Nomenclatural and identification pitfalls of endophytic mycota based on DNA sequence analyses of ribosomal and protein genes phylogenetic markers: A taxonomic dead end?

Fungal endophytes are considered ecologically important microorganisms, but their role is the subject of much speculation and the methods and approaches by which endophytes are detected and identified give rather different results. In this study, we isolated a specific endophyte from a traditional medicinal plant and investigated its phylogenetic relationships with other known fungi. Microscopic examination and cultural details of the strain are documented, but these did not provide adequate data to substantially identify the species, either to a genus or species level. To overcome this limitation, six different gene regions (SSU, LSU, ITS, TEF, RBP2 & beta-Tubulin) were amplified, sequenced and analysed phylogenetically (either in individual or concatenated datasets) to identify and investigate the placement of this endophyte at different taxonomic ranks. Results obtained from the cultural morphology were insufficient to identify the species. DNA sequence analyses (either single gene or combined gene analyses) revealed that this endophyte belongs to the order Pleosporales, class Dothideomycetes. However, an accurate establishment of its generic or even familial position is unresolved and the problems associated with our current system of assigning endophytes to a particular rank are discussed.