Hoff, J.A. et al. Fungal endophytes in woody roots of Douglas-fir (pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa).xxxxxxxxxxxxxxxxxxxxxxxxxxxx

The objective of this study was to establish baseline information on latent fungal pathogens and endophytes associated with large woody roots of apparently healthy Douglas-fir and ponderosa pine. Increment cores were collected from trees growing in dry forests on the eastern slope of the Cascade Mountains in Washington.

Fungal isolates were cultured on standard media, and then were identified using a combination of molecular and morphological methods. The molecular methods involved examination of internal transcribed spacer (ITS1 and ITS2) and 5.8S rDNA sequences.

· Fungi were isolated from nearly half of the 289 root cores from symptomless ponderosa pine and Douglas-fir. Approximately 52% of the cores did not yield fungi, 38% yielded growth of one fungal genus, and 9% yielded multiple fungal genera. A wide diversity of fungi was recovered from root cores in this study, comprising 3 phyla, 11 orders, 13 families and 27 genera.

· Host species and plant association did not significantly influence the proportion of cores from which fungi were recovered or the recovery of individual fungal species.

· Byssochlamys nivea and Umbelopsis species were the most frequently recovered fungi. This is the first report of these fungi within large woody roots of conifers. Both taxa have been previously identified as potential biological control agents.

· Byssochlamys nivea was identified using both DNA sequencing and morphological characteristics. B. nivea is a potential biological control species, known to inhibit in vitro growth of some plant pathogenic fungi and cause death in certain nematodes. B. nivea is also known to be heat resistant. Considering its heat tolerance, biological control potential, and widespread occurrence, B. nivea may have significant interactions with forest fungal pathogens.

· The Umbelopsis isolates could only be identified to the genus level at this time. Umbelopsis species are found in forest ecosystems around the world. There are many unanswered questions concerning Umbelopsis species and their interaction with other forest organisms.