Paleogene Radiation of a Plant Pathogenic Mushroom

Background: The global movement and speciation of fungal plant pathogens is important, especially because of the economic losses they cause and the ease with which they are able to spread across large areas. Understanding the biogeography and origin of these plant pathogens can provide insights regarding their dispersal and current day distribution. We tested the hypothesis of a Gondwanan origin of the plant pathogenic mushroom genus Armillaria and the currently accepted premise that vicariance accounts for the extant distribution of the species. Methods: The phylogeny of a selection of Armillaria species was reconstructed based on Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI). A timeline was then placed on the divergence of lineages using a Bayesian relaxed molecular clock approach. Results: Phylogenetic analyses of sequenced data for three combined nuclear regions provided strong support for three major geographically defined clades: Holarctic, South American-Australasian and African. Molecular dating placed the initial radiation of the genus at 54 million years ago within the Early Paleogene, postdating the tectonic break-up of Gondwana. Conclusions: The distribution of extant Armillaria species is the result of ancient long-distance dispersal rather than vicariance due to continental drift. As these finding are contrary to most prior vicariance hypotheses for fungi, our result

Airborne fungal spore monitoring: between analyst proficiency testing

This study presents the results of a Europe-wide training and Quality Control (QC) exercise carried out within the framework of the European Aerobiology Society’s QC Working Group. The main aim of this exercise was to examine the feasibility of carrying out a QC exercise for fungal spore monitoring in Europe, using a similar methodology to the one previously used for pollen. The QC survey was conducted in two parts: (1) Coordinators of national and regional aerobiological networks in Europe involved in the monitoring of atmospheric fungal spores were invited to complete a questionnaire survey related to their network and asked whether they were interested in taking part in an external inter-laboratory QC exercise; (2) Participating networks performed an inter-laboratory ring test with the same sample slide in order to determine the reproducibility of identifying and counting two fungal spore taxa (Alternaria and Epicoccum) in air samples collected by a Hirst-type volumetric spore trap. Participants were instructed to read five separate longitudinal transects in the “effective collecting area” of the slide. Reproducibility of analysis was determined following the method previously used in the European Aerobiology Society’s QC exercises for pollen. Thirty-two counters from 16 national or regional networks in Europe participated in the QC exercise. Coefficients of Variation (CV%) ranged from 23.0 to 22.5 when reading one transect and from 14.0 to 16.0 when reading five transects for Alternaria and Epicoccum, respectively. Considering a CV% of 30 as the limit for fungal spores, no significant differences were observed between the absolute errors from two, three, four and five transects. The only significant difference was between one and five transects. We recommend that fungal spore analysis should be carried out on about 5% of the slide (two transects in this study) because results were not significantly different to five transects