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Do grafting and rootstock genotype affect the rhizobiome? A study of tomato systems

Ravin Poudel: Plant Pathology Department, University of Florida

<div>Root and rhizosphere microbiomes are critical for supporting nutrient exchange between plants and the bulk soil environment, and determining plant performance and health. We explore how rootstock genotype affects these microbiomes, with the hypothesis that rootstock genotypes have distinct microbial communities. We grafted scion BHN589 on tomato rootstock genotypes (N=4), and profiled the associated root and rhizosphere microbiomes by sequencing hypervariable regions of bacterial 16s rRNA and hypervariable fungal Internal Transcribed Spacer (ITS) regions. The majority of observed microbial taxa were shared across the rootstocks, while a small percentage (less than 3%, p <0.05) of microbial variation in ordination analysis was associated with genotype. Study site and root-rhizosphere compartment explained the majority of the observed variation in the microbial community across all the rootstock genotypes. A significantly more diverse community was observed in the higher yielding rootstock (Maxifort) compared to the controls. In addition, our analysis of microbial-association networks suggested higher microbial interactions for Maxifort in both the compartments. These results indicate a potential role of the rhizobiome in mediating the effects of grafting in vegetable production. Future approaches to modification of the rhizobiome may enhance disease management in this and related systems, when rootstocks are used to enhance disease resistance.</div>