Abstract Presented at Plant Biology 2019

Rajnish Khanna¹, Priyanka Mehta¹, Norma Morella², Elijah Mehlferber², Riley Mahn¹, Roberto Bogomolni³, Kent F. McCue⁴, and Britt Koskella².

¹i-Cultiver, Inc., 404 Clipper Cove Way, San Francisco, CA

²Department of Integrative Biology, University of California, Berkeley, CA

³LOVNod Biosciences, 404 Clipper Cove Way, San Francisco, CA

⁴USDA-ARS, 800 Buchanan Street, Albany, CA

In previous experiments, Berg and Koskella (Current Biology 28: 2487, 2018) have shown that phyllosphere (above ground) microbiota of tomato provide protection against plant pathogens in nutrient- and dose-dependent manner. We have investigated whether these phyllosphere microbes from field-grown tomato leaves improve nutrient assimilation and increase tomato yield in greenhouse-grown tomatoes, ultimately providing a benefit to the tomato industry. Foliar application of microbiota from field-grown tomatoes on to leaves of greenhouse-grown tomatoes alone resulted in increased tomato production and tomato weight. We have also extended the experiments to measure the effects both of phyllosphere microbiota and Azomite^® volcanic ash fertilizer (AZOMITE soil products, LLC). Two formulations of Azomite^® (Granulated and Ultrafine) were tested. The Granulated formulation applied at start of sowing and planting promotes vegetative growth, early flowering and fruiting (tomato quantity), whereas the Ultrafine product application once every week on top soil increases tomato weight and fruit pigmentation (tomato quality). Combination of these treatments with the natural tomato leaf phyllosphere microbiota produced the best results. We are currently carrying out 16S rRNA gene sequencing to determine microbiome dynamics between soil, rhizosphere, root and phyllosphere, and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES) analyses to quantify the flux of nutrient elements between soil and tomato plants. These results will be used to draw any functionally significant correlations between the phyllosphere microbiota (through whole genome sequencing), and plant assimilation of available nutrients from soils treated with or without Azomite^® volcanic ash fertilizer, potentially providing novel methodologies to increase yield in agricultural context.