersion on needles on a small spatial scale was assumed to follow a Poisson distribution. The model was compared with an experimental system using Thysanophora penicillioides on Abies alba needles and its relevance to field conditions is discussed.

Experimental systems were established for the molecular analysis of different developmental stages of Glomus mosseae. RNA and DNA were simultaneously extracted from ectocarpic spores, chlamydospores, dormant and germinating sporocarps and extraradical hyphae. A β-tubulin gene fragment was obtained by PCR from spore genomic DNA and further analysed. β-tubulin RNA expression could be monitored during the fungal life cycle with a gene-specific primer by RT–PCR using an internal cRNA standard.

Strains of Heterobasidion annosum belonging to the S and P intersterility groups (IGs) were compared in respect of laccase activity on various substrates. Biomass production was significantly lower in P cultures than in S cultures. By contrast, laccase activity, measured in relation to growth rate, was significantly higher for the P strains tested, compared with a similar number of S strains, particularly in substrates, rich in carbohydrates as well as in inorganic and organic nitrogen. Using the Bradford assay method, P cultures were shown to contain significantly higher amounts of protein than S. The pH optimum of laccase for both IGs was 4·5 with guaiacol as substrate and 5·3 with syringaldazine. Isozyme patterns varied greatly, depending on strain, substrate and incubation time. In P cultures 4–5 bands were obtained, whereas S strain laccase was mostly separated into 2–3 isozyme bands. Only one was significantly different in position between the IGs. The results may help to explain why P strains are more aggressive than S strains as pathogens and wood decayers.

This listing covers the period November 1, 1997 through to December 31, 1997. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees. All correspondence about this item should be addressed to the Executive Editor. Reprints of this feature will not be available.