Lesson 3: Chestnut Blight

Introduction:

This lesson provides basic information about fungi and detailed information about Cryphonectria parasitica, the fungus that infects the American Chestnut tree. It is broken into 3 steps; step 1, information about the fungus, step 2 allows students to grow common fungi found from spores in the air, step 3 show how the fungus affects the function of the tree.

Learning outcomes:

Students will be able to describe conditions about which fungus can grow and where they are found. Students will also be able to define vascular tissue and tell how the blockage of vascular tissue affects a plant.

Curriculum alignment:

Biology Goal 4: 4.01 – Compare eukaryotic kingdoms (fungi and plants) emphasizing the methods of getting food. 4.02 – Transport in vascular plants

Classroom time required:

Step 1: 40 minutes (may be assigned outside of class)
Steps 2 and 3: 20 minutes with 10 minutes for observation on 3 subsequent days

Materials needed:

Copies of “Chestnut Blight” handout and Biology textbooks (1 per student), 1 petri dish filled with nutrient agar per every 2 students, clear tape or Parafilm for closing petri dishes, 1 50mL beaker per every 2 students, red food coloring, celery – 3 stalks (with leaves) for every group of 2, 1 ruler, 1 magnifying lens, and one scalpel or pair of scissors for every group of 2

Technology resources:

None required

Pre-activities:

Prepare a copy of the “Chestnut Blight” handout to give to each student. Gather items listed in materials section. If not using already prepared agar plates, melt nutrient agar and pour into plates. Make sure to immediately replace lid to keep plates sterile. Store plates upside down until ready to use. Keep celery refrigerated until ready to use.

Activities:

1. Handout “Chestnut Blight” copies to each student. Have students read the article about the Chestnut blight fungus. Then have students use their textbook to look up information about general characteristics of fungi. The article and book information are to be used by students to answer questions and define words located under “Step 1.” This step may be given as a homework assignment to be completed the day prior to the final 2 steps.
2. Verbally check with students to be sure that they understand general information about fungi such as: Fungi prefer cool, moist, dark environments; spores of a fungus are their reproductive structures; mycelium are the “body” of fungi and this is where extra-cellular digestion and absorption occur; finally, if a fungus lives off of another organism and causes it damage it is considered to be a pathogen. Also, make sure that students understand that vascular bundles are the “circulatory system” of plants. Water and minerals are transported through this.
3. Group students by two’s and have them gather petri dishes, marking utensil, celery, beaker, tape, ruler, scalpel or scissors, and food coloring. They should begin “Step 2” at this point. Step 3 can be set up while the petri dishes are allowed to sit exposed to the open air.
4. Students will need to check the progress of the fungus growth in the petri dishes and the movement of water in the celery for 3 more days. Give about 10 minutes of class time each each for observation and data recording. On the final day, give an additional 10 minutes to write final summary under Step 3, or let students complete summary for homework.

Assessment:

Check “Step 1” for correct responses to definitions and questions. “Step 2” is only to be checked for completion of drawings for each day. If a group does not have fungal growth on their plate, it is acceptable for them to view another group’s fungus. Day 4 should be the most detailed drawing. “Step 3” contains a chart that should be assessed. The control should show even movement of water to the entire stalk. The stalk with 1 notch should show movement to all areas except the area above the notch. The leaf above this area may be slightly withered. The stalk with 3 notches will have movement of water up to the notches and almost none above this. The leaf of this stalk will be significantly withered. Finally read the summary paragraph for this step to make sure that students understand that significant damage to the vascular tissue of the plant will significantly damage, or even kill, the plant.

Modifications:

Students with learning disabilities or limited English proficiency should be paired with another student to complete “Step 1.” Be sure to be available to answer vocabulary related issues for these students. These groups may need additional time to complete the assignment. Drawings should not be a factor in grading unless not completed.

Alternative assessments:

Students with learning disabilities or limited English proficiency may be allowed to complete the definitions and questions on the computer to help with vocabulary, spelling and grammar. This may require additional time for completion of this portion.

Critical vocabulary:

• Ascomycete : any of a group of higher fungi (as yeasts or molds) with septate hyphae and spores formed in asci
• Ascospore: any of the spores formed by ascomycetes
• Blight: an organism (such as a fungus) that causes disease
• Cambium: a thin layer between the xylem and phloem of most vascular plants that gives rise to new cells and is responsible for secondary growth
• Canker: an area of dying material in a plant
• Conidia: an asexual spore produced in certain fungi
• Fungus: any of saprophytic and parasitic spore-producing eukaryotic typically filamentous organisms that lack chlorophyll and include molds, rusts, mildews, smuts, mushrooms, and yeasts
• Mycelium: the mass of interwoven filamentous hyphae that forms especially the vegetative portion of a fungus and is often submerged in another body (such as organic matter or the tissues of a host)
• Spore: a primitive usually unicellular often environmentally resistant dormant or reproductive body produced by fungi
• Parasite: an organism who is dependent on something else for existence or support without making a useful or adequate return
• Pathogen: a specific causative agent of disease
• Vascular bundle/ tissue: a strand of specialized cells of higher plants consisting mostly of xylem and phloem