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

Abstract

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 a predominant role in community assembly of the attached bacteria, while stochasticity (undominated process) was the major driver for the attached fungal assembly. Compared with the free-living microbial network, the 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 will be helpful in understanding the microbes and their interactions in the phyllosphere of A. philoxeroides, an key invasive species under national management and control.

Keywords: co-occurrence networks; community assembly; invasive macrophyte; phyllospheric microorganisms.