Adverse growth conditions can lead to decreased plant growth, productivity, and survival resulting in poor yields or failure of crops and bioenergy feedstocks. In some cases, the microbial community associated with plants has been shown to alleviate plant stress and increase plant growth under suboptimal growing conditions. A systematic understanding of how the microbial community changes under host stress conditions is required to understand the contribution of the microbiome to water utilization, nutrient uptake, and ultimately yield. In this work we were interested in studying the response of a common, defined microbiome to diverse, environmentally imposed host stress conditions. To approach this, we inoculated clonal, axenic, Populus deltoides rooted cuttings with a common microbiome, allowed the cuttings to grow and acclimate to the greenhouse, then subjected a subset of the plants to a water limited treatment, metal toxicity, and shading treatment. We measured the plant physiological, transcriptomic, and metabolomics response of the plant and used 16S amplicon sequencing to study the response of the root and rhizosphere microbiome.
Results/Conclusions
While plant responses to treatments in growth, photosynthesis, gene expression and metabolite profiles were varied, we identified a core set of bacterial genera that change in abundance in response to host stress. The results of this study indicate substantial structure in the plant microbiome community and identify potential drivers of the phytobiome response to stress. The identification of a conserved “stress microbiome” indicates tightly-controlled relationships between the plant host and bacterial associates, and a conserved structure in bacterial communities associated with poplar under different growth conditions. The ability of the microbiome to buffer the plant from extreme environmental conditions coupled with the conserved stress microbiome observed in this study suggests an opportunity for future efforts aimed at predictably modulating the microbiome to optimize plant growth.