Organelle genomes of lichens

The organelle genomes of three lichen species (P. membranacea, P. malacea and C. grayi; photobiont Asterochloris sp) were sequenced, annotated and comparated to its closest non-lichenized counterparts. These organisms are of interest as they serve as models for studying symbiosis. They are difficult to culture these in the laboratory. The mycobiont mitochondrial genomes are approximately 50-60 kb in size, circular molecules containing genes coding for 14 proteins along with one ribosomal protein (rps3), two rRNA genes and a set of 26 tRNA genes. In addition the Peltigera mtDNAs code for plasmid origin DNA polymerase (dpoB) type B2 and rnpB, encoding the RNA component of RNaseP. Mitochondrial sequences of Peltigera spp. and C. grayi are the first reported from Lecanoromycetes. The phylogenetic tree of concatenated mitochondrial proteins from the lichenized fungi and other ascomycetes exhibits a pattern significantly different from those derived from nuclear proteins. The Asterochloris sp mitochondrial and chloroplast genomes are amongst the largest organelle genomes in green algae. The mitochondrial genome of Asterochloris sp is of the conventional type, it contains a canonical arrangement of a single large rRNA gene along with a 5S rRNA gene, encodes almost a almost full set of tRNAs and has remanants of Group II introns. The chloroplast genome of Asterochloris sp is lacking cysA, encoding a generally onserved transport protein and its tilS (tRNA-Ile lysidine synthase) gene is split, unlike in its chloroplast relatives. Asterochloris sp is the first species to be sequenced from a lichen photobiont of the order Microthamniales belonging to the class Trebouxiophyceae. These organelle genomes will serve as tools to study the function, and evolution of these lichens and its photobionts and the evolutionary cycle of their associated Group I and II introns.Rannsóknasjóður ÍslandsInniheldur efni sum mun birtast í vísindatímaritum, m.a. hugverk annarra aðila