Phylogeny of Penicillium and the segregation of Trichocomaceae into three families

Species of Trichocomaceae occur commonly and are important to both industry and medicine. They are associated with food spoilage and mycotoxin production and can occur in the indoor environment, causing health hazards by the formation of β-glucans, mycotoxins and surface proteins. Some species are opportunistic pathogens, while others are exploited in biotechnology for the production of enzymes, antibiotics and other products. Penicillium belongs phylogenetically to Trichocomaceae and more than 250 species are currently accepted in this genus. In this study, we investigated the relationship of Penicillium to other genera of Trichocomaceae and studied in detail the phylogeny of the genus itself. In order to study these relationships, partial RPB1, RPB2 (RNA polymerase II genes), Tsr1 (putative ribosome biogenesis protein) and Cct8 (putative chaperonin complex component TCP-1) gene sequences were obtained. The Trichocomaceae are divided in three separate families: Aspergillaceae, Thermoascaceae and Trichocomaceae. The Aspergillaceae are characterised by the formation flask-shaped or cylindrical phialides, asci produced inside cleistothecia or surrounded by Hülle cells and mainly ascospores with a furrow or slit, while the Trichocomaceae are defined by the formation of lanceolate phialides, asci borne within a tuft or layer of loose hyphae and ascospores lacking a slit. Thermoascus and Paecilomyces, both members of Thermoascaceae, also form ascospores lacking a furrow or slit, but are differentiated from Trichocomaceae by the production of asci from croziers and their thermotolerant or thermophilic nature. Phylogenetic analysis shows that Penicillium is polyphyletic. The genus is re-defined and a monophyletic genus for both anamorphs and teleomorphs is created (Penicillium sensu stricto). The genera Thysanophora, Eupenicillium, Chromocleista, Hemicarpenteles and Torulomyces belong in Penicillium s. str. and new combinations for the species belonging to these genera are proposed. Analysis of Penicillium below genus rank revealed the presence of 25 clades. A new classification system including both anamorph and teleomorph species is proposed and these 25 clades are treated here as sections. An overview of species belonging to each section is presented

Community profiling and gene expression of fungal assimilatory nitrate reductases in agricultural soil

Although fungi contribute significantly to the microbial biomass in terrestrial ecosystems, little is known about their contribution to biogeochemical nitrogen cycles. Agricultural soils usually contain comparably high amounts of inorganic nitrogen, mainly in the form of nitrate. Many studies focused on bacterial and archaeal turnover of nitrate by nitrification, denitrification and assimilation, whereas the fungal role remained largely neglected. To enable research on the fungal contribution to the biogeochemical nitrogen cycle tools for monitoring the presence and expression of fungal assimilatory nitrate reductase genes were developed. To the ∼100 currently available fungal full-length gene sequences, another 109 partial sequences were added by amplification from individual culture isolates, representing all major orders occurring in agricultural soils. The extended database led to the discovery of new horizontal gene transfer events within the fungal kingdom. The newly developed PCR primers were used to study gene pools and gene expression of fungal nitrate reductases in agricultural soils. The availability of the extended database allowed affiliation of many sequences to known species, genera or families. Energy supply by a carbon source seems to be the major regulator of nitrate reductase gene expression for fungi in agricultural soils, which is in good agreement with the high energy demand of complete reduction of nitrate to ammonium

A technique for obtaining monokaryotic haploid hyphae of Ustilago tritici, causal agent of wheat loose smut

Twenty isolates of Ustilago tritici [U. segetum var. tritici] were collected from various parts of northern India and used for monokaryotic haplont production. Teliospores from the infected wheat samples were surface sterilized and 150-250 mul of sterilized teliospore suspension was evenly spread on Petri dishes containing 1.5-2 mm thick, 1.5% water agar and DL-aspartic acid (0.147 mg/ml water). The Petri dishes were incubated at 20℃ for about 30 hours. Dikaryon formation was observed and subsequently 1 cm2 blocks of medium from these plates were transferred to plates of 1/5 normal nutrient concentration of potato dextrose agar and incubated in the refrigerator overnight. The squares were then transferred to another layer of 1/5 PDA pre-warmed to25?and kept at this temperature for 4-6 hours. Monokaryotic haploid hyphae were obtained and isolated by microsurgery with very thin Pasteur pipettes and transferred to a thick layer of 1/5 PDA and kept at 20? Growth of haplonts was relatively slow and was visible only after 4-5 days. After 2 weeks, the verrucose colonies of fungus which were dense, cream to pinkish cream, could be seen. The mycelial mass production of the mycelium of haploid hyphae can be obtained by inoculation of potato sucrose broth in shaker incubation at 130 rpm, 20?for 14-20 days. This technique was effective in obtaining monokaryotic haploid hyphae for all 20 isolates of U. segetum var. tritici