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.Bean There Done That