It protects the tree by breaking down a toxin created by the blight fungus ... through The American Chestnut Foundation’s backcross breeding program are a cross between Chinese and American trees.

From left to right, the trees are a blight-susceptible wild-type American chestnut (C. dentata) called Ellis 1, a blight-resistant Chinese chestnut (C. mollissima) tree called 'Qing,' and two ...