PS 19-27
Endophyte community development in Pinus monticola
Fungal endophytes occur in all conifer forest systems and the formation of endophyte community begins very early within the individual host lifecycle. This makes it difficult to monitor early endophyte community formation and development. Conifer seedlings grown under greenhouse conditions have limited fungal colonization, as decreased exposure to environmental propagules inhibits infection. Seedlings transplanted from the greenhouse into forested ecosystems provide a unique opportunity to explore the initial formation of these fungal communities. Changes in the community composition since time of planting provide insight into how endophytes compete within their communities and how communities develop over time. Newly developed high-throughput sequencing technology allows us to more efficiently characterize microbial communities. We developed methods to amplify fungal DNA directly from pine needles and used Illumina sequencing technology to explore fungal species richness, diversity, and community composition in needle tissue of 61 Western white pines (Pinus monticola), propagated in greenhouse conditions and then transplanted into the forest after two years.
Results/Conclusions
Fungal infection of needle tissue at time of planting was less than 1%, providing an open template for colonization by endophytes present in the surrounding forest ecosystem. After 6 months, we collected approximately 5000 needles from 61 trees. Sequencing of the internal transcribed spacer 2 (ITS2) region averaged more than 1000 reads per tree and detected more than 6000 distinct molecular OTUs, at 97% similarity. This far exceeds any previously uncovered OTU richness in a single Western white pine forest community to date. Fungi in the phylum, Ascomycota, represented 72.6% of all non-singleton OTUs, while Basidiomycota represented 13.2%. Remaining OTUs were unidentified at the phylum level. The most abundant species belonged to the genus, Sydowea, and occured in all trees sampled. This is consistent with previous culture-based studies of the same population. Trees with highly abundant OTUs tended to have less diversity than trees containing lower abundance OTUs.