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American Chestnut + Chinese Chestnut
Maryland Content Standard
• Students will use information about how the transfer of traits from parent or parents to offspring occurs, to explain how selective breeding for particular traits has resulted in new varieties of cultivated plants and domestic animals
Student Objective
Students will be able• to identify the fungus that causes the blight and the differences between plants and fungus. •To map out the backcross strategy used to make blight resistant American Chestnut Tree.
What is a Fungus?
• The blight is caused by a fungus
Cryphonectria parasitica
• A member of the fungus kingdom– A heterotroph/consumer (eats something
else)• Specifically a decomposer that eats dead,
decaying matter
– multicellular
Fungus Reproduction
• Reproduces asexually– They create spores which float through air
and land on substances– If the substances meet the 4 basic needs of
the spore, it will grow into the fungus• Food, water, space, oxygen
– As it grows, it reproduces asexually and creates more spores
• This is how the fungus spread over the entire east coast
How Does it Kill the Tree?
• The spores enter through openings or wounds in the bark
• The fungus grows in and under the bark, girdling the cambium.– Cambium is the only living
layer of the tree– Girdling means to
surround the tree, eating into the living layer
• It kills the tree above the point of infection by cutting off it’s supply of water and nutrients
Lets think about this….
• Using what you now know about the Blight write a persuasive paragraph persuading your county representative to give your organization funding for research and conservation of the American Chestnut Tree
How to fix it?
Backcrossing
What are we looking for?
• High Resistance From Blight
Chinese Chestnut
American Chestnut
What is a Back-Cross?
-You take two different trees (Chinese and American) and cross them.
-Then you keep crossing the offspring with the American Variety
What does the do?
• We want a tree that is mostly American Chestnut (15/16) that has the blight resistance from its Chinese Chestnut ancestor
Lets See…
As a class lets diagram our own backcross
Activity
• Complete the “Bean There Done That” activity to demonstrate your ability to perform a ‘mock’ backcross.