Mycological Research News features: Checks and balances in endophyte-host interactions; In this issue; TrichoBLAST: a multilocus database for Trichoderma and Hypocrea identifications; Did pathogenic fungi contribute to dinosaur extinction?; and Forthcoming international mycological meetings.

This part starts with a major review of the nature of endophytic associations involving fungi, and includes eight other research papers. These describe a new genus associated with ambrosia beetles, characterise Scutellospora reticulata, analyse a chaperone homologue gene in Paracoccidiodes brasiliensis, examine growth responses of soil chytrids, revise the hyphomycete genus Piricauda, assess the status and relationships of Agaricus mushrooms in sect. Duploannulati, report decreasing effectiveness of prochloraz-manganese to control Verticillium fungicola over time, and examine the mineral contents (including metal ions) in Amanita fruit bodies.

The following new scientific names are introduced: Dryadomyces gen. nov.; D. amasae, and Piricauda vulcanensis spp. nov.; and Acrodictys caribensis (syn. P. caribensis) comb. nov.

In spite of the term ‘endophyte’ being employed for all organisms that inhabit plants, mycologists have come to use the term ‘fungal endophyte’ for fungi that inhabit plants without causing visible disease symptoms. The term refers only to fungi at the moment of detection without regard for the future status of the interaction. This paper is a review of literature on non-balansiaceous fungi involved in asymptomatic colonisations of plants. These fungal endophytes represent a continuum of fungi with respect to physiological status, infection modus, colonisation pattern, secondary metabolism, life-history strategy, and developmental and evolutionary stages, but also with respect to the fungal and host taxa involved in the symbioses.

We hypothesize that there are no neutral interactions, but rather that endophyte-host interactions involve a balance of antagonisms, irrespective of the plant organ infected. There is always at least a degree of virulence on the part of the fungus enabling infection, whereas defence of the plant host limits development of fungal invaders and disease. It is also hypothesized that the endophytes, in contrast to known pathogens, generally have far greater phenotypic plasticity and thus more options than pathogens: infection, local but also extensive colonisation, latency, virulence, pathogenity and (or) saprophytism. This phenotypic plasticity is a motor of evolution.

During surveys of woodlands in Taiwan a previously undescribed fungus Dryadomyces amasae gen. sp. nov., was found in the sapwood of dead angiosperm timbers in the gallery systems of the scolytine ambrosia beetle Amasa concitatus. The fungus grows predominantly in the immediate vicinity of the feeding beetle larvae and serves as a nutritional ambrosia fungus. The transmission of D. amasae to new breeding substrates is ensured by an oral mycetangium, a paired organ which was found in A. concitatus and A. aff. glaber near the mandibles and contained multiple cells of the fungus. Morphologically D. amasae resembles species of Ambrosiella. However, phylogenetic analysis based on partial nucSSU rDNA placed the fungus with certain species of the genus Ambrosiella within the Ophiostomatales, whereas the type species of Ambrosiella, A. xylebori, was assigned to the Microascales. A. xylebori, as well as A. ferruginea and A. hartigii, demonstrated phialidic conidial development, leading to an emendation of the description of the genus Ambrosiella. In contrast, Dryadomyces exhibited conidial development by apical, sympodial wall formation with prominent denticles bearing conidia. Other, previously described Ambrosiella species exhibited non-phialidic conidiogenesis, but lacked denticles on the conidiophores. Consequently, their classification needs further revision.

The arbuscular mycorrhizal (AM) fungus Scutellospora reticulata (CNPAB11) was characterized using morphological, ontogenetic and molecular approaches. Spore ontogenesis was studied using Ri T-DNA transformed carrot roots and observations were compared with those published for eight other, pot-cultured, Scutellospora species. The sporogenesis of S. reticulata exhibited an unreported pattern of outer spore wall differentiation. In addition, Denaturing Gradient Gel Electrophoresis (DGGE), targeting the V9 region of the SSU nrDNA, was used to differentiate S. reticulata from 16 other Scutellospora species and results were confirmed by sequencing analysis. Phylogenetic analyses, using nearly full length SSU nrDNA sequences, grouped S. reticulata in a cluster together with S. cerradensis and S. heterogama, species that share similar spore wall organization and also possess ornamented external walls. PCR-DGGE and sequence analysis revealed intragenomic SSU nrDNA polymorphisms in four out of six Scutellospora species tested, and demonstrated that SSU nrDNA intragenomic polymorphism could be used as a marker to differentiate several closely related Scutellospora species.

A cDNA encoding a chaperone ClpA homologue of Paracoccidioides brasiliensis was isolated and characterized. The ClpA belongs to a group of ClpATPAses proteins, which are highly conserved, and include several heat inducible molecular chaperones. In this study, a 2879 bp cDNA designated as Pbclpa was obtained which encodes a predicted protein of 927 amino acids. Characteristic consensus motifs of the ClpATPases family are present. The PbClpA middle region was compared to other related ClpA and ClpB proteins from fungi and bacteria. Comparative analysis demonstrated in the middle region the presence of a heptad repeat sequence, characteristic of ClpBs from prokaryotes and fungi, which are absent in ClpAs from prokaryotes but were present in all described fungal ClpAs. Our comparative analysis reveals that one of the criteria typically used to distinguish the prokaryotic subfamilies ClpA and ClpB, the size of the middle sequence, may not be useful in fungi. Phylogenetic analyses were performed with the complete sequences of ClpAs from fungi and bacteria and with the middle regions of those ClpAs present at NCBI and Pfam databases. Our results indicated that both types of analysis can be useful as a tool in the determination of phylogenetic relationships.

Chytridiomycota were isolated into pure culture from cool temperate and warm semi-arid soils of eastern Australia. In pure culture these fungi responded variably to the range of temperatures commonly recorded in their environment. All members of the Blastocladiales, Spizellomycetales and Chytridiales grew in culture at temperatures up to 30 °C. Some isolates from the Blastocladiales and Spizellomycetales continued to grow at or above 37 °. Some isolates of the Chytridiales grew up to but not beyond 35 °. All isolates in the Chytridiales were able to resume growth at 20 ° after brief exposure to temperatures higher than the maximum growth temperature, but were killed by exposure to higher temperatures for 7 d. Because in the natural soil habitat temperature may exceed the maximum for growth it may be a limiting factor that determines the distribution of chytrids in the soil.

The genus Piricauda comprises eight species characterized by monotretic conidiogenous cells and micronematous arched conidiophores: P. cochinensis, P. cubensis, P. longispora, P. mexicana, P. paraguayensis, P. pseudarthriae, P. taiwanensis, and P. vulcanensis sp. nov. P. caribensis is transferred to Acrodictys. Species usually colonize dead petioles and rachides of palms in tropical and subtropical areas, but can also be found on branches and leaves of different trees. The species are illustrated and briefly described, and a key to them is provided.

The position of several endemic and rare species in Agaricus sect. Duploannulati and the limits of the section were investigated by analysis of sequence data from the ribosomal DNA ITS. The results supported the recognition of two groups, which we treat as subsections Chitonioides and Duploannulati. Most of the species studied proved to belong to subsect. Chitonioides. Species excluded from the section, as well as other potential members of sect. Duploannulati, are considered. Morphological traits deemed important for identification of A. nevoi, A. pequinii, A. gennadii, A. rollanii, and A. padanus are discussed. Taxonomic positions of these species in morphologically-based systems and according to molecular systematics data are compared and analyzed.

105 isolates of Verticillium fungicola from Spanish mushroom crops collected between 1992 and 1999 were tested in vitro for their sensitivities to prochloraz-manganese. Dose response relationships for inhibition of mycelial growth by the fungicide were assessed in radial growth experiments on fungicide-amended malt extract agar. The ED50 values recorded for all 105 isolates studied ranged between 0.8 ppm in 1992 and 8.8 in 1998, with an average of 2.9. 86% of the isolates tested were more sensitive to prochloraz-manganese and had ED50 values below 5 ppm, while the other 14% were slightly tolerant with ED50 values equal or above 5 ppm. Of those tested from 1999, 60% (21 isolates) grew with 50 ppm and 40% (14) also at 100 ppm, although mycelial growth was inhibited at least by 82 and 87%, respectively. The resistance factor calculated ranged from low fungicide resistance (RF=3.0) in 1992 to moderate resistance (RF=12.6) in 1998. These data confirm that the sensitivity of V. fungicola to the prochloraz-manganese gradually diminishes.

Basidiomes of 43 samples of eight Amanita species were gathered from different habitats of Hungary. The mineral composition (22 elements) was analysed by the ICP method in three independent replications, and mineral compositions found as discussed and compared. The Amanita species analysed were very different in As-, Cd-, Cr-, Mo-, Mn-, Se- and mainly in V-content. Other elements (Al, B, Ba, Ca, Co, Cu, Fe, Mg, Na, Ni, Sr, Ti, Zn) occur in the basidiomes in balanced concentrations. The K and P contents have the lowest differences. Summarizing all the data (n=43), the average mineral status of species of Amanita can be deduced. The lowest variability measured was for K and P, and the highest for chromium, nickel and vanadium.

Specific, significant accumulation was found only for vanadium, due to the previously demonstrated occurrence of a binding molecule ‘amavadine’ in the basidiomes of A. muscaria. Remarkable Cd-levels were estimated in A. pantherina and A. muscaria (11.4 and 12.3 mg kg−1D.M., respectively). The higher contents of other elements (e.g. K, practically in all species; Se in A. strobiliformis) are analytical facts but, not accumulations.

The mineral compositions of the ectomycorrhizal genus Amanita, of litter decomposing Agaricus and of wood decaying Trametes were compared. Some significant differences were found (AsAmanita<AsAgaricus; CdAmanita<CdAgaricus; CuAmanita<CuAgaricus; PAmanita<PAgaricus; KAmanita>KTrametes; PAmanita>PTrametes) but it seems that the mineral composition of the basidiomes is practically independent of the ectomycorrhizal habit. The specificities of the fungi-tree symbiotic interactions are known, and well documented (higher uptake and transport of certain elements first of all of P), however, the differences found in the mineral components are due to other factors (e.g. substrates, accumulating ability) and not to the mycorrhizal status.