XVI International Botanical Congess

Fungi of the lichen genus Cladonia form symbiotic associations with green algae of the genus Trebouxia. We amplified the nuclear rDNA ITS region of phycobionts associated with Cladonia species from three continents, including T.erici cultured from Cladonia cristatella. Sequence similarity between these phycobionts and the cultured T.erici were comparable to those reported within Trebouxia species, but significantly higher than those between species of Trebouxia. These high similarities were unexpected since the phycobionts were from different continents and from multiple species of Cladonia. This is especially true since rDNA ITS sequences are known vary even within populations. These results have exciting implications for the study of selectivity and specificity in lichen symbiosis, in that different fungi may share a single highly-adapted algal genotype.