One of the most fascinating result of our work on smut fungi is the high degree of host specialisation in most of the smut groups. Many monophyletic parasitic lineages infect members of a single monophyletic host group. For several groups, we have proven that this observation is not a distribution by chance but instead a result of association by descent. Unfortunately, detailed data are not available for the majority of smut species at this time. Hence, we started to compare host and parasite phylogenies.
Microbotryum betonicae on Stachys alopecuros
Our work on cophylogeny concentrates on the genus Microbotryum. Since several species of the genus sporulate in the anthers of their hosts, it seems that insects are important vectors. However, we are interested in the evolution of the whole genus Microbotryum , which infects a great range of dicot families, of which some have been colonised twice. We are additionally studying the specificity of Microbotryum on the population genetics level using infection studies . Therefore we established living cultures of several species of Caryophyllaceae and started to study the phylogeny of Saponaria and Dianthus as well. In the long term we are interested in the comparison of ecologically similar but convergent systems of plant parasitism.
Poaceae are used as a model group for the study of their interaction with smut fungi. The pathogen Ustilago maydis and its relatives are of economical relevance as they parasitize cereals. In addition, the smuts can be genetically modified which makes them useful for an integrative study of the evolution of the parasitic interaction. Ronny Kellner works on the evolution of mating genes and fungal effectors in this group of fungi and their role in speciation. At the moment we are extending the analysis to more genes, which are known to be important in the interaction.
Interested in the evolution of ecosystems, I am also working on the biodiversity of yeasts in phyllosphere and soil in the framework of the DFG-Exploratories Programme (long-term biodiversity study sites). Together with colleagues in Halle (Francois Buscot) and Göttingen (Rolf Daniel) we are trying to establish metagenomic studies to explore the unknown diversity of these fungal groups. The implementation of this technique will be a milestone in the biodiversity assessment of microorganisms, because it will allow the inclusion of fungi in large ecological surveys on a micro scale. Recently, Andrey Yurkov got an additional grant from the DFG to study the seasonal dynamics of soil yeasts in the exploratories, which will allow us, to establish quantitative PCR as a method to study abundance of soil yeasts and other fungi.