First report of fungal endophyte communities and non-defensive phytochemistry of biocontrol-inoculated whitebark pine seedlings in a restoration planting

Plant-associated
endophyte communities influence plant health and vary with host plant genetics.
Evidence suggests that microfungi of plant interiors (i.e. endophytes) vary
with host genetics due to genetic variation in plant defense phytochemistry. We
examined correlations between fungal endophyte communities, the application of
an endophytic fungal inoculum, and non-defensive phytochemistry of six-year-old
seedlings of whitebark pine (Pinus albicaulis) in a field trial using a
culture-free approach. Fungal communities in whitebark pine foliage were
investigated four years after an experimental inoculation of seedlings with Myrothecium
roridum, an endophytic fungus hypothesized to modify host microbiomes and
potentially defend against white pine blister rust. Foliar fungal endophyte
richness, Shannon diversity, and endophyte community composition varied across
genetic maternal trees, although these effects were potentially confounded with
spatial location. Foliar carbon and nitrogen isotopes, and carbohydrate
composition were each unassociated with endophytic diversity or community
composition after controlling for spatial effects. Endophytic communities did
not vary with the inoculation treatment, nor was the inoculant detected
systemically in inoculated seedlings. We draw two conclusions from this work:
(1) fungal microbiomes of whitebark pine seedlings across our study site did
not vary with host phytochemistry indicative of ecophysiological status, (2)
the inoculation of P. albicaulis seedlings with M. roridum did
not lead to persistent systemic changes in seedling foliar microbiomes.