Plant Invasions Are Associated with Changes in Root-Zone Bacterial Communities.

The importance of interactions among plants, soil and microbes is well acknowledged. Although it is observed that invasive plant species alter the natural ecology, the cause-effect relationships with soil and microbes is not well established. Control and management of invasive plants requires the understanding of the associated soil and root-zone microbiome.  We aimed to understand whether the bacterial communities in the root-zone changed between three different invasive and native plants. Towards this end, we sampled root-zone soil (15-cm deep) from sites growing the invasive plants: Microstegium vimineum, Rhamnus davurica and Ailanthus altissima. As reference, we identically sampled root-zone soil of native plants from an adjacent transect. To identify the bacterial community composition and structure we performed Illumina MiSeq sequencing of the 16S rRNA gene and analyzed the data using QIIME. Rarefaction analyses using the Faith's Phylogenetic Diversity, observed species and Chao1 metrics indicated increased alpha-diversity in the rhizosphere bacteria of A. altissima and M. vimineum as compared to their corresponding references. Beta diversity analyses using both unweighted and weighted Unifrac indicated differences in the bacterial composition and structure respectively in rhizosphere of invasive and native plants. Three dimensional principal coordinates analysis revealed clustering of samples as per habitat and species. The unweighted and weighted Unifrac accounted for 24% and 68% variation, respectively, in Axis 1 of PCoA. Overall, these results were consistent with the main hypothesis that bacterial communities in the root-zones of invasive plants were different from adjacent native plants, but further studies need to be performed to investigate whether microbes support or help to maintain invasions.