Date Published: March 14, 2016
Publisher: Public Library of Science
Author(s): Tao Ding, Ulrich Melcher, Lorenzo Brusetti.
Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant’s growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.
Endophytic bacteria are harbored inside healthy plant tissues but do not lead to pathogenic reactions , and play important roles in phytoremediation[2–5], biological control against insects or pathogenic microorganisms [6, 7], and plant growth promotion [8–10]. Endophytic bacteria may also be pathogenic to other plants, animals, especially cattle, and human beings [11–14].
The present study is the first to apply next generation sequencing on the leaf endophytic bacterial communities harbored on multiple species of non-cultivated plants. After denoising sequencing errors and chimeras, we obtained 335 97% sequence similarity OTUs from the sequencing of a 700bp fragment of 16S ribosomal DNA gene, representing 16 bacterial phyla, 31 classes, 50 orders, 110 families and 221 genera. Plant leaves cover a significant proportion of the land area of the earth, and thus also provide habitats for colonization of a high diversity of microorganisms. This study provided a survey of the distribution of leaf endophytic bacteria harbored in non-cultivated plants, making an important contribution to the bacterial diversity research of the ecosphere.