Mycology

The aim of this study was to apply a generated Δtku70 strain with increased homologous recombination efficiency from the mycoparasitic fungus Trichoderma virens for studying the involvement of laccases in the degradation of sclerotia of plant pathogenic fungi. Inactivation of the non-homologous end-joining pathway has become a successful tool in filamentous fungi to overcome poor targeting efficiencies for genetic engineering. Here, we applied this principle to the biocontrol fungus T. virens, strain I10, by deleting its tku70 gene. This strain was subsequently used to delete the laccase gene lcc1, which we found to be expressed after interaction of T. virens with sclerotia of the plant pathogenic fungi Botrytis cinerea and Sclerotinia sclerotiorum. Lcc1 was strongly upregulated at early colonization of B. cinerea sclerotia and steadily induced during colonization of S. sclerotiorum sclerotia. The Δtku70Δlcc1 mutant was altered in its ability to degrade the sclerotia of B. cinerea and S. sclerotiorum. Interestingly, while the decaying ability for B. cinerea sclerotia was significantly decreased, that to degrade S. sclerotiorum sclerotia was even enhanced, suggesting the operation of different mechanisms in the mycoparasitism of these two types of sclerotia by the laccase LCC1.

An ascomycete with non stromatic, narrowly ovoidal or subpyriform, pale yellow to luteous perithecia, a Nectria-like centrum, yellowish-brown reticulate ascospores, and a Trichothecium-like anamorph has been isolated from small rodent dung in Italy. Based on morphological, cultural and molecular (nrLSU and ITS sequences) data, a new genus, Rodentomyces, and a new species, R. reticulatus, are therefore introduced to accommodate this fungus. Rodentomyces represents a hypocrealean genus in the Nectriaceae. Within this family, and based on molecular data, R. reticulatus is placed in the group including Calonectria, Leuconectria, Nectricladiella, Neonectria and Nectria mariannaeae. Several coprophilous genera are recorded in Hypocreales almost evenly distributed among the main families of this order.

The genus Diaporthe comprises pathogenic, endophytic and saprobic species with both temperate and tropical distributions. Cryptic diversification, phenotypic plasticity and extensive host associations have long complicated accurate identifications of species in this genus. The delimitation of the generic type species Diaporthe eres has been uncertain due to the lack of ex-type cultures. Species limits of D. eres and closely related species were evaluated using molecular phylogenetic analysis of eight genes including nuclear ribosomal internal transcribed spacer (ITS), partial sequences of actin (ACT), DNA-lyase (Apn2), translation elongation factor 1- α (EF1-α), beta-tubulin (TUB), calmodulin (CAL), 60s ribosomal protein L37 (FG1093) and histone-3 (HIS). The occurrence of sequence heterogeneity of ITS within D. eres is observed, which complicates the analysis and may lead to overestimation of the species diversity. The strict criteria of Genealogical Concordance Phylogenetic Species Recognition (GCPSR) were applied to resolve species boundaries based on individual and combined analyses of other seven genes except the ITS. We accept nine distinct phylogenetic species including Diaporthe alleghaniensis, D. alnea, D. bicincta, D. celastrina, D. eres, D. helicis, D. neilliae, D. pulla and D. vaccinii. Epitypes are designated for D. alnea, D. bicincta, D. celastrina, D. eres, D. helicis and D. pulla. Modern descriptions and illustrations are provided for these species. Newly designed primers are introduced to amplify and sequence the Apn2 (DNA- lyase) gene in Diaporthe. Based on phylogenetic informativeness profiles, EF1-α, Apn2 and HIS genes are recognised as the best markers for defining species in the D. eres complex.

Mycorrhizal symbioses are an important link in the chain of response of ecosystems to global changes especially as they promote plant phosphorus uptake and act as a sink for plant carbon and alleviate photosynthetic down-regulation. Because hyphal turnover is likely to be fast, especially in warmer soils, they can also act as a rapid pathway for the return of carbon to the atmosphere. As with other major below-ground components of terrestrial ecosystems, the response of the ubiquitous mycorrhizal fungal root symbionts to GEC has received limited attention. Most of the research on the effects of GEC on mycorrhizal fungi has been pot-based with a few field (especially monoculture) studies. A major question that arises from all these studies is whether the GEC effects on the mycorrhizal fungi are independent of the effects on their plant hosts. This is important because in natural ecosystems, it is thought that GEC effects on mycorrhizal fungal communities is greatly influenced by the effects on plant communities to the extent that community level interactions will prove to be the key mechanism for determining GEC-induced changes in mycorrhizal fungal communities.
This paper looks at the effects of global environmental changes on mycorrhizal fungi via traits such as hyphal turn over, running speed, hyphal length and how these changes may affect ecosystem functions, such as nutrient and carbon cycling.

Keywords: Elevated CO2, temperature, mycorrhizal function, diversity, moisture, traits, P- phosphorus, N-nitrogen, sequestration, deposition, nutrient cycling, global environmental change.

The first report of Scytinopogon from Mexico is presented. Descriptions of Mexican material of S. pallescens and S. robustus are included, and the nomenclature of the described species is discussed along with the systematic and phylogenetic affinities of the genus.

The phylogenetic relationships of Ramariopsis and related taxa were studied through a cladistic analysis of 36 morphological, cytological, and biochemical characters among 23 species in six genera. Two of these genera were directly studied as groups of interest, three as external taxonomic outgroups, and one as operative outgroup. Representatives of Ramariopsis sensu Corner formed a monophyletic group, supported by the cyanophilous nature of their basidiospores and derivation of their ornamentation from the tunica. The new combination, Clavulinopsis antillarum, is proposed.