Recipient Organization
UTAH STATE UNIVERSITY
(N/A)
LOGAN,UT 84322
Performing Department
Biological Engineering
Non Technical Summary
Climate extremes are exposing crops and ornamental grasses to increasing drought stress. Drought is predicted to reach historic extents in the southwest and central USA this century, exacerbated by increasing demands in human water consumption. Estimates are that landscape irrigation, including turfgrass, in arid regions of western North America use 45 to 60% of municipal freshwater resources. This research aims to improve drought stress response in plants through applications of a plant-protective osmolyte (glycine betaine) that is delivered via highly porous silica particles. This research will test the osmolyte nano-silica formulation in two grasses: wheat (Triticum aestivum) a staple food crop, and a perrenial ryegrass (Lolium perenne). Silica is itself a micronutrient for plants, providing potential secondary benefits. The selected grasses will be treated via foliar applications and contrasted with soil applications of the glycine betaine nano-silica formulations. In this manner the modes of osmolyte / nano-silica uptake and distribution in the plants will be characterized in order to develop formulations that provide the greatest benefit to the plants. The vigor of treated and control plants will be measured before, during, and after imposed drought conditions. The efficacy of the osmolyte formulations will be assessed through shoot length, shoot mass, photosynthetic efficiency, and stimulation of additional osmolyte production in the treated plants (i.e., a "priming effect" where the externally applied osmolyte induces a defense response in the plants). The nano-carrier is selected to deliver the glycine betaine payload to the plant, bypassing soil and plant-associated microbes that might consume the payload before it reaches the target plant tissues. The anticipated benefits from this research will impact a wide range of stakeholders. Municipal water rationing of lawns, golf courses, sports fields, etc., may find greater compliance if a robust recovery could be demonstrated by a single application of the osmolyte formulation before an extended water withholding period. For food crops such as dryland wheat, the osmolyte application may bridge crop survival until the next rain.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
This research aims to improve abiotic stress response in two grasses: wheat (Triticum aestivum), and a perrenial ryegrass (Lolium perenne), through exogenous osmolyte (glycine betaine) delivery via highly porous silica nanocarriers capped with Pluronic F68.Objective-1. (a) Prepare and characterize nanocarriers for osmolyte (glycine betaine) delivery and utilization by wheat and ryegrass (b) Characterize glycine betaine encapsulation and release behaviorObjective-2. Assess the nano-formulations benefit to plant survival and recovery following drought stress.For both objectives, photosynthesis efficiency, nutrient acquisition, plant mass and morphology will be measured to understand mechanisms by which plant vigor (in drought-tolerant cultivars) is supported before, during, and after droughting.
Project Methods
Objective-1a.Prepare and characterize F68-capped GB-loaded nano-SiO2.The basic materials for the proposed formulation are commercially available GRAS compounds used in agriculture, foods, and pharmaceuticals: nano-porous fumed SiO2 (Aerosil 200, Evonik Industries) nominal particle size < 50 nm, 200 m2/g surface area (highly porous); Pluronic F68 (P188 BASF), and GB (Trimethyl glycine, Sigma Aldrich). The formulations will be prepared following the procedures already developed in the PI lab (Cartwright et al., 2022, 2023). GB is adsorbed electrostatically through its quaternary ammonium group with loading optimized through pH adjustment. The particles will be characterized using dynamic light scattering, zeta potential, and high resolution microscopy.Objective-1b.Characterize GB encapsulation and release behavior.Assess protection of GB from soil microbes when GB is encapsulated in the pores of nano-SiO2 through growth assays where the carbon source in the bacteria growth medium is replaced with free or encapsulated GB. GB release from bare and F68-capped SiO2 NPs into ddH2O and sterile filtered soil pore waters will be characterized using the periodide method. The release of the F68 capping layer from the SiO2 will be monitored using fluorescein-F68 (fF68), with SiO2 labeled with rhodamine allowing simultaneous tracking, with FRET used to distinguish free fF68 from fF68-rhodamine-SiO2. These fluorophores will also report on nano-carrier uptake by the plants All results will be contrasted with free GB to optimize GB loading and release.Objective-2. Demonstrate drought-stress mitigating activity of F68-capped GB-loaded nano-SiO2 in drought-tolerant wheat and turfgrass cultivars in growth chambers.Turf grass: Studies will be performed in greenhouse facilities using normal (75% field capacity) water-deficit growth conditions (35 % field capacity) over 10 weeks with two cultivars differing in drought responses (ASP and AberMagic). The grasses will be raised for 6 weeks before the soil (sterile quartz sand or calcareous Millville from USU Experimental Farm) is treated by defined doses of the nanocomposite (100 and 500 mg/pot; 1 kg of soil per pot) in the watering solutions. Measurements will include water use (determined by pot weight every 2d normalized by measurements of soil without plants), and growth potential (determined by plant cover and cutting shoots weekly to assess trimmings dry mass).Plant vigor will be determined in-situ through efficacy of photosystem II determined with the photosynthesis analyses (LICOR 6800) with grass shoots at 10 weekly intervals. At harvest at 10 weeks after treatment, shoots will be examined to assess trichomes/unit length. Measurement of shoot water content will determine if this was improved by the nano-formulations. In addition to assaying GB content in plant shoots systems-level responses to the treatments and drought will be studied by measuring proline (another osmolyte of importance to plant abiotic stress response) levels, and correlating the concentrations of both GB and proline osmolytes with photosystem II efficacy.Wheat:Studies will be performed in parallel to the turfgrass approaches, utilizing the selected growth media. There will be five treatments, with each of the three independent studies having three separate pots as replicates. The treatments are: (1) Watered with no additions (135 ml/800 g soil); (2) Watered with F68/GB nano-SiO2 treatment (135 ml/800 g soil); (3) Drought stress no F68/GB nano-SiO2 (20 ml/800 g soil); (4) Drought stress with F68/GB nano-SiO2 treatment (20 ml/800 g soil).Surface sterilized seeds (10% H2O2 15 min) will be planted in sterile growth medium (9 seeds/800 g soil) in pots. Water capacity for normal growth will be 135 g water per pot. Watering will include 20 ml of half-strength Hoagland's solution for complete mineral nutrition at 7, 14, 21, 28 d after planting. The test treatments (100 and 500 mg nano-formulation /kg soil) will be added during watering at 14 d. Water deficit will begin following normal growth at 14 d and imposed for 14 d. Water will then be added back to the level maintained for all watered plants. Images will be taken daily to record chlorosis, wilting, and drying of the tissues, and plant vigor. Photosystem efficiency will be measured at 14 d, and every 2 d until harvest. Harvest will be at 36 d when plant growth/survival will be assessed. Accumulation of protective osmolytes, glycine betaine, and proline in the shoots will be measured with established procedures. The timing of the drought period may be modified to generate lesser or greater stress to identify drought recovery limits for selected application rates.