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Hello, my name is Pam Ronald.
Thank you for joining me today with iBioSeminars.
Today I'm going to talk about one of the most important issues of our time.
To introduce you to the subject, I'd like to start with a short video that was put together
by the University of Minnesota's Institute for the Environment.
How do we feed the world without destroying it?
This is the question that my husband, Raoul Adamchak, and I
have been discussing for many years.
Raoul is an organic farmer. Here he is at the UC Davis Student Farm,
talking to his students.
He's been an organic farmer for 30 years, and we've had quite an opportunity
to talk about these issues together.
Some people believe that organic farmers and plant geneticists
represent opposite ends of the agricultural industry,
and some people think we might even not be able to talk to each other.
But, we can. And that's because we have the same goal --
how to create an ecologically-based agricultural system.
Still, many of our friends and family have asked us
if organic agriculture is enough to feed the world.
And they've also asked us, "Are genetically engineered crops
safe to eat and safe for the environment?"
So, in order to answer these questions, Raoul and I recently wrote a book together.
And, in the book, what we tried to do is to introduce the reader
to what an organic farmer actually does
and what a plant geneticist actually does.
So, we take the reader through some events of our days
and answer questions that come up on the topics of farming and food.
So, the first step was to establish criteria for more sustainable agriculture.
And, a sustainable agriculture rests on three pillars: social, economic, and environmental.
For social, it's important that communities have local food security,
and they must have access to abundant, safe, and nutritious food.
In order for an agriculture to be sustainable, the farmer must be able to sell their crops,
and the communities must be economically viable.
The food that's produced must be affordable to community members.
Environmental aspects are critically important, and one of the
goals of sustainable agriculture is to reduce harm to the environment,
reduce energy use, reduce soil erosion, and foster self-fertility.
We also want to minimize use of land and water, and this is very important
because today we have 4-fold reduced access to water,
compared to individuals 50 years ago, and we have very little arable land
left to farm on the planet.
It's also important that crop systems be genetically diverse,
both to reduce the possibility of disease outbreaks and also to foster beneficial insects.
Now, the USDA National Organic Program Standards really evolved in response
to the environmental aspects of conventional agricultural systems.
And I wanted to give you a couple examples of the power of farming practices
to achieve a sustainable agriculture.
So, organic agriculture uses fewer pesticides than many conventional systems,
and one of the reasons is that the National Organic Program Standards
prohibit the use of synthetic pesticides.
This is my husband's farm at the UC Davis campus,
and you can see that he also uses a strategy of genetic diversity.
So, they plant many different types of crops,
and this will reduce harm from pests and disease.
Organic farms are 2x as energy efficient, and they have improved soil fertility,
primarily through the use of the addition of compost and crop rotation.
And as I mentioned, this genetic diversity also enhances microbial and insect diversity,
which is important to maintain these non-harmful insects in the field
because these insects will actually prey on pests that can harm the crops.
So, with all these benefits, many people ask,
"Is organic agriculture enough to feed the world?"
"Can we rest with the USDA National Organic Program Standards,
or are there reasons that we need to look towards the future?"
Now, organic agriculture, like all agricultural systems,
have problems with pests, diseases, and stresses.
And many of these are very difficult to control using organic methods.
Some pesticides used by organic farmers are not sustainable, in the sense that
even though they're not synthetic, some of these pesticides are highly toxic
to animals in the environment.
Although the yields of an organic farm really depend on the farmer,
the crop, the particular year... so it's difficult to generalize
about the yield of organic agriculture,
studies have shown that the yield is 45-100% of conventional systems,
depending on the particular crop and farmer and year.
Organic food is often more expensive than conventionally grown food,
and this can be a problem for low-income consumers.
So, I want to talk about the power of improved seed and discuss
whether modern genetic approaches can contribute to a sustainable agriculture.
In this slide, I wanted to give you a short history of agriculture and plant breeding.
It's estimated that 10,000 years ago, the first primitive domestication was carried out,
in wheat, rice, and corn. A few thousand years later,
the first grafting was carried out in 100 BC. Grafting is mixing two different species
onto one plant, so it's the first example of biotechnology.
Then, we can see, over the last 400 years, there have been many different advances
in plant genetics. So, for example, Gregor Mendel discovered the law of heredity
in 1866. In 1876, the first intergeneric crosses were carried out.
That is two very different species -- wheat and rye --
were combined to develop new varieties,
We also saw the beginning of mutation breeding. So what mutation breeding
is, and we still use it today, is you take a random chemical mutagen...
You take a chemical mutagen or radiation... you randomly mutagenize the entire genome.
So what that means is you're introducing changes to those genes.
And then, what a breeder will do is he'll sort through a lot of those seeds,
and then pick out those that have traits of interest.
So there won't be any information about the genes that have been changed,
but just that there's a new trait.
The first recombinant DNA molecule was discovered in 1973.
And the first genetically engineered crop was engineered in 1993.
So, since that time, we've seen a vast growth
in the development of genetically-engineered crops
and, in fact, in 2005, farmers planted a billion acres of genetically-engineered crops.
And today, I think the cumulative is about 2 billion acres.
So, what is this plant breeding? And just to give you an idea of how dramatically
the plants that we eat today have changed from those of our ancestors,
I show you here teosinte corn on top, and this is the progenitor of modern-day corn.
And the progenitor corn, you have to take a hammer to break it open to release the kernels.
Through a long process of breeding initiated by Native Americans 8,000 years ago,
today we have modern corn, which yields hundreds, if not thousands, more grains per plant.
So this shows you the dramatic power of genetics,
using conventional plant breeding approaches.
This is another example of plant breeding over the ages.
These are versions of a single crop species... these are Brassica species.
And these were developed in Europe over the last 800 years.
So, you can see that plant geneticists have used conventional breeding
to generate dramatically different plants, and of course,
some of us prefer some of these vegetables over others.
So, what is genetic engineering, and what is precision breeding,
and how does it differ from conventional breeding?
And I want to mention that precision breeding is also called marker-assisted breeding,
and it's also a modern genetic approach.
So, with conventional breedings, what I've shown here are, you can imagine two parents,
one in orange, one in red... They each have their own set of genes.
And what breeders have done over the years is, they will take the pollen from one plant,
put it on another and essentially by doing that,
they're mixing all the genes of the two different varieties.
And they end up with a progeny that is a mixture of the two parental genomes.
So, in this case, many uncharacterized genes are mixed together,
and then what breeders will do is they will carry out additional breeding experiments
to try to get rid of unwanted genes.
Now, one important aspect of conventional breeding
is that gene transfer is limited to closely related species.
In contrast, with genetic engineering or precision breeding,
one to few well-characterized genes are introduced.
So, in this case, you can take, for example, one variety,
and you can simply add a gene of interest.
And, with genetic engineering, this gene can come from any species...
so that's a big difference between conventional breeding.
Finally, what you end up with is a new variety that has one gene introduced.
So it's a very precise introduction of a single gene.
So, one big question is ... It's necessary that anything we eat
is safe to eat and safe for the environment.
And so this has been a subject of study or the National Academy of Sciences
in the United States as well as 15 other countries around the world.
And there's a very useful report that can be looked at
called the Safety of Genetically Engineered Foods.
So, this is one of several reports that have been put out
by the National Academy of Sciences.
What we can say is that after planting of 2 billion acres of genetically engineered crops,
there hasn't been a single case of adverse health or environmental impacts.
And this is really important to remember,
because any time we introduce a new plant variety,
whether it's genetically engineered or developed through conventional breeding,
there is always some risk of unintended consequences.
But, importantly, the method of introducing genes through genetic engineering
presents similar risk to the methods of introducing genes
by conventional approaches of breeding.
So, it's not the method of introducing genes that's critical, but it's the product.
What is the variety that's being developed?
And, who do those varieties benefit?
So, because of the importance of looking at the new variety that's developed,
all new crops must be considered on a case-by-case basis.
So, we cannot simply say that genetic engineering is all beneficial or all harmful.
We really need to look at the crops developed through this technique.
So, let me give you an example of one genetically engineered crop
that was developed over several years.
This is a papaya that's infected with papaya ringspot virus.
Plants get viral diseases, as humans get viral diseases.
And this was a particularly devastating disease.
In the 1950s, the entire papaya crop on the island of Oahu
was destroyed by papaya ringspot virus.
And this is devastating to those local farmers as well as to Californians
because we get most of our papaya from Hawaii.
So, growers there had no choice but to move their farms.
There was no conventional way to control this disease.
There was no organic method to control this disease.
So, they moved their farm to the island of Hawaii.
But, in 1992, the same virus was discovered in Hawaii,
and the papaya industry was facing the complete destruction of their industry.
By 1995, the production had plummeted, but at the same time, Dennis Gonsalves,
a local Hawaiian, had been interested in these new techniques of genetic engineering,
and he had been working for several years to try to develop a papaya
that was resistant to this particular disease.
So, what he did was he took a snippet of DNA from a mild strain of the virus
and inserted it into the papaya genome.
So, you can imagine this is similar to human vaccination against a terrible disease.
Although mechanistically it's different, conceptually it's the same concept,
where the plant or the human is inoculated with a mild strain of the virus.
So, this was very successful. The papaya plant was highly resistant to infection.
And, I wanted to show you some data from Dennis Gonsalves and his colleagues
some field experiments.
And this is a papaya farm in Hawaii.
In the center here, you can see the genetically engineered papaya,
and on the outside is the conventionally grown papaya.
This is a natural field infection. So, you can see what a dramatic difference there is
between the genetically engineered papaya and the conventionally grown papaya.
And there was a remarkable comeback of the industry.
You can see here, the first arrow, when the virus was first discovered on the island of Hawaii,
the production plummeted, and after introduction of the genetically engineered papaya,
you can see that production started to climb again.
So, today, virtually all the papaya that we eat here in California
is genetically engineered, and there's still no other efficient method to control this disease.
There's no organic method and there's no conventional means of control.
So, this is an example where genetic engineering was the most appropriate technology to
confront this particular disease.
I wanted to give you a second example.
This is the example of Bt cotton.
What I'm showing you here is the cotton bollworm,
which is an insect coming out of a cotton boll.
Now, this insect is a very serious pest of cotton in the United States and
all over the world.
It's estimated that in the United States, that 25% of all the insecticides we use
are used to control this insect.
Half of those pesticides that are used are considered to be carcinogenic
or potentially carcinogenic.
So, clearly a better method was needed to control this disease.
What geneticists did was they decided to take advantage of
a protein called Bt, which has been used by organic farmers
to control this disease by spraying it on their crops.
So, organic farmers generally take a bacteria that produces this protein,
and they can purchase vats of this bacteria that have been dried
and ground up, and they can spray it on their crops.
So, what geneticists did was to take the gene encoding this protein
and insert it directly into cotton.
And we've had several years now to look at the efficacy of this approach.
So, in Arizona, this is a farmer in his field, and recent studies have shown
that Bt cotton fields use half the insecticide, compared to their neighbors
growing conventional cotton, and importantly, they achieve the same yield,
and they see increased insect biodiversity.
So, these are non-pest insects, which are important because you want to maintain
those non-pest insects because they'll prey upon the pests.
And this insect biodiversity is measured by ant and beetle species abundance.
This genetically-engineered cotton has been grown in India as well,
and cotton farmers in India see approximately a 37% increase in yield.
And the reason for this dramatic increase in yield is that,
in many of these farms in India, farmers cannot afford insecticides,
and so they lose their crop to this pest.
And of course, they are seeing a massive reduction in insecticide.
And importantly, recent studies have shown that the profits that farmers are seeing
are benefitting entire villages.
In China, within a few years after introduction of Bt cotton,
total insecticide use fell by 156 million pounds.
And to give you an idea of this number... what it means...
is in California alone, we use about 180 million pounds of pesticides each year
to control insects and disease.
So, the introduction of a single genetically engineered crop
could eliminate almost the entire amount of insecticide that we use in California.
So, what is the future of genetically engineered crops globally?
Well, today there are 30 commercialized
genetically engineered crops, cultivated worldwide.
Most of the seed is produced by large corporations, such as Monsanto.
By 2015, there will be over 120 crops, and importantly,
these include staple crops, such as potato and rice,
which are critical for feeding people in less developed countries.
So, where will these new varieties come from?
Well, a recent report indicates that half of them will come from
national technology providers in Asia and Latin America, designed for domestic markets.
So, I just want to end, to summarize to say that we really need to take advantage
of the most modern genetic approaches, as well as the best ecological farming practices,
to create an ecologically-based agriculture that will produce enough food
that will be sufficient to feed the growing population.
And I'd like to leave you with a quote by Rachel Carson,
one of the leading environmentalists of our time.
I think she was really looking into the future
when she said that we have very talented scientists and farmers
and others contributing to creating an ecologically-based agriculture.


Pamela Ronald (UC Davis) Part 1: Sustainable agriculture

2769 タグ追加 保存
ykk 2013 年 6 月 25 日 に公開
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