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- What do we consider natural?
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One of the reasons that people oppose using biotechnology
is because they see it as not natural,
and that it might threaten the wildness of an environment,
but really it's...
Those terms are tricky.
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Could it help us address
some of these forest health threats?
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Biotechnology, in one perspective,
could reduce the wildness of a forest
by being a very specific and targeted human intervention.
On the other hand,
if human activities have introduced
a pest or pathogen to a forest
that's devastating the health of that forest,
and we can use biotechnology to protect that tree species,
could that, in fact, restore the wildness
or naturalness of that environment?
- Genetic engineering might be a tool
for helping to recover the health of our forests.
I think people need to understand what the alternatives are
and weigh them against each other.
It's easier to think about specific examples
than to think broadly.
So let's think about the American Chestnut.
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- The American Chestnut is a really interesting case.
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In the early 1900s,
a Chestnut blight was brought to the United States
on accident.
It was a fungus brought along
with either Japanese or Chinese Chestnuts.
American Chestnut trees had never been exposed
to this fungus before, and they were devastated.
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So the American Chestnut tree is now functionally extinct.
The European American settlers
really relied on the Chestnut masts
for annual income and for subsistence.
There's evidence that the Chestnut
was an important food and product for Native Americans.
So there are a lot of reasons
to want to restore the Chestnut.
That's a tree that was really important ecologically,
and also socially.
But it's also an interesting case
because those forests have essentially recovered.
Other trees have come to take their place,
and so we can ask the question,
are those forests healthy?
Would they be more healthy if they had Chestnuts in them?
There are likely to be differing opinions.
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- What they did was crossbreeding American Chestnut
with this Chinese Chestnut.
We all know the American Chestnut, right?
A very large and big tree.
If we look at the Chinese Chestnut, it's very different.
It's a little bit smaller; it's a little bit thinner.
It has less branches.
When you crossbreed them,
they will have 50% of DNA from the American Chestnut
and 50% of the DNA from the Chinese Chestnut.
So it's not a real American Chestnut; it's a hybrid.
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- [Jason] The genetically engineered American Chestnut tree
has a particular gene, from wheat,
that detoxifies the fungus.
- [Doria] In other words,
this gene from wheat inoculates the tree against the blight,
and therefore if we can figure out
how to make sure that it's a durable change,
"durable" meaning that not only will it last
in the tree in which the gene is implanted,
but in the progeny,
then, of course,
you can drive a trait through the population.
- Scientists have invested a lot of efforts
into producing new variants of genetically modified trees.
To date, not a single genetically modified tree
has been used in either the wild, natural forest
or in managed forest plantations.
Genetically engineered American Chestnuts
are currently undergoing USDA regulatory review,
and, if approved, will shortly thereafter
be planted in the Appalachian mountains.
- And the question will be,
how it will it work in the forests?
While there have been field trials
that show some real promise,
in terms of stands of trees being resistant to the blight,
we don't really know how this technology will behave
in the forest over decades and over centuries.
And really, that's the timeline we're talking about
when we think about healthy forests.
You know, as a society, we're going to have to accept
that kind of uncertainty
if we want to move forward with that intervention.
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- CRISPR-CAS genome editing
creates a novel mutant that is genetically indistinguishable
from natural variations.
- We're just modifying a couple of letters.
That is what you can do with CRISPR-CAS.
So in this case,
you will not be adding new information to the genome,
only modifying a couple of letters.
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- One of the arguments for the CRISPR technology
is that it's much more analogous
to what can happen naturally in nature
or through conventional selective breeding,
so nothing different than what we've been doing in the past.
- Making things that could potentially occur naturally
in a wild population is what is the most unique benefit
of CRISPR-based genome editing.
- And some scientists argue
that if you can't distinguish between a gene-edited plant
and one made through conventional breeding,
why would we treat it any differently?
Why would we regulate a gene-edited plant differently
if we might've been able to make it
with conventional breeding?
- Using the more emergent, robust,
and efficient and safe CRISPR editing approach
is one of the more promising ways
in which we can accelerate the genetic improvement of trees
for specific climate change issues,
such as drought tolerance, invasive pests and pathogens,
how trees alter their nutrient uptake.
- One of the challenges is that trees
are very large organisms,
and they live a long time.
And so scientists, really,
they like to work on organisms that are small,
easy to have in a laboratory,
and have very short generation times, like fruit flies.
Trees are not good laboratory organisms,
and they take many years
until they're at reproductive maturity.
- They also typically have very complex metabolisms
and a genetic makeup.
For example, coniferous trees, like pines and firs,
have genome sizes that are five to tenfold
the size of a human genome,
and this makes genetic engineering and CRISPR-based editing
of trees particularly challenging.
- So the kinds of experiments that are necessary
for us to find the genetics or the phenotypes
that would be resistant to a pest or pathogen,
that can take a really long time.
Also, there's always some degree of uncertainty
because a laboratory experiment or a field trial
can't perfectly capture the entire complexity
of an ecosystem over time,
especially when we're talking about forest trees
that live a very long time.
- The decision on whether
a genetically restored tree species
is going to be the right alternative,
is not gonna be an all or none.
It's not gonna be all trees we need to restore this way.
Physically, we can't do it.
Economically, we can't do it.
Scientifically, we can't do that.
It's gonna be a species-by-species decision.
These kinds of decisions
resonate with how people see the woods,
how they view wildness,
how they experience nature.
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