Support for the American Chestnut is urgently needed

The Darling American Chestnut

Building on decades of careful research, scientists at the State University of New York College of Environmental Science and Forestry (ESF) developed the disease-tolerant ‘Darling 54’ American chestnut tree (Castanea dentata).

Darling 54 is safe, effective, and stable, and will contribute to more resilient forests for future generations. Through extensive testing, these trees have shown a consistent reduction of susceptibility to chestnut blight, and Darling fully meets USDA safety criteria. Leading conservation organizations, scientists, and forest enthusiasts show strong support for Darling. Our forests need the American chestnut, and cultivating the Darling variety is a major step forward to bringing it back.

These may be the first bioengineered organisms with the goal of ecological restoration, and they represent a unique application for this technology to be used for conservation and cultural benefits.

American Chestnut History and Importance

For millennia, billions of chestnut trees reigned over 200 million acres of eastern woodlands, until succumbing to a lethal disease known as the chestnut blight during the first half of the 20th century. Caused by the invasive fungus Cryphonectria parasitica, this blight has been called the greatest ecological disaster to strike U.S. forests in recorded history.

Monarchs of the forest.

American chestnut trees were once the mighty giants of America’s eastern forests, reaching heights as great as 100 feet tall and trunk diameters over 6 feet wide. Fast-growing, rot-resistant, straight-grained, and prolific nut producers, these iconic trees had many exceptional qualities. An ideal building and furniture wood, chestnut lumber was a vital part of the economy. Research studies suggest that American chestnuts may store significantly more carbon than other hardwood species such as oak or hickory.[1]

Producing up to 6,000 nuts annually, chestnuts were a vital food source for humans, livestock, and wildlife.

The blight stripped the forest of this powerhouse species.

In the early 20th century, America lost nearly 4 billion chestnut trees. This fungus attacks the chestnut with toxins, including oxalate, which creates cankers and kills the tree by disrupting the flow of water and nutrients to its branches and stems. Only a small fraction of the original population survive today, and these are generally isolated, stunted in growth, limited in survival, and unlikely to reproduce.

What the American chestnut means to people today.

The American chestnut remains a beloved part of many community and family histories. Today’s volunteers in restoration efforts carry on the legacy of generations who fought to save the species. The American chestnut tree is firmly etched in our cultural memory.

Restoring America’s Most Iconic Tree

Early Struggles

For more than a century, scientists have tried various traditional breeding methods to select for blight tolerance to fungal blight. Current efforts, including Darling, show the most promise for restoring fully American chestnut trees.
A Breakthrough

In 1988, American Chestnut Restoration began collaborating with ESF, the country’s oldest and most respected college dedicated to the environment. In 1990, ESF’s American Chestnut Research and Restoration Project was founded to develop blight-tolerant trees through modern genetic engineering. For thirty-five years, patience and fortitude have kept the project moving forward.
What's Next

ESF has developed the world’s first line of blight-tolerant American chestnut trees, the Darling, and has conducted careful peer-reviewed studies demonstrating Darling‘s environmental safety and blight tolerance. ESF has petitioned three Federal agencies to grant unregulated status to Darling so that distribution and restoration may begin.

Mission

To restore America’s most iconic tree to its full former range in our Eastern forests.

Darling Development Timeline

Darling is safe and effective

Since 2014, ESF’s researchers have worked closely with regulators to demonstrate that the Darling tree is safe and efficacious.

In addition to the environmental tests noted previously, numerous studies have been conducted to ensure the safety and effectiveness of Darling. These include nutritional equivalence analyses and observations of leaf feeding on the development of invertebrates.

Measurements of chestnut growth rates in well-replicated plots have varied widely among chestnut varieties. While differences exist, the vast majority develop several non-lethal cankers and keep growing. In contrast, related non-Darling seedlings are highly susceptible and eventually succumb to the disease.[5] Although such variations make it difficult to compare height growth over time, it is clear that Darling trees have better blight tolerance than any other American chestnut.

Considerations for Restoration

While not strictly necessary for plant pest risk assessment, there are several other features of Darling trees that are important to consider:

Stability of Expression
Ideally, gene expression will be stable across multiple generations. Some crop plants have shown gene silencing or decreased expression in offspring generations, so we have monitored Darling chestnuts very carefully for evidence of this phenomenon. Recently, gene expression in three Darling 54 families was investigated across five offspring generations. While we found fluctuation in expression values as would be expected to result from different environmental conditions and family backgrounds, no indication of gene silencing over five generations was detected. Most offspring tested had higher expression than their progenitors. This result suggests that the OxO gene will continue to impart blight tolerance as it is passed to offspring. A full manuscript describing this study is currently being prepared for publication.

Homozygous Seeds
Restoration and natural reproduction will be accelerated by the production of homozygous trees: those trees with two copies of OxO from two Darling parents. Recently, ESF has reported successful production of healthy homozygous Darling trees, and initial results confirm that more than 99% of their offspring inherited OxO, exactly as expected. Pollen from homozygous trees will be an important tool to maximize the production of blight-tolerant chestnuts and help us conserve rare and valuable trees.

Community of Supporters

This website is maintained by the following organizations, which are actively involved in the research, development, and restoration efforts of the American chestnut.

SUNY College of Environmental Science and Forestry (ESF)
ESF formed the “American Chestnut Research and Restoration Project” in 1990. The project’s pioneering efforts in biotechnology science have resulted in the world’s first lines of blight-tolerant American chestnut trees, the Darling and the DarWin. This noble project was founded and directed by Professors Charles Maynard and William Powell. The current project director is Dr. Andrew Newhouse.

American Chestnut Restoration
This volunteer membership organization supports the restoration of the American chestnut through science-based biotechnology. From its founding in 1990, it has formed a productive partnership with ESF to accomplish this goal. While most of the organization’s members are from New York, American Chestnut Restoration has additional members from more than a dozen other states.

SilvaBio
America’s hardwood forests represent resources of immense cultural, ecological, and economic value. But fungal pathogens threaten to wipe out whole tree species. We are on a mission to bring the American chestnut tree back from functional extinction. Darling represents a breakthrough, making possible the restoration of this iconic tree. We fully support ESF and the many organizations, scientists, and volunteers who made this breakthrough possible. We stand ready to return a keystone species in the eastern forest ecosystem and U.S. economy.

Interested? Contact us.

info@restorechestnut.org