Plant-microbiome networks impact plant productivity and mitigate plant disease and food safety risks in hydroponic production

Our long-term goal is to understand how to manipulate, in a predictable manner, agricultural microbiomes within hydroponic systems to enhance system resiliency, improve plant health, and reduce human pathogen persistence. Using lettuce hydroponic systems as a production model we will study the root, water and surface microbiomes and strategically manipulate abiotic and biotic variables to identify and optimize production practices that will improve plant health and reduce food safety and plant disease risks. This proposed work will improve our understanding of how microbiomes contribute to and shape measures of plant productivity and health and can serve as a model system for testable microbiome studies. We predict that validation of the use of hydroponic system as a model for the study of microbiome dynamics will enhance our ability to better understand more biologically complex microbiome systems such as those found in soils that are inherently harder to study and predictably manipulate. For this, we have assembled a team of researchers that uniquely complement expertise in hydroponic plant production, plant microbiome research, biological control, and food safety; as well as have access to a network of stakeholders in Ohio and surrounding states, and other resources for successful completion of the proposed experiments. The specific objectives of this proposal are:Objective 1. Determine the diversity and abundance of the resident microbiome in commercial nutrient film technique (NFT) and deep water flow (DWF)lettuce hydroponic operations. We hypothesize that system setup characteristics, including water source and design (DWC vs. NFT), are the greatest drivers of commercial production microbiome differences. Specifically, DWC systems will have a more stable and diverse microbial community than NFT and a greater abundance of beneficial microorganisms due to the lower frequency of water change and lower water flow.Objective 2: Determine system management parameters that promote greater functional diversity of the resident microbiome in hydroponic lettuce production. We hypothesize that nutrient solution conditions which promote plant growth will also promote microbial growth and diversity. However, changes in nutrient conditions or concentrations that lead to less-than-optimal growth will likely lead to an increase in overall microbial abundance, but a decrease in microbial diversity and function, which could in turn increase pathogen persistence.Objective 3: Evaluate hydroponic system resilience to plant and human pathogens, as a function of system management. We hypothesize that system management parameters that promote both plant growth and microbial functional diversity (as determined in objectives 1 and 2) will result in lower human and plant pathogen survival and colonization in the system.