Red Rose IWLA Lancaster PA - - American Chestnut Trees

The American Chestnut Tree - An Historical Perspective

According to the US Department of Agriculture, the American Chestnut tree was the giant of the eastern U.S. forests - sometimes reaching a height of 100 feet with trunk diameters well over 10 feet. There were once billions of them - they accounted for one in five trees along the mountain chain - and their range stretched from Georgia and Alabama to Michigan. But at the turn of the 20th century, a disease called chestnut blight swept through Eastern forests and devastated the species. (See the William Powell TED Talk - "Reviving the American forest with the American Chestnut")

The Work In Progress

Even if the fungus kills a tree, it can't kill the roots. Those survive, gathering nutrients until they can once again grow. Over time, the root system rallies in a quest for survival and sprouts a new series of growth in an effort to regrow the tree. But while new growth might develop, it will not last; after a few years the fungus will once again re-infect the tree. The stump and roots will once more go dormant until they rally yet again and the cycle repeats.

The American Chestnut Foundation, in partnership with the State University of New York's College of Environmental Science and Forestry (SUNY-ESF) take a complimentary approach to traditional breeding: biotechnology. They transgenically add a gene from wheat called oxalate oxidase. (OXO) The OXO enzyme breaks down the the oxalic acid the blight uses to attack American Chestnut trees. (See this short video on how the OXO enzyme works.)

As none of the American Chestnut genome has been removed or replaced, these trees can now be cross-pollinated with existing wild-type American Chestnut trees; over several generations, this will increase the genetic diversity of the blight-tolerant population. Currently, there are over 1000 wild-type American Chestnut trees preserved in "orchards" to use as parent trees for genetic diversification.

The transgenic "Darling 58" founder tree is now under review by federal regulators, to approve distribution of transgenic trees for restoration purposes. Current plans are to create three other transgenic founder trees to alleviate the "founder bottleneck" as transgenic founder trees are outcrossed to wild-type trees.

As an American Chestnut takes between five and seven years to reach maturity, it's estimated that a blight-tolerant American Chestnut tree will be available for large scale forest restoration 20 to 35 years after federal approval to distribute the trees.

Why It's Important

Why bother? American chestnut trees once provided habitat and a mast crop for wildlife, a nutritious nut crop for humans, and a source of valuable timber. Their bold-grained wood was strong, easily worked, and extremely rot-resistant - used in everything from barn timbers to pianos, split-rail fences to fine furniture. Because of their rapid growth rate and rot-resistant wood, they also have significant potential for carbon sequestration, which w recognize at our national level as important in these days of climate change.

In a good year, a single tree can bear more than a thousand burrs - a prolific bounty that bends that particular chestnut's branches down toward the ground. American chestnuts (also known as the "Bread Tree") are unique among nuts in that their nutmeat is high in carbohydrates rather than oil. They can, like some other low-fat nuts, be dried and ground into flour.

Nutritionally, chestnuts are similar to brown rice, but with twice the protein and 1% of the sodium. The protein is very high quality, with an amino acid balance similar to milk or egg, both of which are considered the perfect protein. They contain high amounts of Tryptophan, Isoleucine, Lysine, linoleic acid and sulfur-containing amino acids. Chestnuts also contain high amounts of potassium and Vitamin K, and Vitamin C, B1, B2, and Niacin in levels similar to fresh fruit.