Morphological Characterization of Fungal Endophyte Community Structure in Leaf Tissue of Quercus rubra

Endophytic fungi occur in healthy tissues of plants, playing potentially important roles in the ecology and evolution of their hosts.We examined endophytic fungi in both asymptomatic and infected foliage of red oak (Quercus rubra) at Bard College, Annandale-On-Hudson, NY. In order to to evaluate morphotaxa, visual groupings and BLAST matches of sequence similarity were conducted. We used these methods to estimate endophyte diversity and species composition by investigating the relationships between leaf health and endophyte community structure. Using traditional ecological indices, I estimated endophyte diversity and spatial heterogeneity across two ecologically similar locations on the Bard campus. Foliar endophytes were recovered in culture from 89.58% of sampled leaf hole punches, yielding a total of 960 isolates that represented 131 distinct morphotypes. 84 rare morphotypes were recovered only once, whereas all other morphotypes were recovered from multiple leaves across locations. Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) of the most prevalent morphotype confirmed reliability of morhpotypic groupings.This morphotype mapped to Sordariomycetes sp. genotype 483, a foliar endophyte isolated from Quercus montana. Endophytes morphological diversity did not differ in composition at either leaf or tree level indicating that the communities may be structured based on location. These preliminary results require a larger-scale, molecular characterization of these morphotypes before coming to a conclusion about endophyte host colonization preferences