Interaction structures with host cells and molecular phylogenetic studies of the Dothideomycetes with particular emphasis on (hemi-)biotrophic plant parasites

• Applicant: Dr. Uwe Simon
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 23261458

The Dothideomycetes is a major group of fungi that includes numerous phytopathogenous species and some human and animal pathogens and is crucial for an understanding of the phylogeny of ascomycetous fungi and their life-styles. Despite their economic and scientific importance many taxonomic questions within this group remain unsolved at almost all taxonomic levels from circumscription of orders to species delimitation. In our previous work we have described a complex type of cellular interaction formed by Cymadothea trifolii (sooty blotch of clover), an obligate biotrophic pathogen living in leaves of Trifolium species. Our starting hypothesis for the project applied for is that biotrophism within the Dothideomycetes may be an ancestral character. Furthermore, different modes of cellular interaction might reflect distinct taxonomic relationships, as has been shown for the basidiomycetous smut fungi. Consequently, we want to thoroughly analyse a large number of (hemi-)biotrophic Dothideomycetes for the specific interactions realized with host cells (e.g. intracellular hyphae, haustoria). The questions addressed are, whether certain types of interaction are restricted to specific clades (validated by genetic data), and whether a development from simple to complex structures can be traced back (e.g. intracellular hyphae ¿¿haustoria ¿¿intercellular hyphae with interaction apparatus). This study incorporates electron microscopy and molecular analyses employing a multi-gene approach with four genetic markers (nuSSU rDNA, nuLSU rDNA, RPB 1 + 2). The aim is to test the above hypotheses and to understand the evolution of interactions of fungi with photosynthetic organisms.

• DFG Programme: Research Grants