Constructed Communities of Populus and Bacterial Isolates to Study Microbiome Function
D. PELLETIER (1), C. Timm (2), A. Carrell (3), S. Jawdy (3), L. Gunter (3), Z. Yang (3), J. Aufrecht (3), T. Lu (3), N. Engle (3), T. Tschaplinski (4), G. Tuskan (3), M. Doktycz (3), D. Weston (3) (1) Biosceince Division, Oak Ridge National Laboratory, U.S.A.; (2) Bioscience Division, Oak Ridge National Laboratory, U.S.A.; (3) Biosceince Division, Oak Ridge National Laboratory, U.S.A.; (4) Biosceince Division, Oak Ridge National Laboratory, U.S.A.

The function of the plant-microbiome system is a result of complex interactions between microbiome members, environmental factors and the host plant. To constrain these variables, we are studying constructed communities which consist of diverse, microbial isolates obtained from natural systems. Using genomic content, strain functional data, and microbiome community data as a guide, we select communities of organisms to colonize axenic Populus cuttings in microbiome replacement experiments. In a two-member microbiome, a Pseudomonas representative and a Burkholderia representative from our isolate collection were chosen based on predicted and observed metabolism of plant hormones, the ability to grow using plant metabolites as sole carbon sources, and the enhancement of root growth in plate assays. When inoculated on Populus cuttings, the resulting host phenotype was explained by the combination of the two individual effects, supported by transcriptome and metabolome data. In ongoing work, we have begun studying two 10 member communities of bacterial isolates each from two Populus species. The 10 strains represent abundant and diverse orders in natural Populus microbiomes, including α-, β- and γ- Proteobacteria, Bacilli, and Actinobacteria. Communities increased root growth when inoculated on axenic host plants and were both dominated by Burkholderia and Pantoea strains, despite isolation from different hosts and different genomic content. Finally, we observe positive and negative correlations between community members in replicate samples, an example of emergent behavior that would not be observed in one-on-one studies or genera level sequencing studies. These promising results provide a foundation for future constructed community studies.

Abstract Number: P4-113
Session Type: Poster