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Splivallo R.,Goethe University Frankfurt | Splivallo R.,Integrative Fungal Research Cluster IPF | Ebeler S.E.,University of California at Davis
Applied Microbiology and Biotechnology | Year: 2015

Truffles are symbiotic fungi in high demand for the aroma of their fruiting bodies which are colonized by a diverse microbial flora. Specific sulfur containing volatiles (thiophene derivatives) characteristic of the white truffle Tuber borchii were recently shown to be derived from the bacterial community inhabiting truffle fruiting bodies. Our aim here was to investigate whether thiophene derivatives contributed to the human-sensed aroma of T. borchii. Furthermore, we questioned whether the concentration of thiophene volatiles was affected by freezing or whether it differed in truffles from distinct geographical origins. Gas chromatography–olfactometry (GC-O) analysis revealed that thiophene derivatives were major contributors to the aroma of T. borchii. Of four thiophene derivatives detected in this study, 3-methyl-4,5-dihydrothiophene was the most important one in terms of its contribution to the overall aroma. The relative concentration of thiophene derivatives was unaffected by freezing; however, it differed in samples collected in distinct geographical locations (Italy versus New Zealand). The causes of this variability might be differences in storage conditions and/or in bacterial community composition of the fruiting bodies; however, further work is needed to confirm these hypotheses. Overall, our results demonstrate that thiophene derivatives are major contributors to the human-sensed aroma of T. borchii. © 2015, Springer-Verlag Berlin Heidelberg.

Thines M.,Integrative Fungal Research Cluster IPF | Thines M.,Biodiversity and Climate Research Center | Thines M.,Goethe University Frankfurt
European Journal of Plant Pathology | Year: 2014

Oomycetes have colonised all continents and oceans in a great variety of habitats and are arguably one of the most successful eukaryotic lineages. This is contrasted by the limited knowledge available for this group in various fields in comparison to other ubiquitous eukaryotes, such as unikont fungi, animals or plants. In this review an overview is given on the evolution and diversification of the oomycetes, with focus on the plant parasitic lineages and aspects of wild pathosystems. © 2014 KNPV.

Molinier V.,Swiss Federal Institute of forest | Molinier V.,CNRS Agroecology Lab | Murat C.,University of Lorraine | Murat C.,French National Institute for Agricultural Research | And 4 more authors.
Environmental Microbiology | Year: 2015

Truffles are symbiotic fungi in high demand by food connoisseurs. Improving yield and product quality requires a better understanding of truffle genetics and aroma biosynthesis. One aim here was to investigate the diversity and fine-scale spatial genetic structure of the Burgundy truffle Tuber aestivum. The second aim was to assess how genetic structuring along with fruiting body maturation and geographical origin influenced single constituents of truffle aroma. A total of 39 Burgundy truffles collected in two orchards were characterized in terms of aroma profile (SPME-GC/MS) and genotype (microsatellites). A moderate genetic differentiation was observed between the populations of the two orchards. An important seasonal and spatial genetic structuring was detected. Within one orchard, individuals belonging to the same genet were generally collected during a single season and in the close vicinity from each other. Maximum genet size nevertheless ranged from 46 to 92m. Geographical origin or maturity only had minor effects on aroma profiles but genetic structuring, specifically clonal identity, had a pronounced influence on the concentrations of C8- and C4-VOCs. Our results highlight a high seasonal genetic turnover and indicate that the aroma of Burgundy truffle is influenced by the identity of single clones/genets. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Choi Y.-J.,Goethe University Frankfurt | Choi Y.-J.,Biodiversity and Climate Research Center | Thines M.,Goethe University Frankfurt | Thines M.,Biodiversity and Climate Research Center | Thines M.,Integrative Fungal Research Cluster IPF
PLoS ONE | Year: 2015

Even though the microevolution of plant hosts and pathogens has been intensely studied, knowledge regarding macro-evolutionary patterns is limited. Having the highest species diversity and host-specificity among Oomycetes, downy mildews are a useful a model for investigating long-term host-pathogen coevolution. We show that phylogenies of Bremia and Asteraceae are significantly congruent. The accepted hypothesis is that pathogens have diverged contemporarily with their hosts. But maximum clade age estimation and sequence divergence comparison reveal that congruence is not due to long-term coevolution but rather due to host-shift driven speciation (pseudo-cospeciation). This pattern results from parasite radiation in related hosts, long after radiation and speciation of the hosts. As large host shifts free pathogens from hosts with effector triggered immunity subsequent radiation and diversification in related hosts with similar innate immunity may follow, resulting in a pattern mimicking true co-divergence, which is probably limited to the terminal nodes in many pathogen groups. © 2015 Choi, Thines. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Choi Y.-J.,Goethe University Frankfurt | Choi Y.-J.,Biodiversity and Climate Research Center | Klosterman S.J.,U.S. Department of Agriculture | Kummer V.,University of Potsdam | And 6 more authors.
Molecular Phylogenetics and Evolution | Year: 2015

Accurate species determination of plant pathogens is a prerequisite for their control and quarantine, and further for assessing their potential threat to crops. The family Peronosporaceae (Straminipila; Oomycota) consists of obligate biotrophic pathogens that cause downy mildew disease on angiosperms, including a large number of cultivated plants. In the largest downy mildew genus Peronospora, a phylogenetically complex clade includes the economically important downy mildew pathogens of spinach and beet, as well as the type species of the genus Peronospora. To resolve this complex clade at the species level and to infer evolutionary relationships among them, we used multi-locus phylogenetic analysis and species tree estimation. Both approaches discriminated all nine currently accepted species and revealed four previously unrecognized lineages, which are specific to a host genus or species. This is in line with a narrow species concept, i.e. that a downy mildew species is associated with only a particular host plant genus or species. Instead of applying the dubious name Peronospora farinosa, which has been proposed for formal rejection, our results provide strong evidence that Peronospora schachtii is an independent species from lineages on Atriplex and apparently occurs exclusively on Beta vulgaris. The members of the clade investigated, the Peronospora rumicis clade, associate with three different host plant families, Amaranthaceae, Caryophyllaceae, and Polygonaceae, suggesting that they may have speciated following at least two recent inter-family host shifts, rather than contemporary cospeciation with the host plants. © 2015 Elsevier Inc.

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