Morphological and Molecular Diagnosis of Leptographium spp. in Canadian Softwoods
S Alamouti, Jae-Jin Kim, A Uzunovic, C Breuil
Sapstaining fungi that affect commercially important softwood species mainly belong to the genera Ceratocystis, Ophiostoma and Leptographium. Our 1997-1999 fungal surveys confirmed that this is the case in Canada. The work reported here addresses identifying the morphologically plastic Leptographium at the species level, which is difficult using conventional methods. We assessed the morphological and physiological characteristic of survey isolates grown on artificial media and wood, and then compared them with reference cultures. The morphological data obtained from isolates grown on wood were less variable and, therefore, more conclusive, than those grown on artificial media. Microscopic observation of isolates grown on wood, differentiated them into three known Leptographium groups: aureum, clavigerum, and abietinum. Preliminary DNA sequence data for the ITS2 rDNA and β-tubulin genes confirmed the identity of the three species, but also indicated two additional groups. Ongoing biological work and sequencing of other genes will clarify the relationships between these species and discrepancies between morphological and molecular data.