Coenzyme Q systems in ascomycetous black yeasts

72 Strains belonging to 44 species of ascomycetous black yeasts were analyzed for their coenzyme Q systems. Prevalent were Q-10 and dihydrogenated Q-10 systems. Members of the Dothidealean suborder Dothideineae have Q-10 (H₂), while those belonging to the suborder Pseudosphaeriineae mostly have Q-10. The anamorph genus Exophiala Carmichael and the teleomorph genus Capronia Sacc. seem to be heterogenous.     

SSU rDNA sequence support for a close relationship between the elaphomycetales and the Eurotiales and Onygenales

Based on parsimony analyses of eight new SSU rDNA sequences and 24 homologous sequences retrieved from the DNA databases, we suggest a possible phylogenetic relationship of Elaphomycetales with Eurotiales and Onygenales. Our three includedElaphomyces sequences strongly cluster together (bootstrap value 100%) within a monophyletic group (100%) of Elaphomycetales, Eurotiales, and Onygenales. Earlier reports that another cleistothecial lineage (Erysiphe) is related to Leotiales, are supported by our discovery that also another cleistothecial species,Amylocarpus encephaloides, shows affinity to Leotiales. Ascosphaeraceae and Eremascaceae are possibly better accommodated in Onygenales. We describe a new DNA extraction method in which sonication is used to disrupt thick-walled spores. It is useful for both fresh and dried fungal material.     

Taxonomic studies on new or critical fungi of non-pathogenic Onygenales 1

From recent isolates of microfungi on soil materials collected at several localities in the world, five new taxa of the Onygenales are described and illustrated. A new monotypic genus,Kraurogymnocarpa lenticulospora, is proposed. New species are described inAmauroascus, Aphanoascus, andArachnomyces. A new variety ofPseudogymnoascus roseus is also proposed.     

Prevalent weeds collected from cucurbit fields in Northeastern Brazil reveal new species diversity in the genus Monosporascus

Fungal species belonging to the ascomycete genus Monosporascus have no known asexual morph and the ascocarp is a globose perithecium where asci develop, containing from 1 to 6 spherical ascospores, depending on the species. Monosporascus cannonballus is the most well‐known species of the genus, and an important root pathogen associated with the vine decline of melon and watermelon crops worldwide. The aim of the present study was to characterise a collection of 35 Monosporascus‐like isolates recovered from roots of two weed species prevalent in cucurbit growing fields in Northeastern Brazil: Boerhavia diffusa and Trianthema portulacastrum. These isolates were identified based on DNA sequences of the Internal Transcribed Spacer regions (ITS) of the nuclear rDNA, part of the translation elongation factor gene (tef‐1α), part of the β‐tubulin gene (tub), part of the nuclear small subunit (SSU) rDNA and part of the large subunit (LSU) rDNA. Five Monosporascus species, namely Monosporascus brasiliensis, Monosporascus caatinguensis, Monosporascus mossoroensis, Monosporascus nordestinus and Monosporascus semiaridus, are newly described. Monosporascus brasiliensis, M. nordestinus and M. semiaridus were isolated from both weed species, while M. caatinguensis only from T. portulacastrum and M. mossoroensis only from B. diffusa. The present study confirms that Monosporascus spp. can colonise roots of very diverse hosts, even without causing noticeable disease symptoms, and reveals that the diversity of species in the genus Monosporascus is potentially greater than previously expected.     

Evidence of mycoparasitism and hypermycoparasitism in Early Cretaceous amber

Evidence of mycoparasitism and hypermycoparasitism is demonstrated in Early Cretaceous Burmese amber. The agaric, Palaeoagaracites antiquus gen. sp. nov., is parasitized by the mycoparasite, Mycetophagites atrebora gen. sp. nov., which in turn is parasitized by the hyperparasite, Entropezites patricii gen. sp. nov. This discovery shows that sophisticated patterns of fungal parasitism were well developed some 100 Myrago.     

Size and longevity of seed banks of alpine gentian (Gentiana nivalis L.)

Summary

The alpine gentian (Gentiana nivalis L.) is a mountain rarity found at only two localities in Britain. It is an annual, establishing anew from seed each year and so the size and persistence of its seed bank is important for survival. Seed bank size was measured in summer, before seeds were shed, by sampling from soils at two sites where the alpine gentian is common. As the seeds do not germinate readily in the laboratory, it was assumed that all apparently healthy seeds extracted from the soils were alive and viable. This assumption was corroborated when 95–97% of seeds buried experimentally for 9–12 years germinated after repeated applications of gibberellic acid solution over a period of 6 months.

Densities of naturally buried alpine gentian seeds at the two sites ranged from 1.3 to 6.8 × 10³ seeds m^-2 and they comprised a major component of the community seed bank, disproportionately greater than the abundance of parent plants in the vegetation. The half-life of experimentally buried seeds was estimated as 15 or 32 years, depending on depth of burial and soil type. The findings explain why alpine gentian numbers can recover quickly after a population crash and emphasise the importance of the seed bank to the species' long-term survival in the montane environment.     

To self or not to self? Absence of mate choice despite costly outcrossing in the fungus Podospora anserina

Fungi have a large potential for flexibility in their mode of sexual reproduction, resulting in mating systems ranging from haploid selfing to outcrossing. However, we know little about which mating strategies are used in nature, and why, even in well-studied model organisms. Here, we explored the fitness consequences of alternative mating strategies in the ascomycete fungus Podospora anserina. We measured and compared fitness proxies of nine genotypes in either diploid selfing or outcrossing events, over two generations, and with or without environmental stress. We showed that fitness was consistently lower in outcrossing events, irrespective of the environment. The cost of outcrossing was partly attributed to non-self recognition genes with pleiotropic effects on fertility. We then predicted that when presented with options to either self or outcross, individuals would perform mate choice in favour of the reproductive strategy that yields higher fitness. Contrary to our prediction, individuals did not seem to avoid outcrossing when a choice was offered, in spite of the fitness cost incurred. Our results suggest that, although functionally diploid, P. anserina does not benefit from outcrossing in most cases. We outline different explanations for the apparent lack of mate choice in face of high fitness costs associated with outcrossing, including a new perspective on the pleiotropic effect of non-self recognition genes.     

Multicellular Ascomycetous Fungal Genomes Contain More Than 8000 Genes

Fungi comprise a large monophyletic group of uni- and multicellular eukaryotic organisms in which many species are of economic or medical importance. Fungal genomes are variable in size (13–42 Mb), and multicellular species support true spatial and temporal cell-type-specific regulation of gene expression. In a 38.8-kbAspergillus nidulanscontiguous genomic DNA region, a transposable element and 12 potential genes were identified, 7 similar to genes in other organisms. This observation is consistent with the prediction that multicellular ascomycetous fungi harbor 8000–9000 genes in a 36-Mb average genome. Thus, the genomic DNA sequence of filamentous fungi will provide substantial amounts of genetic and functional information that is not available in yeast, for the human and other metazoan minimal gene complement.