Diversity analysis of the rhizospheric and endophytic bacterial communities of Senecio vulgaris L. (Asteraceae) in an invasive range.

Dandan Cheng,Liang Feng,Hongmei Wang,Zhongsai Tian,Lin Xu

doi:10.7717/peerj.6162

Abstract

Increasing evidence has confirmed the importance of plant-associated bacteria for plant growth and productivity, and thus it is hypothesized that interactions between bacteria and alien plants might play an important role in plant invasions. However, the diversity of the bacterial communities associated with invasive plants is poorly understood. We therefore investigated the diversity of rhizospheric and endophytic bacteria associated with the invasive annual plant Senecio vulgaris L. (Asteraceae) based on 16S rRNA gene data obtained from 57 samples of four Senecio vulgaris populations in a subtropical mountainous area in central China. Significant differences in diversity were observed between plant compartments. Specifically, the rhizosphere harbored many more bacterial operational taxonomic units and showed higher alpha diversity than the leaf and root endospheres. The relative abundance profiles of the bacterial community composition differed substantially between the compartments and populations, especially at the phylum and family levels. However, the top five phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Acidobacteria) accounted for more than 90% of all the bacterial communities. Moreover, similar endophytic communities with a shared core set of bacteria were observed from different Senecio vulgaris populations. Heavy-metal-resistant, phosphate-solubilizing bacteria (Brevundimonas diminuta), nitrogen-fixing bacteria (Rhizobium leguminosarum), and cold-resistant bacteria (Exiguobacterium sibiricum) were present in the endosphere at relatively high abundance. This study, which reveals the structure of bacterial communities and their putative function in invasive Senecio vulgaris plants, is the first step in investigating the role of plant–bacteria interactions in the invasion of this species in China.

Highlights

The advent of globalization has increased the frequency of invasive species outbreaks (Hulme, 2009)
Core bacterial operational taxonomic units (OTUs) in the root and leaf endospheres From the 1,284 OTUs in the leaf endosphere, we identified 36 OTUs with >0.70 rf as core OTUs that collectively comprised more than 70% of the leaf endophytic bacterial communities (Table S4)
We determined that the bacterial communities associated with Senecio vulgaris were primarily influenced by plant compartments, as the alpha diversity was significantly decreased in the root and leaf endospheres compared with the rhizosphere soil (Fig. 3; Table S3)

Summary

Introduction

The advent of globalization has increased the frequency of invasive species outbreaks (Hulme, 2009). Invasive plants can displace native species, destroy the structure and. There are concerns that the constant expansion of invasive plants reduces the uniqueness of local flora and even leads to the global homogenization of species composition (Orians & Ward, 2010). To control the invasion of exotic plants, it is essential to understand the mechanisms of the invasion process; this topic has become one of the core research areas of invasion ecology

Methods

Results

Discussion

Conclusion