Development of new molecular markers for phylogeny and molecular identification of arbuscular mycorrhizal fungi (glomeromycota)

The RPB1 gene was analyzed as a possible new nuclear-encoded molecular marker for the Glomeromycota. New Glomus group A-specific primers were designed and successfully tested on several members of this group. No evidence for genetic variability was found within the isolates. Based on the new RPB1 sequences, phylogenetic analyses were performed. The phylum-level phylogeny of the fungi was very well resolved by protein sequence analyses. The Glomeromycota were recovered as a monophyletic group, with the Mortierellales (Zygomycota) as closest relatives. A symbiomycotan clade (Asco-, Basidio and Glomeromycota) was not supported in the RPB1 phylogeny whereas the "Dicaryomycota" (Asco- and Basidiomycota) were supported in the trees. The morphospecies-level RPB1 phylogeny of Glomus group A performed best using nucleotide sequences. Interestingly, Geosiphon pyriformis was determined to be the most deeply-diverging lineage of the Glomeromycota. However, RPB1 sequences of representatives of the remaining families are needed for for a comprehensive phylogeny of glomeromycotan fungi. All members of the Glomeromycota contained an intron at the same location in their RPB1 gene. This sequence region seems to be ideal for molecular species identification using restriction analysis in community studies of the AMF in the future.