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Oral: Metagenomics and the Phytobiome


Root and rhizosphere microbiome responses to new tomato rootstock systems
R. POUDEL (1), L. Meyer (2), A. Jumpponen (3), M. Kennelly (4), C. Rivard (2), B. Cordova (5), J. Brisbane (5), K. Garrett (5) (1) Plant Pathology Department, Institute for Sustainable Food Systems, and Emerging Pathogens Institute, U.S.A.; (2) Horticultu

Grafting tomato scions onto rootstocks can increase yields by providing disease resistance, stress tolerance, and increased vigor. We hypothesized that grafting affects the rhizosphere microbiome, or rhizobiome. We analyzed impacts of grafting scion BHN589 with two rootstocks BHN1028, RST-04-106 on the rhizobiome of tomato plants using rRNA gene sequences, including non-grafted and self-grafted controls. We also compared the microbial communities in roots vs. rhizosphere. In the first year, there were no observed effects of grafting or rootstock on microbial diversity in the three farm sites. Many OTUs were shared (72% in bacteria, 65% in fungi) among treatments, while some taxa were treatment-specific. Across all grafting treatments, higher diversity was found in the rhizosphere compared to the roots (p<0.001). Composition of the rhizobiome varied with root-rhizosphere compartment and farm site. Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Planctomycetes were most abundant in all treatments, with the latter three being less abundant in roots. Pezizales, Cantharellales, and Xylariales were enriched in roots, whereas Pleosporales, Mortierellales, and Hypocreales were enriched in the rhizosphere. Interestingly, community modularity was higher in the roots compared to those from the rhizosphere. Ultimately, understanding rhizobiome responses to rootstocks will support vegetable production, rhizobiome-based crop breeding, and disease management.