Abstract:
Invasiveness and the impacts of introduced plants are known to be mediated by plant-microbe
interactions. Yet, the microbial communities associated with invasive plants are generally poorly
understood. Here we report on the first comprehensive investigation of the bacterial and fungal
communities inhabiting the rhizosphere and the surrounding bulk soil of a widespread invasive tree,
Acacia dealbata. Amplicon sequencing data indicated that rhizospheric microbial communities differed
significantly in structure and composition from those of the bulk soil. Two bacterial (Alphaproteobacteria
and Gammaproteobacteria) and two fungal (Pezizomycetes and Agaricomycetes) classes were enriched
in the rhizosphere compared with bulk soils. Changes in nutritional status, possibly induced by
A. dealbata, primarily shaped rhizosphere soil communities. Despite a high degree of geographic
variability in the diversity and composition of microbial communities, invasive A. dealbata populations
shared a core of bacterial and fungal taxa, some of which are known to be involved in N and P cycling,
while others are regarded as plant pathogens. Shotgun metagenomic analysis also showed that several
functional genes related to plant growth promotion were overrepresented in the rhizospheres of A.
dealbata. Overall, results suggest that rhizosphere microbes may contribute to the widespread success
of this invader in novel environments.
