Nanotechnology in agriculture: Balancing crop protection and food safety

Reference Presenter Authors
Jason Christopher White White, J.C.(Connecticut Agricultural Experiment Station); Achieving and sustaining global food security will become increasingly difficult as a changing climate increases crop loss due to greater pest and pathogen activity. Nano-enabled agrichemical delivery platforms offer a unique potential to manage pathogens and increase productivity with reduced negative environmental consequences. Work at the Connecticut Agricultural Experiment Station is focused on the use of nanoscale micronutrients to suppress crop diseases through modulation of plant nutrition. Much of the focus has been on using micronutrient nanofertilizers to manage soil-borne fungal pathogens such as Fusarium and Verticillium, with the intent of uncovering mechanisms of action and of developing applications that can readily be applied to the field. In one series of experiments, the potential of several Cu nanomaterials to enhance the nutrition and growth of tomato, eggplant, watermelon, and soybean upon fungal infection was evaluated. The particles were foliarly applied once (100-500 mg/L; 1-2 mL dose) to seedlings prior to 30-40 days of growth in the greenhouse or full life cycle in field studies. Fungal infection reduced plant growth by up to 65% across all species but foliar amendment with nanoscale Cu significantly reduced disease. For example, disease was reduced by 31-40% in tomato, resulting in significantly greater plant mass. Similar findings were reported for field studies with soybean, eggplant and watermelon. In tomato and watermelon, the time-dependent expression of several genes integral to plant defense was shown to be uniquely modulated by nanoscale Cu and Si amendment. Importantly, these nanoscale material-induced changes in expression correlated well with positive changes in disease suppression and plant growth. However, any application of nanotechnology in agriculture must include a thorough understanding of the potential implications of this strategy. For example, work from our group has shown that certain nanoscale materials may offer some benefit to the plant but may also cause negative changes in the microbial community in the plant rhizosphere. We analyzed the metatranscriptome of the maize rhizosphere and observed multiple unintended effects of 117-d exposure to 100 mg/kg nanosilver. The Archaea population was reduced by 30%, and as such, their involvement in nitrogen cycling was compromised. In addition, certain potentially phytopathogenic fungal groups showed significantly increased abundance, likely due to the negative effects of nanosilver on bacteria that exert natural biocontrol against these fungi as indicated by negative interactions in a network analysis. Collectively, these results highlight the potential of nano-enabled strategies to increase food production but also highlight the importance of gaining a thorough understanding of the relevant mechanisms of action so as to ensure the safety and sustainability of these approaches.
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