Conservation of Endophyte Bacterial Community Structure Across Two Panicum Grass Species.

Esther Singer,Jason Bonnette,Thomas E Juenger,Tanja Woyke

doi:10.3389/fmicb.2019.02181

Esther Singer, Jason Bonnette + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2019.02181

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Abstract

Panicum represents a large genus of many North American prairie grass species. These include switchgrass (Panicum virgatum), a biofuel crop candidate with wide geographic range, as well as Panicum hallii, a close relative to switchgrass, which serves as a model system for the study of Panicum genetics due to its diploid genome and short growth cycles. For the advancement of switchgrass as a biofuel crop, it is essential to understand host microbiome interactions, which can be impacted by plant genetics and environmental factors inducing ecotype-specific phenotypic traits. We here compared rhizosphere and root endosphere bacterial communities of upland and lowland P. virgatum and P. hallii genotypes planted at two sites in Texas. Our analysis shows that sampling site predominantly contributed to bacterial community variance in the rhizosphere, however, impacted root endosphere bacterial communities much less. Instead we observed a relatively large core endophytic microbiome dominated by ubiquitously root-colonizing bacterial genera Streptomyces, Pseudomonas, and Bradyrhizobium. Endosphere communities displayed comparable diversity and conserved community structures across genotypes of both Panicum species. Functional insights into interactions between P. hallii and its root endophyte microbiome could hence inform testable hypotheses that are relevant for the improvement of switchgrass as a biofuel crop.

Highlights

Most land plants grow in intimate association with a complex microbiota
We investigated the belowground bacterial communities of switchgrass and its model relative, Panicum hallii
We analyzed the microbial communities retrieved from plant root compartments of two P. virgatum and two P. hallii ecotypes planted at two sites in Texas (Figure 1)

Summary

Introduction

Most land plants grow in intimate association with a complex microbiota. A number of recent studies in various plants showed that root microbiome compositions are impacted by planting sites/soil types (Lundberg et al, 2012), plant species as well as among genotypes within a single species (Schweitzer et al, 2008; Bever et al, 2012; Lundberg et al, 2012; Wagner et al, 2016a). While differentially abundant microorganisms may be linked to, e.g., cultivar-specific recruitment factors, such as host genetic regions, core microbiomes allow insights into inherited microbial players that may have evolved together with their hosts across genotypes, species, and even sites (Whitham et al, 2006).

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