American Chestnuts from ArcheWild
ArcheWild is now releasing blight-resistant American chestnut trees to land managers, nurseries, parks, and committed homeowners. Our chestnuts are the progeny of still-existing stands of American chestnuts that have successfully resisted the chestnut blight (Cryphonectria parasitica).
For curation purposes, our chestnuts should be recorded as blight-resistant Castanea dentata, 3rd generation, ‘Lee’ strain. These terms are explained below.
Blight resistance refers to the trees’ ability to survive the chestnut blight to varying levels of degree. Since these trees are open-pollinated (i.e., not clones), some trees will exhibit more blight resistance and some less. Many of these trees will survive a minimum of 20-30 years and set viable fruit. Some trees are likely to live for much longer; some might die before they reach 15 years old. Because these are real trees with real genes, there is no way to pre-determine how any individual will perform.
See Figure 3 to see the 2016 size of our 2nd generation, ‘Lee’ strain mother trees.
Morphological testing of our chestnuts suggests the presence of some Castanea pumila genes, which might be conferring some resistance. Castanea pumila, which ArcheWild also grows, is a smaller native American chestnut.
Castanea dentata is the accepted botanical name for these trees, so as to distinguish them from the Chinese-American cross (Castanea mollissima x dentata).
3rd generation means that these chestnuts are the grandchildren of the original, pre-blight Castanea dentata trees. The blight-resistant characteristics of these original trees have been passed, in varying degrees, to their children, or 2nd generation trees, in our orchard. Not all of the 2nd generation trees survived, but only those that survived to seed-bearing age and have good height and structure have been selected (see Figure 2) for producing our 3rd generation trees.
ACCF is the acronym for the American Chestnut Cooperators’ Foundation, which is a network of land managers that share seeds and genetic material from still-existing stands of wild American chestnut for breeding purposes. There are two other American chestnut recovery efforts. For more information about the different programs, read the American Chestnut Recovery Efforts section below.
‘Lee’ strain is the reference code used to track performance of various seed lots. All progeny of our American chestnuts should be recorded as ‘Lee’ strain chestnuts, along with their generation. For example, if you buy our 3rd generation ‘Lee’ strain chestnuts and they survive to seed-bearing age and you plant their nuts to make new trees, they should be recorded as 4th generation, ‘Lee’ strain chestnuts.
Delivery or shipping is available. Call 855-752-6862 or write email@example.com to order by April 15, 2021. ArcheWild is only offering tubelings in 2021.
American Chestnut Recovery Efforts
The American Chestnut Cooperators’ Foundation (ACCF) is dedicated to breeding American chestnut strains from the many healthy stands and trees found throughout their range. Although less well-funded than ACF, this program is real and producing good results. Trees from this strain get the blight, they all do, but the severity of the infection does not greatly disfigure the tree and generally does not kill the tree.
Several universities are investing in probably the best solution to the problem – a genetically modified American chestnut tree that successfully resists the fungus. These trees are not yet ready for the general market, but they should be within a decade or so. Read the article excerpt below describing this research effort. In the meantime, the ACCF chestnuts do not represent a threat to future plantings of GMO chestnuts like the 10s of thousands of Chinese-crossed trees do, which have been unfortunately planted in our forests.
One genetic tweak
“Our efforts focus on direct genetic modification, or genetic engineering, as a way to bring back the American chestnut.
Thirty days after infection with chestnut blight, the wild-type American chestnuts on the left are wilted, while the ‘Darling 54’ transgenic trees are doing well. (See Figure 3).
We’ve tested more than 30 genes from different plant species that could potentially enhance blight resistance. To date, a gene from bread wheat has proven most effective at protecting the tree from the fungus-caused blight.
This wheat gene produces an enzyme called oxalate oxidase (OxO), which detoxifies the oxalate that the fungus uses to form deadly cankers on the stems. This common defense enzyme is found in all grain crops as well as in bananas, strawberries, peanuts and other familiar foods consumed daily by billions of humans and animals, and it’s unrelated to gluten proteins.
We’ve added the OxO gene (and a marker gene to help us ensure the resistance-enhancing gene is present) to the chestnut genome, which contains around 40,000 other genes. This is a minuscule alteration compared to the products of many traditional breeding methods. Consider the techniques of species hybridization, in which tens of thousands of genes are added, and mutational breeding, in which unknown mutations are induced (i.e. the ACF program). Genetic engineering allows us to produce a blight-resistant American chestnut that’s genetically over 99.999 percent identical to wild-type American chestnuts.”
Chestnuts currently available from ACF have historically been crossed with Chinese chestnuts and they are, in our opinion, being released prematurely. The original premise was to cross with Chinese chestnuts to pick up the disease resistance genes and then back-cross the Chinese morphological traits back out. This is at least a 100+ year process and ACF is nowhere near completing this program. Yet ACF is aggressively marketing their product.
“Well, (ACF) trees are already in the forest so Chinese genes are already there. What’s the big deal if you plant more?” Resist this argument. Just as ecologists curse the USDA for the spread of Rosa multiflora and the National Wild Turkey Federation for the spread of Russian olive trees, please don’t let future generations curse you or your organization for planting Chinese chestnut genes in our forests.
The Smithsonian writes, on May 10, 2015, that, “There has been an effort — ongoing in the 100 years since the blight — to create blight-resistant American chestnuts by cross-breeding with Chinese chestnuts, and the American Chestnut Foundation (ACF) has had some success on that front, but it hasn’t yet achieved its goal.”
ACF is investing heavily in the GMO chestnut, which we believe is a smart move. We hope that Chinese crossed chestnuts eventually disappear from the market.