GREEN BIOINSPIRED GLYCOLIPIDS AS MULTI-PURPOSE AGRICHEMICALS

The agricultural industry is facing significant and dynamic challenges to meeting future demand in light of a growing population and increasingly uncertain weather patterns. The United Nations Food and Agriculture Organization has outlined some major trends that threaten the sustainability of food systems and the capacity to meet food needs: increasing extreme weather events and disasters; increasing resource-, energy-, and emission-intensity of the global food systems; slowing growth in plant yields; the undermining of agriculture outputs from food loss and waste; increasing degradation and exploitation of natural resources, loss of biodiversity, transboundary spread of pests and diseases, water scarcity, and soil depletion. Development of a next generation of agrichemicals is needed to meet these challenges. Such agrichemicals should be innovative, environmentally-compatible materials that support agricultural productivity, sustainability, and resiliency to ensure long-term food security.To this end, green bioinspired glycolipids represent a new class of multipurpose agrichemicals that has potential to meet the dual challenge of dust suppression and control of targeted soil pests without harm to important soil quality parameters. The overall goals of this project are to determine the efficacy of glycolipids as agrichemicals for dust suppression and biocide activity and to evaluate potential ecological risks to plants and aquatic organisms that may occur from their use. To accomplish these goals, there are three specific aims:Specific Aim 1: Determine dust suppression by a suite of glycolipids in the context of (1) agricultural field soils, and (2) unpaved access roads. Glycolipid dust suppression will be assessed using the Environmental Protection Agency's Air Quality Index for particulate matter (specifically for particles less than or equal to 10 and 2.5 micrometers) with the 'Good' metric indicating successful treatment. There are two objectives within this aim:Objective 1: Elucidate Suppression of dust emissions from agricultural field and road soils.Agricultural field preparation activities such as plowing, discing, planning, and tilling account for 82% of agriculture's dangerous respirable dust. Dusts also regularly arise from surrounding access and haul roads. Dust suppression using glycolipids will be examined for soils from both field and road sources.Objective 2: Determine durability of treated samples to environmental factors.A sub-set of the three most successful glycolipids from Objective 1 will be subjected to environmental stressors in each soil type to evaluate the longevity of the treatments. The samples will be exposed to UV radiation, heat, or water to evaluate resistance to environmental exposures. Treatments will undergo compression force testing to determine the resistance of the treatment to mechanical disruption (e.g., vehicle traffic). A durometer will measure the compressive hardness. A MTS mechanical tester will test compressive strength and toughness.Specific Aim 2: Evaluate glycolipid biocidal activity against economically important fungal and bacterial pathogens found in dryland crops. We will perform an oomycete pathogen survey on Arizona vegetable crops and nursery plants. The diversity of these pathogens will be determined and individual species recovered then evaluated for potential risk to crop health through pathogenicity tests. Representative isolates will be selected and further evaluated in the lab, then greenhouse, then plant nursery to identify the most potent glycolipids to suppress crop diseases. There are 4 objectives within this aim:Objective 1: Identify and characterize nine species of oomycete pathogens in Arizona.A pathogen survey will be conducted in vegetable fields in Arizona to collect three isolates each of Phytophthora capsici, P. parsiana, P. nicotianae, Pythium aphanidermatum, and P. myriotylum. Pathogen identification and characterization will be performed using morphological and molecular methods. Pathogenicity tests will ensure that these pathogens will be able to infect plants.Objective 2: Determine in vitro sensitivities of various crop pathogens to glycolipids.Using five economically important pathogens, we will determine the inhibitory and lytic effect of each glycolipid compound on mycelial growth, sporangia production and germination, and zoospore production and lysis, and germination of each isolate.Objective 3: Determine in vivo efficacy of glycolipids in disease suppression in greenhouse.The three most promising glycolipids will be advanced to in vivo evaluation using peppers and lettuce plants. These glycolipids along with a nontreated control will be evaluated for suppression of root rot on pepper plants and Pythium wilt on lettuce when applied at a single rate in soil that are inoculated with zoospores.Objective 4: Mitigate pathogen accumulation in the containment basins and redistribution through irrigation system in a Tucson plant nursery.The most effective glycolipids will be used to treat recycled irrigation run-off water in a Tucson plant nursery where high levels of Phytophthora and Pythium species are present in its irrigation system. Irrigation water will be treated with the glycolipid to determine efficacy in pathogen inactivation.Specific Aim 3: Determine the ecological risks of glycolipids to aquatic microorganisms and agriculturally important and native dryland plants. A suite of tests will be used to describe glycolipids' toxicity and potential environmental hazards to determine their risk as agricultural amendments. Such characterizations for agrichemicals are especially important given the quantities released into the environment and inevitable transport into surrounding environmental compartments via various transport modes. This initial ecological assessment will focus on risks to aquatic systems and plants to account for run-off from fields and effects on both crops and surrounding flora. There are 4 objectives within this aim.Objective 1: Assess aquatic prokaryotic acute toxicityAcute aquatic toxicity to prokaryotic organisms will be established using the Microtox assay and the model bacterium Aliivibrio fischeri. The Microtox assay assesses toxicity by determining the effective concentration (EC50) at which a toxicant reduces bioluminescence by 50% relative to a toxicant-free control, and it is commonly used as a rapid, cost-effective screening assay for aquatic toxicity.Objective 2: Assess acute plant phytotoxicityGrowth chamber studies will assess potential short-term phytotoxicity effects of the glycolipids at multiple fixed concentrations. Seed germination tests will be performed using five plant species: lettuce, chile pepper, low woolly grass, tanglehead, and bush muhly. The germination percentage of each species will be obtained, and the average germination time and rate of the treated plants will be compared with untreated controls.Objective 3: Assess long term phytotoxicity - single dose tests.A set of greenhouse studies will test the chronic phytotoxicity of the glycolipids on native plants at single fixed doses. A noninvasive phenotyping method based on rhizotrons will be performed to continually monitor both aboveground plant metrics and root system development using multi-temporal digital imaging. Rhizosphere samples will be analyzed for microbial diversity analysis and above ground biomass will be collected to assess plant fresh and dry weight. EC25 and No Observed Adverse Effect Concentrations (NOAEC) for plant performance will be identified.Objective 4: Assess long term phytotoxicity - multiple dose testsA second set of greenhouse studies will test the effects of multiple applications at fixed concentrations on plant growth. The respective EC25 and NOAEC for multiple traits related to plant performance will be identified.