I study the evolution of fungi involved in the lichen symbiosis. Lichens are intriguing fungal-green algal-cyanobacterial associations, whose evolutionary history and biology are little understood. It is unclear, for instance, why lichenized fungi produce such a great variety of uncommon secondary metabolites, when closely related non-lichenized fungi do not. What could be the functions of these small molecules in the lichen symbiosis? I am interested in using molecular phylogenetics as a tool to study such questions. Basis for the analyses are DNA sequences, morphological, and chemical data. We explore the evolutionary history of morphological and chemical characters by mapping them on molecular trees. We have shown, for example, that basic concepts of fungal classification based on fruiting body morphology, the single most important character in fungal systematics, have to be reviewed, if the evolution of lichenized as well as non-lichenized taxa is considered. Also, we study functionally significant gene families, such as polyketide synthase genes directly. Proteins encoded by these genes are predicted to be involved in the biosynthesis of rare and bioactive molecules produced by lichenized fungi. We are currently analyzing the complex evolutionary history of these genes, which involves duplications and possibly horizontal gene transfer.
Schmitt, I. & Lumbsch, H.T. 2009. Ancient horizontal gene transfer from bacteria enhances biosynthetic capabilities of fungi. PloS ONE 4: e4437.
Schmitt, I., del Prado, Grube, M., Lumbsch, H.T. 2009. Repeated evolution of closed fruiting bodies is linked to ascoma development in the largest group of lichenized fungi (Lecanoromycetes, Ascomycota). Mol. Phylogenet. Evol. 52: 34-44.
Schmitt, I., Partida-Martinez, L.P., Winkler, R., Voigt, K., Einax, E., Dölz, F., Telle, S., Wöstemeyer, J. & Hertweck, C. 2008. Evolution of host resistance in a toxin-producing bacterial–fungal alliance. ISME J 2: 632-641.
Schmitt, I., Kautz, S. & Lumbsch, H.T. 2008. 6-MSAS-like polyketide synthase genes occur in lichenized ascomycetes. Mycol. Res. 112: 289-296.
Muggia, L., Schmitt, I. & Grube, M. 2008. Purifying selection is a prevailing motif in the evolution of ketoacyl synthase domains of polyketide synthases from lichenized fungi. Mycol. Res. 112: 289-296.
Schmitt, I., Yamamoto, Y. & Lumbsch, H.T. 2006. Phylogeny of Pertusariales (Ascomycotina): resurrection of Ochrolechiaceae and new circumscription of Megasporaceae. Hattori Bot. Lab. 100: 753-764.
Schmitt, I., Lumbsch, H.T. & Bratt, C. 2006. Two new brown spored species of Pertusaria from southwestern North America. Lichenologist. 38: 411-416.
Lumbsch, H.T., Schmitt, I., Barker, D. & Pagel, M. 2006. Evolution of micromorphological and chemical characters in the lichen-forming fungal family Pertusariaceae. Biol. J. Linn. Soc. 89: 615-626.
Schmitt, I., Lumbsch, H.T. & Mueller, G. 2005. Ascoma morphology is homoplaseous and phylogenetically misleading in some pyrenocarpous lichens. Mycologia 97: 362-374.
Schmitt, I., Martin, M.P., Kautz, S. & Lumbsch, H.T. 2005. Diversity of non-reducing polyketide synthase genes in the Pertusariales (lichenized Ascomycota): a phylogenetic perspective. Phytochemistry 66: 1241-1253.
Schmitt, I. & Lumbsch, H.T. 2004. Molecular phylogeny of the Pertusariaceae supports secondary chemistry as an important systematic character set in lichen-forming ascomycetes. Mol. Phylogenet. Evol. 33: 43-55.
Schmitt, I., Lumbsch, H.T. & Søchting, U. 2003. Phylogeny of the lichen genus Placopsis (Agyriales) and its allies based on Bayesian analyses of nuclear and mitochondrial sequence data. Mycologia 95: 827-835.