Course-based undergraduate research experiences (CUREs)

The goal of the “Plants fight back” CURE is to develop peptide-based biofungicides for control of fungal diseases in crops. Fungal diseases cause 12-15% yield loss in crops, and some fungal pathogens produce mycotoxins that pose a major threat to human and animal health. Fungal diseases such as wheat head scab, wheat rusts, rice blast and sheath blight, soybean rust, and banana black sigatoka are a major threat to food security and food safety globally. The fungicide market is therefore projected to be a $17 billion industry by 2022. However, fungal resistance to fungicides and environmental damage are major global challenges that often follow increased application of fungicides. Some plants demonstrate antifungal properties when attacked by fungal pathogens via compounds (antifungal defensins) that inhibit the growth of the attacking fungi thereby limiting infection. All higher plants in the plant kingdom produce antifungal peptides, such as defensins, during their normal growth and development and in response to pathogen attack. For example, Alfalfa (Medicago sativa) produces a defensin during seed maturation that has been demonstrated to exhibit broad spectrum activity against plant fungal pathogens. Radish (Raphanus sativus) produces an antifungal defensin in the seed and protects it from fungal attack during germination and early seedling growth. Harnessing these plant-generated peptide-based biofungicides provides a more environmentally sustainable approach to fungal disease control.

Research question/theme:
In this CURE, undergraduate students in collaborative teams will design and conduct experiments in their classrooms to generate new discoveries on the potential of  antifungal plant defensins and NCR peptides from a species of Medicago truncatula to control gray mold disease caused by Botrytis cinerea in relevant food crops e.g. tomatoes, strawberries, grapes, lettuce and flowers (for example, roses). This CURE lab can be integrated into several undergraduate labs e.g., microbiology, mycology, plant physiology, and botany-related lab courses.

Student learning objectives from this activity:
Students will gain an understanding of fungal biology and be able to answer the following:

• How do fungal pathogens infect host plants?
• What is the disease cycle of a fungal pathogen (for example: Botrytis cinerea)?
• How do plants fight back against fungal pathogens?
• How do scientists grow fungi in vitro?
• How do scientists purify antifungal peptides and determine their antifungal activity?
• How do scientists perform in-planta infection assays and record fungal infections under laboratory conditions?

Method:

• Grow cinerea fungal pathogen in the laboratory.
• Purify recombinant defensin peptide using chromatographic techniques
• Inoculate seedlings of your chosen food crop with cinerea fungal pathogen and apply plant defensins in planta (drop-inoculation or spray assay method).
• Incubate plants for ~ 48 hours
• Fungal disease scoring (lesion size) using an imaging device.
• Analyze images using Image J software for Antifungal activity of plant defensins against cinerea

Options for potential food crop plants to use in Plants Fight Back include:

• Tomato
• Lettuce
• Apples
• Grape
• Strawberry
• Raspberry
• Bell peppers