Abstract:
Species of Leptographium sensu lato (Ophiostomatales, Ascomycetes) are sap-stain fungi
vectored by bark beetles (Coleoptera, Scolytinae) and some species cause or are associated
with tree diseases. Sexual states have been reported for more than 30 species in this group and
these have been treated in the sexual genus Grosmannia. No sexual state is known for at least
59 additional species and these reside in the genus Leptographium. The discovery of sexual
states for species of Leptographium relies mainly on the presence of fruiting bodies on host
tissue at the time of isolation and/or intensive laboratory mating studies, which commonly
have a low levels of success. In this study, markers were developed to diagnose mating-type
and to study sexual compatibility of species in Leptographium sensu lato using these markers.
To achieve this objective, available mating type sequences for species of Leptographium
sensu lato and Ophiostoma were obtained, aligned and used to design primers to amplify
MAT genes in Grosmannia and Leptographium species. Using these primers, it was possible
to amplify portions of the mating type genes for 42 species and to determine thallism, in many
species for the first time. Surprisingly, the results showed that heterothallic and putatively
heterothallic species are abundant (39 out of 42 species) in Leptographium sensu lato, and
only three species were confirmed to be homothallic. The mating-type markers developed in
this study will be useful for future studies concerning mating type and sexual compatibility of
species in this genus.
