郭華仁 基改美國栗抗病效果並不佳
郭華仁 基改美國栗抗病效果並不佳
原本在美國、加拿大很普遍的美國栗(Castanea dentata)在20世紀前半葉受到來自日本的栗枝枯病菌嚴重威脅。紐約州立大學環境科學與林業學院在2013年與美國栗子基金會(TACF)合作，將小麥基因轉殖到美國栗，並於2018年向農部申請基改栗’ Darling 58’免管理而可種於森林。此基改栗被廣泛宣傳為復育美國栗的靈丹妙藥。
不過鑒於’ Darling 58’的效果出現問題，因此栗子基金會(TACF)於本月初宣布不支持’ Darling 58’的野外種植，因此其他民間團體呼籲農部撤銷該項申請。
科學家發現’ Darling 58’長得比較慢、比較矮，抗栗枝枯病菌的效果也不好。該基改栗的風險評估僅限於溫室，無法反映自然狀態，而管理單位的能力仍然無法審核其在野外的天然授粉問題。
1.
https://www.gmwatch.org/....../20343-the-american......
2. https://responsibletechnology.org/press-release....../
PRESS RELEASE: RESEARCHERS TEMPER
EXPECTATIONS FOR GENETICALLY ENGINEERED AMERICAN CHESTNUT TREE – REVEAL
UNEXPECTED PROBLEMS
COALITION OF GROUPS CALL ON US DEPARTMENT
OF AGRICULTURE TO REJECT DEREGULATION
New York – During a recent webinar called a
“Chestnut Chat,” organized by the American Chestnut Foundation (TACF), GE
chestnut researchers walked back earlier promises and projections for
restoration of the American Chestnut through the use of genetically
engineering.
During the “Chestnut Chat” several
startling admissions were made including that the “Darling 58” (D58) GE
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 GE 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 GE trees.
“Now they admit that things are not going well with it. It is clear the USDA
must not deregulate this GE 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) GE 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 GE chestnut. Now that problems are being identified with
the GE 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
GE American chestnut trees with other GE 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 organizations 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 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 GE American
