Phylogenetic diversity of endophytic Pestalotiopsis species in Pinus armandii and Ribes spp.: evidence from rDNA and β- tubulin gene phylogenies

Abstract

The diversity of endophytes associated with bark and needles of Pinus armandii and leaves of Ribes species was investigated and resulted in 132 isolates being identified as Pestalotiopsis species. Isolates were grouped into morphospecies based on morphology and cultural characteristics and named based on morphological characters. To supplement identifications, ribosomal DNA (ITS and 5.8S) and β-tubulin gene sequences from 37 isolates representing diverse morphological and cultural characteristics were analyzed phylogenetically (maximum parsimony and Bayesian criteria). Phylogenies corroborated with morphologies and are largely congruent with previously established taxonomic schemes. Phylogenetic comparison of the two genes reveals that ITS based phylogenies alone were not suitable to infer phylogenetic relationships among Pestalotiopsis species as most of the clades did not receive adequate statistical support, β-tubulin phylogenies were better resolved but a combined dataset was found to be more appropriate. Although results are generally concordant with published studies, there seems to be several inconsistencies in grouping taxa at the species level. The phylogenetic relationships of species in relation to culture morphology, as well as to host and tissue association are discussed.