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Abstract Detail


Joukhajian, Arik [1], Arnold, A. Elizabeth [2], Glassman, Sydney [1].

Foliar endophytic fungi diverge from forest-scale island biogeography patterns observed in Yosemite ectomycorrhizae.

Microbial community diversity can adhere to the principles of island biogeography, such that diversity correlates with island size and age, and isolation restricts immigration. By modelling systems in this context, we can better understand drivers of ecological diversity at multiple scales. Prior studies show that ectomycorrhizal fungi, which form mutualistic associations with tree roots, adhere to island biogeography principles when trees that are isolated from a forest edge are treated as islands. Foliar endophytic fungi are symbiotic inhabitants of leaves, but whether they similarly reflect island biogeography principles at tree- and leaf scales is not known. We used Illumina MiSeq sequencing of the internal transcribed spacer (ITS1) region to examine foliar endophytic fungal communities in healthy needles of isolated pine trees (Pinus albicaulis, P. contorta) in a subalpine basin in Yosemite National Park. In parallel we used Sanger sequencing to identify endophytic fungi isolated in culture. We evaluated variation in endophyte diversity and community structure as a function of tree size, tree age, and needle age for each tree species, and characterized the taxonomy of endophytes in this relatively extreme environment for isolated trees. The richness of endophytic fungi per tree was low relative to that of pines sampled with similar methods in other environments, with a median of 9 species per individual. However, high variation in richness was observed in Pinus albicaulis, with some individuals harboring more than four times that median richness. As a whole, the community was species-rich, with more than 270 putative species occurring in foliage of these isolated trees. Illumina sequencing and culturing approaches were complementary, with one family unique to cultures and 64 families unique to Illumina MiSeq. Overall the dominant class was Dothideomycetes (Ascomycota), represented primarily by the endophyte-rich order Capnodiales. Richness was significantly higher in older needles in P. albicaulis, but not in P. contorta. Unlike ectomycorrhizal fungi in the same trees, foliar endophyte richness was not correlated strongly with tree age or tree size. We concluded that foliar endophytic fungi do not adhere simply to the island biogeography model with respect to the tree as a whole, perhaps reflecting their airborne dispersal. They merit further study at a finer spatial scale to determine the ecological processes shaping their communities.

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1 - University of California, Riverside, Microbiology and Plant Pathology, 900 University Ave, Riverside, CA, 92521, USA
2 - School Of Plant Sciences, 2327 E 7th St, Tucson, AZ, 85719, United States

foliar fungal endophyte
island biogeography
Fungal diversity

Presentation Type: Poster
Session: MYP3, Mycology Posters III
Location: /
Date: Wednesday, July 21st, 2021
Time: 5:00 PM(EDT)
Number: MYP3011
Abstract ID:1083
Candidate for Awards:MSA Best Poster Presentation Award by a Graduate Student

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