Genetic stability of ectomycorrhizal fungi is not affected by cryopreservation at -130 °C or cold storage with repeated sub-cultivations over a period of 2 years.

Cryopreservation is considered the most reliable method for storage of filamentous fungi including ectomycorrhizal (ECM) fungi. A number of studies, however, have reported genetic changes in fungus cultures following cryopreservation. In the present study, the genetic stability of six ECM fungus isolates was analyzed using amplified fragment length polymorphism (AFLP). The isolates were preserved for 2 years either by cryopreservation (at -130 °C) or by storage at 4 °C with regular sub-cultivation. A third preservation treatment consisting of isolates maintained on Petri dishes at 22-23 °C for 2 years (i.e., without any sub-cultivation) was included and used as a control. The differences observed in AFLP patterns between the three preservation methods remained within the range of the total error generated by the AFLP procedure (6.85%). Therefore, cryopreservation at -130 °C and cold storage with regular sub-cultivation did not affect the genetic stability of the ECM fungus isolates, and both methods can be used for the routine storage of ECM fungus isolates over a period of 2 years.

Starmerella neotropicalis f. a., sp. nov., a yeast species found in bees and pollen.

A novel yeast species was found repeatedly and in high cell densities in underground-nesting stingless bees of the species Melipona quinquefasciata and their provisions in northern Minas Gerais (Brazil). One additional strain was isolated from bee-collected pollen in Cuba. Phylogenetic analyses based on rRNA gene sequences (D1/D2 large subunit gene and internal transcribed spacer) indicated that the novel species belongs to the Starmerella clade and is most closely related to Candida (iter. nom. Starmerella) apicola. Growth reactions on carbon and nitrogen sources were typical of those observed in related species of the Starmerella clade. PCR-fingerprinting with mini- and microsatellite specific primers allowed the distinction of the novel species from Candida apicola, Candida bombi and a yet undescribed species represented by strain CBS 4353. On the basis of phylogenetic relationships, the novel species is assigned to the genus Starmerella despite the failure to observe sexual reproduction after extensive mating tests. We propose the name Starmerella neotropicalis f. a., sp. nov. (Mycobank MB 804285) and designate UFMG PST 09(T) ( = MUCL 53320(T) = CBS 12811(T)) as the type strain.

Wickerhamomyces anomalus in the sourdough microbial ecosystem.

We previously found that Wickerhamomyces anomalus (formerly Hansenula anomala, Pichia anomala) was the second most frequently isolated yeast in Belgian artisan bakery sourdoughs and that the yeast dominated laboratory sourdough fermentations. Such findings are of interest in terms of the advantage of W. anomalus over other commonly encountered sourdough yeasts and its potential introduction into the sourdough ecosystem. Here, we provide a brief overview of current knowledge on yeast ecology and diversity in sourdough in the context of the potential natural habitat of W. anomalus. Insight into the population structure of W. anomalus was obtained by comparing internal transcribed spacer rDNA sequences of selected sourdough isolates with publicly available database sequences.

Anamorphic fungi from French Guyana: two undescribed Gliocephalotrichum species (Nectriaceae, Hypocreales).

Morphological and molecular studies of Gliocephalotrichum collections from rain forest leaf litter in French Guyana revealed the occurrence of two undescribed species, described here as G. bacillisporum and G. longibrachium. Both species have a whorl of sterile stipe extensions directly subtending the conidiogenous penicilli. Gliocephalotrichum bulbilium also was isolated from leaf litter in French Guyana. Two sequences in GenBank, of uncultured ascomycetes from Gabon, Africa, cluster in the Gliocephalotrichum clade, suggesting the probable existence of additional undescribed taxa from the Central African rainforest.

Understanding Puccinia striiformis West. epidemics on winter wheat.

Yellow rust epidemics, caused by Puccinia striiformis West., often arise in wheat field as infection focus of a few decimetres of diameter, including some sporulating lesions on a few plants. Under appropriate environmental conditions such as high relative humidity and temperatures between 2 and 20 degrees C, those initial foci may grow rapidly and initiate new foci elsewhere in the field. The first aim of this work was to better understand the effects of weather parameters on the focus growth. An experiment was conducted in a wheat field during the 2001 season to measure, from inoculated plants, the disease progression related to climatic conditions (temperature, relative humidity, precipitations and wind). Three plots were inoculated in March and the sporulating lesions around each focus were monitored every week on 8 segments starting from the centre of the plot, by recording the infected leaf layers and the spatial position of every infected plant. Once established, the disease spread not only horizontally, by spore transport from plants to plants, but also vertically, by spore dispersal from lower leaf layers to upper ones. The focus required a build up period, with diseased plants confined to a circle of maximum 3 m diameter around the centre with the inoculated plants, before a widespread expansion. This initial build up period required at least two generations. On base of the changes of the disease status observed every week and the calculation of the latent period, the supposed infection dates and the environmental factors responsible for those infections were determined. This allowed adjustment of an infection forecasting model based on weather data. These results will be integrated into a decision support system to control the disease before the occurrence of large scale inoculum dispersion.