Comparative genomic analysis of five lichen-forming fungi 
H. SONG (1), K. Kim (2), J. Jeon (1), S. Park (3), J. Hur (3), Y. Lee (2) (1) Interdiscplinary Program in Agricultural Genomics, Seoul National University, Seoul 151-921, Korea, Korea; (2) Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea, Korea; (3) Korean Lichen Research Institute, Sunchon National University, Suncheon, South Korea, Korea

Lichen-forming fungi associated with green algae or cyanobacteria are known as mutualists. These fungi maintain symbiotic relationship by providing nutrient ions and receiving photosynthetic products from their partners. Lichens synthesize a great number of secondary metabolites, which bestow important biological activities. In order to reveal these important biological properties of lichens, several genomes of lichen-forming fungi have been published. To better understand the unique characteristics of lichen-forming fungi, we performed comparative analysis with genomes of five lichen-forming fungi (Caloplaca flavorubescens, Cladonia macilenta, C. metacorallifera, Umbilicaria muehlenbergii and Endocarpon pusillum) with 38 fungal and oomycete species. The phylogenomic analysis shows that these lichen-forming fungi are paraphyletic, because the first four species belong to Lecanoromycetes and E. pusillum belongs to Eurotiomycetes. We identified three MCL clusters specific to lichen-forming fungi and the most genes in these clusters were highly expressed in C. flavorubescens at 1 week after resynthesized with its algal partner. It was also evident that polyketide synthase genes were evolutionally duplicated in the lichen clades, but lower numbers of secreted proteins were detected in comparison to other fungal species. These results shows that some gene families were evolutionarily expanded, gained or lost in lichen-forming fungi. These evidences further imply that lichens may have different symbiosis system compared to other symbiotic fungi such as mycorrhizae. This bioinformatics analysis will help us to better understand the unique genomic characteristics of lichen-forming fungi and will provide new insights on molecular nature of fungal symbiosis. 

Abstract Number: P2-50
Session Type: Poster