Co-occurrence pattern of bacteria and fungi on the leaves of invasive aquatic plant Alternanthera philoxeroides.

The microbes that are attached to aquatic plants play critical roles in nutrient cycles and the maintenance of water quality. However, their community compositions, biodiversity, and functions have not been well explored for the invasive plants in inland waters. Here, the co-occurrence patterns between bacteria and fungi on the leaves of Alternanthera philoxeroides and their potential ecological interactions were studied during the growing seasons. Along with significant variations in the alpha diversity of attached microbes over time, shifts in their community composition were significantly associated with the dynamics of plant stoichiometry, substrate composition and extracellular enzyme activity. Deterministic processes (heterogenous selection) play predominant role in community assembly of the attached bacteria, while stochasticity (undominant process) was the major driver for the attached fungi assembly. Compared to free-living microbial network, attached microbial network was structurally simple but highly modular. The attached microbes had more intra-phylum links (primarily within the phyla Actinomycetota, Alphaproteobacteria, Bacillota and Basidiomycota) and distinct co-exclusion patterns between bacteria and fungi in the modules. In summary, the study of microbial community composition, biodiversity, community assembly processes and species interactions in the phyllosphere will be helpful in understanding the impact of biological invasion on the aquatic biodiversity and ecosystem function.