After years of hype, researchers temper expectations for GM American chestnut tree – reveal unexpected problems

During a recent webinar called a “Chestnut Chat”, organised by the American Chestnut Foundation (TACF), GM chestnut researchers walked back earlier promises and projections for restoration of the American Chestnut through the use of genetic engineering.

During the “Chestnut Chat”, several startling admissions were made including that the “Darling 58” (D58) GM American chestnut tree is not the silver bullet once promised for restoration. It was revealed that the tree grows more slowly and shorter than once thought, blight tolerance is not reliable, and field trials are limited in their ability to reflect real life conditions.

In light of these revelations, the Campaign to STOP GE Trees is calling for an immediate rejection by the USDA of the pending petition to deregulate the D58 GM American chestnut tree.

“For years, the American Chestnut Foundation has been overpromising this genetically engineered tree as the best way to save the American chestnut,” said Lois Melican, who resigned as President of the Massachusetts-Rhode Island chapter of TACF over TACF’s support for GM trees. “Now they admit that things are not going well with it. It is clear the USDA must not deregulate this GE [genetically engineered] tree. That is the only safe and reasonable action given the limitations and uncertainties being acknowledged by the researchers themselves.”

In the early 20th century, the American chestnut, a keystone species in eastern forests, was decimated by an introduced blight. Researchers at the State University of New York’s College of Environmental Science and Forestry (SUNY-ESF) are using genetic engineering methods to try to create a blight-tolerant American chestnut tree. In 2018, SUNY-ESF petitioned the US Department of Agriculture’s Animal Plant Health Inspection Service (USDA-APHIS) for permission to release their “Darling 58” (D58) GM chestnut into wild forests to intentionally cross with wild trees and self-spread. This would be the first time that a genetically engineered plant is released to purposefully spread in the wild. USDA-APHIS has not released a final decision.

Originally researchers argued that the process of USDA deregulation would demonstrate the safety and effectiveness of the blight tolerant GM chestnut. Now that problems are being identified with the GM tree, researchers admit they need deregulation to enable them to test out the tree in wild forest conditions. Researchers also confirmed that they are seeking deregulation of the D58 because it will ease deregulation of future GM American chestnut trees with other GM traits.

“With all of the acknowledged problems the D58 chestnuts have, the USDA must not deregulate them. If these faulty GE trees are planted in our forests, their experimental GE seeds and pollen will inevitably and irreversibly contaminate wild American chestnuts growing in the forest.” said Anne Petermann of Global Justice Ecology Project. “Far from ‘restoring’ the American chestnut, the deregulation of the GE chestnut could spell their ultimate demise. The idea that researchers still want deregulation so they can plant these GE trees in the forests, knowing they have problems that they don’t understand, is incomprehensible.”

The Campaign to STOP GE Trees  is a North American and International coalition of organisations with a mission to prevent the large-scale release of genetically engineered trees into the environment.

The Campaign published a white paper on the issues and concerns with genetically engineering the American chestnut: Biotechnology For Forest Health? The Test Case of the Genetically Engineered American Chestnut (2019)

 
MEDIA BACKGROUNDER:

To learn more about the what was presented at the “Chestnut Chat”, and the stark contrast between previous hype and current reality regarding the genetically engineered D58 American chestnut, see the Media Backgrounder below:

“Chestnut chat” on Darling 58, hosted by The American Chestnut Foundation (TACF), September 15th, 2023.

In the TACF “Chestnut Chat” webinar of September 15, researchers from The American Chestnut Foundation (TACF) and the State University of New York’s College of Environmental Science and Forestry (SUNY-ESF) presented updates to the chestnut restoration community and general public about the “Darling 58” (D58) genetically engineered (GE or genetically modified) American chestnut tree. They provided more realistic and nuanced information about the D58 project than much of the hype previously created by TACF and SUNY-ESF about this GE tree. They also confirmed that, contrary to prior promises, members of TACF or the public will not be able to receive nuts or seedlings from the GE American chestnut even if it is deregulated.

“D58 is a really big step, just the idea of using a transgenic tree … The D58 isn’t going to solve chestnut restoration and biotechnology in general isn’t going to be the best tool to deal with all of these threats.”
– Andrew Newhouse, director of the American Chestnut Research and Restoration Project, SUNY-ESF.

TACF Chestnut Chat Speakers:

Andrew Newhouse, Director of the American Chestnut Research and Restoration Project at SUNY-ESF
Sara Fitzsimmons, Chief Conservation Officer, TACF
Jared Westbrook, Director of Science, TACF
Patrícia Fernandes, Assistant Director of the American Chestnut Research and Restoration Project, SUNY-ESF
Vasiliy Lakoba, Director of Research at TACF’s Meadowview Research Farms

There are six key updates from the researchers:

1. The researchers state that the genetically engineered tree D58 is not the silver bullet for restoration of the American chestnut as had been widely promoted.

Deregulation (government approval in the US) does not mean that the GE tree will work as the promised “restoration tree”. Vasiliy Lakoba, Director of Research with the American Chestnut Foundation, stated that “trees live on tree time, and ultimately restoration is going to happen on tree time,” and, “It’s important to understand that [these early] results, just because they’re available immediately, doesn’t mean they’re robust long term or that they’ll hold up.”

2. D58 appears to grow more slowly and is shorter than trees that do not inherit the gene.

Researchers stated that in trials “trees that inherit the [blight tolerance] gene are maybe 20% shorter than their full siblings that did not inherit the gene.” They attributed this to the fact that the blight tolerance gene is switched on at all times, causing the organism to run a constant “low-grade fever”, inhibiting the energy it can put towards growing. The researchers also stated that It is too early to tell how this might impact the competitiveness of the tree.

3. D58’s blight tolerance trait will not be very effective in many trees that inherit it.

Researchers acknowledged that the blight tolerance trait as observed in the young D58 trees is not very effective. This is of particular concern because tolerance to the blight is known to weaken as American chestnut trees get older, and not all trees that inherit the blight tolerance gene will exhibit tolerance.

4. Blight tolerance from the OxO gene from wheat is not sufficient. Additional GE traits will be needed to make future GE trees viable.

Researchers discussed their experiments with adding (stacking) additional GE traits to make the D58 tree viable, including, but not limited to, more blight tolerance capacity, Phytophthora root rot resistance, and tree growth enhancement. Even if successful, blight tolerance may not be sufficient for American chestnut restoration. Patrícia Fernandes, Assistant Director of SUNY-ESF’s chestnut program, stated: “We are looking into enhancing the resistance beyond what OxO confers by stacking genes for resistance and we are also looking into stacking genes for root rot resistance …We are using all the tools in the toolbox, so we are looking into genes from resistant Chestnut species, so from Chinese and Japanese chestnuts, but we are also looking into genes from other plant species. “

5. D58 has only been grown under very controlled conditions that do not reflect the realities of natural forest ecosystems.

There is no evidence that any of the results seen thus far in D58 trials will hold up under more unpredictable forest conditions. Lakoba acknowledged that the GE trees “are still growing in a fairly agricultural setting… They’re growing in neat rows, there’s no vegetation within the rows… Really we try to make a fairly comfortable habitat for the chestnuts although this does not approximate their natural forest habitat.”

6. Regulatory agencies are not equipped to properly evaluate the risks of a GE tree designed for cross-pollination in the wild.

Researchers acknowledge that the agencies evaluating the release of this tree have never had an application like this before. Andrew Newhouse stated: “This has been a learning process for the Regulatory Agencies too, because the vast majority of everything they’ve worked on they’ve reviewed and approved in the past has been annual agricultural crops, and even the trees that they’ve approved are things like apples and papayas that are generally planted in one place. [Not] a wild tree that we hope can be planted in the forest and cross with wild relatives… that’s just such a fundamentally new thing for these agencies to deal with.” It is clear that these agencies are not equipped to ask the right questions or properly evaluate risk for D58, and yet will make a decision that could have sweeping impacts for future generations.

The American Chestnut Cooperators Foundation

The Campaign to STOP GE Trees points to the work of the American Chestnut Cooperators Foundation as an example of successful efforts to restore the American chestnut without the need for genetic engineering:

The American Chestnut Cooperators’ Foundation (ACCF) is a nonprofit scientific and educational foundation dedicated to restoring the American Chestnut Tree to its former place in our Eastern hardwood forests. Priorities include the development of blight-resistant all-American chestnuts and economical biological control measures against chestnut blight in the forest environment. ACCF was organized in 1985 and exists as an alternative to hybrid and GE breeding/introduction programs in order to preserve and restore pure American chestnuts to our Eastern Forests. ACCF Founders began breeding pure American Chestnuts for blight resistance individually and collaboratively in 1975.

Their comments to the USDA regarding the petition to deregulate the D58 GM American chestnut can be found here: https://www.regulations.gov/comment/APHIS-2020-0030-13244


Source: Campaign to STOP GE Trees
https://globaljusticeecology.org/https-stopgetrees-org-researchers-temper-expectations-for-ge-chestnut-tree/

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