Endomycobiotas of the last four cohorts of Abies balsamea needles display relatively similar diversities but different compositions. uncultured fungus

The aim of this study was to identify the foliar endomycobiota associated with Abies balsamea and measure the effect of time of exposure to the environment on both its biodiversity and composition. Based on 256 samples from 16 healthy looking individuals of balsam fir trees collected at 2 locations within the Forêt Montmorency research forestnorth of Quebec City, we first show that the diversity among the last four cohorts of needles was mainly conserved with only a temporary increase for 2-year old needles, while evenness remained stationary. Then, we demonstrate that each cohort harboured a distinct community, for which a relative heterogeneity was observed, impairing the definition of a core microbiota spread over the different needle ages. This hints towards a more dynamic process of colonization of foliar tissue by fungal endophytes than the accumulative one observed with culture-dependent methods. Together, our results suggest that the foliar endomycobiota of balsam fir trees might be more sensitive to the environment than anticipated and quickly shifts its composition to adapt to changing conditions affecting its host.