This number of Mycological Research News features: In this issue; Centenary of a mycologist: C. Terence Ingold; Terence Ingold reflects; Assembling the fungal tree of life (AFTOL); and Limestone as a source of unidentifiable melanized fungi.

The 11 research papers in this issue consider: the genetic basis of autolysis in Aspergillus nidulans; the life-cycle of Cymadothea trifolii; interaction of the mycoparasite Pythium oligandrum with sclerotia; effects of flavonoids on AM-fungal growth; the influence of AM-fungi on growth in Coleus forskohlii; molecular detection of Eutypa lata; genetic variation in Pyrenophora teres; discovery of an Aschersonia teleomorph; a new basidiomycete genus from mangroves; a new conidial nectriaceous genus from Celtis; and a reconsideration of Pseudoperonospora cubensis and P. humuli.

The following new scientific names are introduced in this part: Dematiocladium and Haloaleurodiscus gens. nov.; D. celtidis, H. mangrovei, and Hypocrella zhongdongii spp. nov.

The fluG gene proved to be essential in the initialisation of autolysis in Aspergillus nidulans (teleomorph Emericella nidulans) cultures, while a loss-of-function mutation in only one out of the flbB-E genes had only minor effects on autolysis. In contrast to its important role in sporulation, brlA regulated only some, but not all, elements of the autolytic process. The tightly coupled autolytic events (chitinase and proteinase production, hyphal fragmentation, disorganisation of pellets, autolytic loss of biomass) observable in ageing cultures of A. nidulans were disconnected by loss-of-function mutations in some genes of the FluG-BrlA regulatory network. The tight correlation between pellet morphology and size and hydrolase production was also erased by these mutations. On the other hand, the mutations studied did not affect the glutathione metabolism of the fungus.

The vegetative life-cycle of Cymadothea trifolii (anamorph Polythrincium trifolii), causing sooty blotch of clover, is described using chemically as well as cryofixed and freeze-substituted samples. The pathogen enters the leaf through stomata and proliferates intercellularly. Nutrients are assumedly obtained via an interaction apparatus produced within the pathogen's hyphae, opposite to which the host cell is triggered to invaginate its plasmalemma. Rare attempts of ‘self-parasitism’ were also seen. Entering the conidial stage, stromata are laid down under the lower epidermis. The dying tissue above may explain the necrotic spots observed on infected leaflets. Foot cells in the conidial stromata produce thick-walled conidiophores, which grow sympodially. New conidiophores may grow into empty shells of old ones. Conidia are detached after pores between them and conidiophores have become plugged by organelles resembling Woronin bodies. Conidia are usually two-celled and their walls contain chitin and β-1,3-glucans as indicated by labelling with gold-conjugated wheat germ agglutinin and anti-β-1,3-glucan antibodies. Both conidiophores and conidia contain a structure which we regard as a new organelle with as yet unknown function.

The interactions between Pythium oligandrum hyphae and two types of sclerotia, i.e. the plano-convexoid sclerotium of Botrytis cinerea and the tuberoid sclerotium of Sclerotinia minor, were investigated by ultrastructural and cytochemical experiments. In the mycoparasitism of P. oligandrum, some differences in relation to sclerotium anatomy and the role of the rind layer in preventing invasion are documented. Both types of sclerotia showed neither alterations of the heavily melanised rind walls, nor direct rind wall penetration by P. oligandrum. This oomycete successfully entered B. cinerea sclerotia only through breaches at the junction of rind cells and corresponding to gaps in melanin deposits. On the other hand, none of these breaches was observed in the small sclerotia of S. minor, and P. oligandrum ingress in the sclerotia stopped at the inner rind layer. After the penetration of B. cinerea sclerotia by the mycoparasite, it extensively colonised the cortical and medulla areas by intercellular growth. The invaded tissues displayed pronounced alterations as well as some disorganisation of tissue in places. Colonisation was associated with severe chitin degradations of all host walls, which occurred even at some distance from P. oligandrum hyphae. The observation of wall thickenings in some P. oligandrum–hyphae suggests that the sclerotial cells constitute a harsh environment unsuitable for survival of the mycoparasite. These wall thickenings could be interpreted as P. oligandrum defence-like reactions.

The effect of the flavonoids chrysin, isorhamnetin, kaempferol, luteolin, morin and rutin on pre-symbiotic growth, such as spore germination, hyphal length, hyphal branching and the formation of auxiliary cells and secondary spores, of the arbuscular mycorrhizal fungi Gigaspora rosea, G. margarita, Glomus mosseae and G. intraradices was studied. According to the effect on each fungal growth parameter, the tested compounds could be classified to be genus and/or species specific or specific, for a certain developmental stage of pre-symbiotic growth. A clear arbuscular mycorrhizal genus specific, and even species specific, effect of some flavonoids was observed. However, this specificity of a flavonoid could not be generalized but differs depending on the pre-symbiotic stage of the AM fungus. Moreover, our show that for a better understanding of the role of compounds in the AM symbiosis, studies should not be conducted only with one AM fungus looking at one fungal growth parameter such as spore germination or hyphal length, but should be wider, including several growth parameters and several AM fungi.

A glasshouse investigation was conducted to study the effectiveness of 11 arbuscular mycorrhizal (AM) fungi on the medicinal plant Coleus forskohlii. Coleus plants raised in presence of most of the AM fungi in polythene bags showed an increase in plant growth (height, number of branches and biomass), P, and forskolin contents over those grown in the absence of soil inoculation with AM fungi. The extent of growth, P, and forskolin status varied with the AM fungi used. Based on the plant biomass, P uptake and forskolin content per plant, Glomus bagyarajii was found to be the best AM symbiont for inoculating C. forskohlii, the next being Scutellospora calospora.

Eutypa lata, the causal agent of Eutypa dieback of grapevines, is difficult to identify on the basis of colony morphology and is often out-competed by other fungi when isolated from wood. To facilitate diagnosis of the pathogen, we designed SCAR primers capable of amplifying DNA of E. lata and constructed a genomic DNA library from which DNA sequences specific to E. lata were identified and sequenced. SCAR primers were used to identify E. lata directly from culture without the requirement for DNA extraction or prolonged incubation periods and could also detect the pathogen in DNA isolated from grapevine wood. RFLP probes were used in slot-blot assays to detect the pathogen in DNA isolated from 1 yr old cane as well as from mature grapevine trunks. The markers developed in this study have the potential to be used as a research tool to gather information on the epidemiology of the disease and to assess the efficacy of potential control agents against E. lata.

The amplified fragment length polymorphism (AFLP) was used to study genetic variation in Pyrenophora teres causing net blotch of barley in Finland. The mean similarity was 93% between all isolates and a bit higher within two distinct populations based on 175 AFLP markers. Despite the high genetic similarity, 70 unique AFLP genotypes were identified among 72 isolates. Most of the genetic variation (68.5%) was observed within a field population and a smaller portion (30.3%) between them. Significant genetic differentiation (Fst=0.308, P<0.001) was identified between field populations. However only 1.2% of the variation was observed between mating types within a field and a lack of genetic differentiation (Fsc=0.017, P=0.087) was observed. The occurrence of the form of blotch (spot type, f. sp. maculata, or net type, P. teres f. sp. teres) was identified with specific PCR. All isolates were found to be of the net type. The existence of both mating types (MAT1 and MAT2) was identified for the first time in Finland and the ratio of the two mating types was almost 1[ratio ]1 in both locations. The evolutionary potential and the possibility of sexual reproduction of P. teres occurring in Finland are discussed.

A new Hypocrella species with white pulvinate stromata collected in Puerto Rico and Costa Rica is described as H. zhongdongii sp. nov. Morphological and molecular evidence confirms that the new species of Hypocrella is the teleomorph of Aschersonia incrassata. It most closely resembles H. andropogonis; both A. incrassata and A. andropogonis are common yellow-spored species. The relationships of H. zhongdongii with other species in the genus are elucidated through phylogenetic analyses of three different genetic loci (LSU, RPB2, and mtSSU). Our analysis also sheds light on current subgeneric concepts in Aschersonia, in which the presence or absence of conidiomatal paraphyses is a major character to separate the genus into two subgenera. The present phylogenetic tree suggests that paraphyses have been lost or gained multiple times during evolutionary history, and do not define monophyletic groups.

Haloaleurodiscus gen. nov. (Homobasidiomycetes) is described from Japanese mangrove forests with one species H. mangrovei sp. nov. The genus is morphologically characterized by having resupinate basidioma, nodose-septate hyphae, sulphoaldehyde-positive gloeocystidia, dendrohyphidia and amyloid basidiospores with minute warts. These morphological features are similar to those of Aleurodiscuss. lat., but H. mangrovei differs from the Aleurodiscus primarily in occurring in white pocket-rot and is not closely related based on ribosomal DNA sequence analyses. Molecular data suggest that this species is phylogenetically placed in the root of the ‘Peniophorales’ clade. In addition, ecological and physiological features of the species are provided.

A Cylindrocladium-like hyphomycete collected on leaf litter of Celtis tala in Argentina had rDNA sequence data (ITS and LSU) that showed it resides in the Hypocreales, and is a member of the Nectriaceae, closely related to, but distinct from Cylindrocladium. A new genus, Dematiocladium and species, D. celtidis gen. sp. nov. is, therefore, introduced to accommodate this fungus. Based on morphology, it can be distinguished from other conidial hypocrealean genera with hyaline, penicillate conidiophores and cylindrical conidia by lacking stipe extensions and vesicles, and by the presence of brown to dark brown, thick-walled setae.

Phylogenetic analysis of the ITS rDNA region was carried out with two economically important downy mildews, Pseudoperonospora cubensis, which infects species of Cucumis, Cucurbita, and Citrullus belonging to Cucurbitaceae, and P. humuli, which infects plants of the genus Humulus belonging to Cannabaceae. Two closely related species, P. cannabina and P. celtidis, were also included to reveal taxonomic relationships with the first two mildews. All four species formed a well-resolved clade when compared with the ITS sequences of other downy mildew genera, using Bayesian inference and maximum parsimony. The P. cubensis isolates obtained from different hosts and (or) geographical origins in Korea, exhibited no intraspecific variability in the ITS sequences. The phylogenetic analyses of P. cubensis and P. humuli showed that they share a high level of sequence homology; the morphology of the sporangiophores, sporangia, and dehiscence apparatus confirmed the similarity of the two species. We therefore reduce P. humuli to the status of a taxonomic synonym of P. cubensis.