Molecular chemotaxonomy of Daldinia and other Xylariaceae

Abstract

In a polyphasic classification approach, stromata and cultures of Daldinia and allied Xylariaceae from around the world were studied for: (1) morphology of teleomorphs and anamorphs; (2) metabolite patterns in stromata and cultures, employing analytical HPLC-UV-visible (diode array) detection and mass spectrometric detection; (3) amplified 18S rDNA restriction patterns (ARDRA); and (4) PCR amplified minisatellite regions. Comparison of type material, herbarium specimens, cultures, and freshly collected material revealed new evidence on their geographic distribution. Several Daldinia spp. were identified in Europe and other locations for the first time. The results point towards the existence of further undescribed species. Stromata of a given species never contained the same major metabolites as corresponding cultures. Most cultures of Daldinia spp. produced naphthalene and chromane derivatives, differing from allied genera by the absence of mellein. Stromata of Daldinia spp. did not produce mitorubrin, but generally contained binaphthyls. Metabolite profiles were correlated with colours of KOH-extractable stromatal pigments. The yellow azaphilones and benzophenones found in D. childiae were lacking in species with purple stromatal pigments. Cytochalasins were found in stromata of D. eschscholzii. Genetic fingerprints helped to distinguish morphologically closely related taxa. ARDRA gave specific results for species whose 18S rDNA contained insertions, while minisatellite PCR provided specific genetic fingerprints. A combination of both PCR based techniques provided a fair resolution of genetic subtypes, reflecting the intrageneric variance in Daldinia as established from morphological data and secondary metabolite profiles.