Genotype, Tannin Capacity, and Seasonality Influence the Structure and Function of Symptomless Fungal Communities in Aspen Leaves, Regardless of Historical Nitrogen Addition

Abstract

Background Plant mycobiomes play a crucial role in plant health, growth, and adaptation to changing environments, making their diversity and dynamics essential for agricultural and environmental contexts, including conservation efforts, climate change mitigation, and potential biotechnological applications. Horizontally transferred mycobiomes are established in plant organs, yet the dynamics of their colonization and establishment remain unknown. New molecular technologies offer a deeper insight into the establishment and dynamics of plant-associated mycobiomes. In this study, we investigated leaf-associated mycobiomes in cloned replicates of aspen (Populus tremula) with naturally varying phenolic profiles and a history of nitrogen fertilization. Main findings Using ITS2 metabarcoding of 344 samples collected from a ca ten-year-old common garden with small aspen trees at various time points over two consecutive years, we identified 30,080,430 reads in our database, corresponding to an average of 87,448 reads per sample clustered into 581 amplicon sequence variants (ASVs). Analysis of ASV patterns revealed changes in both richness and abundance among genotypes and across the seasons, with no discernible effect of fertilization history. Additionally, the number of reads was negatively correlated with the ability of the genotypes to synthesize and store condensed tannins.