First report of Myrothecium roridum from a gymnosperm. North American Fungi

Abstract

Although Myrothecium roridum has been reported as a pathogen and an endophyte with a wide host range among Angiosperms, it has never before been reported from a gymnosperm host. Reports of this fungus are also much more common in Asia than in North America where M. roridum is infrequently found on introduced plants in the warmer, southernmost parts of the United States. Thus, it was surprising on three levels to isolate endophytic M. roridum from a North American native gymnosperm, Pinus albicaulis , at high elevation in Crater Lake National Park (CLNP) in Oregon. In PDA culture, its olive green conidia were 6-8 µm long (mean of 6.8) × 2 µm wide, and cylindrical with rounded ends. Conidia formed dark green to black masses on sessile sporodochia in concentric zones. The sequence identity of the ITS1, ITS2 and the 5.8S rRNA of CLNP isolate RV10#75 (GenBank accession GQ152603) with deposited sequences of M. roridum in the National Center for Biotechnology Information database was 99.82%. The conservation implications of this finding are discussed.