XVI International Botanical Congess

80-90% of vascular plants form an endomycorrhizal symbiosis with the obligate symbiotic arbuscular mycorrhiza fungi (AMF), improving plant nutrition. AMF have been placed into the order Glomales. Despite their importance, evolution and phylogeny of AMF has yet to be understood. Geosiphon pyriforme, a unique coenocytic fungus forming an endosymbiosis with cyanobacteria, belongs to the Glomales. This opens interesting views regarding the evolution of AM symbiosis. SSU rRNA genes of glomalean species were analyzed to obtain more information about glomalean phylogeny, evolution, and the phylogenetic position of Geosiphon. Topics discussed are:- which information Geosiphon gives about evolution of AM and land plants?- are Glomales monophyletic or is the AM symbiosis a result of convergent evolution?- are AMF Zygomycetes, or related to other fungi?