The Populus Microbiome Atlas Project - Dissecting the microbiome landscape of an important economic and ecological model.
C. SCHADT (1), M. Cregger (2), M. Crouch (2), A. Veach (2), Z. Yang (2), T. Lu (2), N. Cude (3), P. Busby (4), K. Hameed (4), R. Vilgalys (4), T. Rials (5), C. Pan (6), S. Jun (6), I. Nookaew (6), D. Ussery (2), M. Podar (2), S. Tringe (8), G. Tuskan (2), D. Pelletier (2) (1) Oak Ridge National Laboratory, U.S.A.; (2) Oak Ridge National Laboratory, U.S.A.; (3) Novozymes Corporation, U.S.A.; (4) Duke University, U.S.A.; (5) University of Tennessee, U.S.A.; (6) Oak Ridge National Laboratory, U.S.A.; (7) Oak Ridge National Laboratory, U.S.A.; (8) DOE Joint Genome Institute, U.S.A.

Populus trees are broadly distributed in nature, widely used in pulp and paper production, and a potentially an important bioenergy feedstock. We examined 30 different plant tissue/habitat types across contrasting Populus deltoides and P. trichocarpa x deltoides (TxD) for microbiome composition by 16S rRNA gene (bacteria) and ITS2-rRNA (fungal) regions for community comparisons across 300 samples encompasing multiple tissue types. For select habitats we also apply a differential centrifugation method to enrich the microbial cells from plant tissues prior to DNA extraction and metagenomic sequencing to avoid host contamination. For each tree type, bacterial community structure from rRNA gene amplicons varied significantly across leaf, stem, roots and soil/rhizosphere tissue/habitat types. Leaf and stem habitat types had significantly lower OTU richness compared to root and stem habitats and featured decreasing abundance of Proteobacteria from leaf, to stem, to root, to soil. The oldest woody stem tissues were also distinguishable from the younger 1st and 2nd year tissues, and featured enrichment of Firmicutes, consistent with potentially anaerobic environments. Within the leaf, stem, root, and soil habitats, bacterial community structure in P. deltoides samples could be differentiated from TxD hybrid samples. Fungal ITS2 amplicon sequencing of these samples is ongoing after procedures were optimized to incorporate improved primer designs. Comparative metagenomics-based analyses and amplicon-based datasets in general show a high degree of congruence and reduced host DNA contamination to < 2%. The results from this work should greatly enhance our understanding of plant microbiomes in this important model species.

Abstract Number: P4-118
Session Type: Poster