Genetically Modified Food Crops
Genetically Modified Food Crops
Volume 10, Issue No. 1
About This Issue...
First Questions
• How is our food grown?
• Which food plants are wild?
• What do genes do?
• What plants are safe to eat?
• Can eating genes “infect” you?
• Are all bacteria bad for plants?
• Can carrots make you see better?
How many hours did you spend growing your
food yesterday? You probably just walked to the
fridge. But a hundred years ago you might have
worked more hours in the fields than
in school. In the developing world,
that’s still the case, and food is
both scarce and expensive.
Throughout history,
people’s main concern was
producing enough food.
Civilization advanced as we
developed agriculture. For
10,000 years we bred wild plants
to produce more food with less
work. Agriculture got a boost in
the 1950s with new chemicals that
control insects, weeds, and disease.
At the same time, plant breeders
developed more productive varieties of
wheat, corn, and rice. Together, new
farm chemicals and improved crops led to
much higher
yields (amounts produced).
This increase in production was known as
the “Green Revolution”.
The Green Revolution happened at a time when
the world’s population was growing so fast that
experts predicted massive famines. But the new,
more productive crops came to the rescue. India
“Whoever could make two ears of corn, or two blades of grass
grow upon a spot of ground where only one grew before would
deserve better of Mankind, and do more essential service
for his country, than the whole race of politicians
put together.”
-The King of Brobdingnag,
Gulliver’s Travels by Jonathan
Swift, 1727
more than tripled the wheat grown on the same
amount of land. There have been localized famines
caused by drought, war, and political corruption, but
no worldwide starvation.
As we enter the 21
st century, industrialized coun-
tries are struggling with side-effects of the Green
Revolution. The overuse of agricultural chemicals is
polluting our land, wildlife, and water.
In addition, the world’s
population is
2 Genetically Modified Food Crops
Creating Better Plants....................................... 4
Weed Warriors................................................. 6
Monarch Butterfly Effect .................................. 8
Golden Rice .................................................... 10
Potato Power .................................................. 12
Profile: Florence Muringi Wambugu ................ 14
Something you can try: Growing Soybeans
and Researching Monarchs ..........................15
Volume 10, Issue No. 1
Published by:
The Biotechnology Institute
In Partnership with:
Pennsylvania Biotechnology Association
Biotechnology Industry Organization
Originally Developed by:
The Pennsylvania Biotechnology Association
The PBA Education Committee
Snavely Associates, Ltd.
Writing by:
The Writing Company,
Cathryn M. Delude and
Kenneth W. Mirvis, Ed.D.
Design by:
Snavely Associates, Ltd.
Illustrations by:
Patrick W. Britten
Science Advisor:
C. S. Prakash, Professor, Tuskeegee University
Special thanks to:
Peggy Lemaux, Ph.D., University of California, Berkeley
Wayne Parrott, Ph.D., University of Georgia
For more information:
Biotechnology Institute
1524 W. College Avenue, Suite 206
State College, PA 16801
Copyright 2000, BI. All rights reserved.
The Biotechnology
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Your World describes the application of biotechnology to
problems facing our world by bringing scientific discoveries
to life. We publish issues on different topics each fall and
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On the cover:
For thousands of years, farmers have
been crossbreeding plants to create better and healthier
crops. Today, scientists are using their understanding of DNA
to develop plants with specialized traits, ranging from disease
and pest resistance to better taste and nutrition.
The Biotechnology Institute would like to thank the
Pennsylvania Biotechnology Association, which originally
Your World.
Biotechnology & You
growing beyond the Green Revolution’s
capacity to feed it. People are destroy-
ing sensitive habitats to create more
farmland, but even so, there will not be
enough land to feed the 9 billion people
predicted by 2050.
Worse, many of the world’s poor have
never benefited from the Green Revolution
because it did not solve the underlying
problem: poverty. Many farmers can’t afford
the chemicals and improved seeds. Millions
still survive on a daily bowl of rice or potatoes.
They have no roads to
stores, no fresh produce, and no vitamin pills – and
their health suffers terribly. What can help them?
Many scientists think a new “Gene Revolu-
tion” can help both hungry humanity and
the sensitive environment. The Gene
Revolution uses biotechnology to create
genetically modified or “GM” crops.
These crops can potentially produce more
food with fewer chemicals and higher
nutritional value than traditional crops.
Scientists think they can improve even more
crops than the Green Revolution did: not only
grains, but also the legumes, vegetables, roots,
and fruits that people need for a balanced,
nutritious diet.
But some people worry that these
crops are not safe to eat and could
threaten the environment with unfore-
seen problems. They question
whether government agencies test the
products enough and whether
corporate profit motives outweigh
safety concerns. Some protesters
have destroyed research laboratories
and burned fields of GM crops.
This issue of
Your World will
help you unravel conflicting
reports about agricultural biotech-
nology. Is it safe and environmen-
tally friendly or an out-of-control
experiment? You will learn how
plants with specific traits are created,
how to weigh the pros and cons, and
how you can investigate these problems.
Your World 3
4 Genetically Modified Food Crops
1) Scientists copy a
carrot gene that
converts a pigment to
Plants live in a hostile world. Animals chew them, insects chomp them, pushy
plants surround them, and disease withers them. But plants are not
helpless. They make oils, smells, and poisons to fight back.
If you look at a leaf of a tomato plant under a microscope, you’ll see the leaf is
covered with tiny hairs. These hairs emit chemicals that act like flypaper to trap
little insects. How did this insect-fighting trait come about?
How do plants get
different traits?
2) They insert the carrot
gene into a plasmid.
3) The plasmid is
reintroduced into the
4) The Agrobacterium
transfers the carrot
gene to the cells of
tomato leaves in a
petri dish.
5) The tomato cells grow
and divide in a culture
with hormones that
encourage the cells to
become new shoots
and roots.
6) As the tiny new plants
grow, the carrot gene
converts the tomato’s
pigment into beta-
carotene, creating an
enhanced tomato.
Creating a Vitamin-Rich Tomato with a Carrot Gene
The bacterium Agrobacterium naturally infects plants. It carries some genes on a circular piece of
DNA called a
plasmid and inserts those genes into plant cells. Scientists are now able to remove the
bacterium’s genes that cause plant disease and add a gene for a desirable trait.
Photos courtesy
of Shelia Colby,
University of
California, Berkeley.
Your World 5
Discoveries Behind
Genetic Engineering
The door to genetic engineering opened when scien-
tists realized that all genes are written in the
language of DNA
. Learning to use plasmids (see
illustration) and special “cut and paste” proteins called
restriction enzymes allowed them to “edit” DNA.
Now, plant
genomics is cataloging genes that could
give plants beneficial traits, as well as genes we could
eliminate to make food safer. (See box on page 7.)
Natural Selection
Wild tomatoes may have developed these tricky leaf hairs by
chance. To reproduce, plants pollinate each other. In doing so,
they exchange
genes – the molecular instructions that produce
different traits. The offspring have a different combination from
either of their parents. Occasionally, genes undergo
(changes) during this mix. One such change made the leaf hair
cells produce the sticky insect-fighting proteins. This mutation
gave that plant an edge over others, so it passed its insect-
resistance on to new generations.
Selective Breeding
Along came the age of farming, and people noticed the insect-
resistant tomato. They selected it to pollinate other tomatoes,
such as those with bigger fruits. To understand selective breed-
ing, imagine that a gene is a book in a library. Different toma-
toes have different versions of certain books. One plant may
have a book for the insect-trapping flypaper. Another plant may
have a book that makes big fruits. If a
farmer cross-pollinates these two
plants, eventually one offspring
might combine both traits. But
genes don’t mix individually;
they come “linked” with other
books on their shelves. The
big fruit book may come linked
to a sour fruit book. Getting
rid of that sour book might take
generations of selective breed-
ing, if it could be done at all.
Selective breeding has given us a
huge variety of plants. Over time, cultivated
varieties have little similarity to the original wild
plant. For example, early Native Americans
cultivated corn from a wild grass called
teosinte. Carrots were yellow until a
mutation created an orange one in the
1700s. Two thousand years ago a single gene mutation in a
peach produced a nectarine. Observant farmers selected these
pleasing surprises and bred them.
Hybridizing Plants
Selective breeding has limitations. You can only breed
tomatoes with closely related plants. What if you want a
tomato with a trait found in a distant relative? Wild tomatoes,
which are like little berries, can fight off a soil bug that attacks
the roots, but many wild varieties can’t pollinate modern
tomatoes. Scientists broke the pollination barrier by combin-
ing their germ cells and nurturing them in a laboratory tissue
culture. They produced a
hybrid (mixed) tomato with the
ability to repel soil bugs.
Inducing Mutations
Cross-pollinating and
hybridizing depend on natural
variations, and plant breeders
search the world for useful traits.
To entice more variations than
nature provides, scientists zap seeds
with radiation and chemicals.
Occasionally this method produces a
desirable variety, such as a bean that
grows as a bush rather than a vine.
Genetic Engineering
All these methods give us some control over plant breeding,
but they are time-consuming, trial-and-error processes. Since the
1980s, genetic sciences have made plant breeding more quick
and precise – and expanded its reach.
Genomics (the study of an
organism’s entire genetic instructions) is identifying genes that
produce specific traits. Before, scientists didn’t know which
book gave the tomato leaf its sticky compound that traps insects.
Now, they can pinpoint the exact book for the flypaper goo.
They can pick that book off the shelf, copy it, and put it in other
plants. In this way, they make a
genetically modified plant.
Scientists can borrow books from unrelated species to get traits
like disease resistance, faster growth, better flavor or nutrition,
or longer shelf life.
For example, tomatoes have a pigment that gives them their
bright red color and special flavor. Carrots produce a protein
that could turn that pigment into
beta-carotene, which our
body turns into vitamin A. The illustration on page 4 shows
how scientists used the “natural” genetic engineer, a bacterium
Agrobacterium, to modify a plant. Another method coats
a tiny gold pellet with genes and shoots it into plant cells that
then grow into plants.
y cell of a plant,
and we degrade them we eat them.
are only affected by the
proteins the genes have already
made in the plants we eat.
Career Connection: Plant Breeder:
Develop new plant varieties with needed traits.
Photo courtesy of Scott Camazine, Penn State University, Department of Entomology Think
about it
Is genetic engineering a
logical continuation of the
way farmers have been
modifying food for
centuries? Or is it an
entirely new – and
perhaps risky – process?
6 Genetically Modified Food Crops
Some of the first GM crops to hit the fields are
popular with farmers but controversial with some
people. These crops are engineered to withstand
herbicides that are sprayed on fields to kill weeds.
Weeds can take over a field, and keeping them out takes
backbreaking work. In Africa, most farmers are women, and
they spend half their time weeding! Many farmers spray
herbicide to kill specific weeds at different times. (“Herb”
mean plant and “cide” means kill, as in homi-
cide.) In Africa, some weeds are parasites
that can’t be sprayed without destroying the
crop. Where herbicides can be used, weeds
can become resistant to them, so farmers
need ever-stronger and more diverse chemicals
to kill them. But many herbicides harm animals
and insects, and they last a long time in the
Scientists developed less toxic herbicides to
reduce these risks. One such chemical is
glyphosate, which is marketed as Roundup®.
Glyphosate kills green plants by shutting down the
production of essential amino acids. Insects and
animals get these compounds in their food, but
plants have to make them. To do so, a molecular “key” fits
into a protein “lock,” turning on an essential amino acid
“machine.” Glyphosate mimics the key, slips into the lock, and
jams it so the machine can’t start. The plant starves to death!
Animals don’t have that molecular lock because we don’t need
the machine, so glyphosate doesn’t affect us. It also breaks
down quickly and doesn’t stay in the environment.
If farmers sprayed glyphosate on their fields, it would kill
both weeds and crops. Thus, scientists made crops that
withstand this herbicide. They added a gene to produce a
slightly different lock. The mimic key can’t fit it, but the plant’s
own key can. The essential amino acid machine keeps
working, so the crops survive while the weeds die. “Roundup
®” crops also allow farmers to kill parasitic weeds. The
new gene doesn’t change the crop plant in any other way.
Before, farmers only had the option of
hoeing or plowing the fields to kill weeds
before planting. This practice causes soil
erosion and water pollution. With herbi-
cide-resistant crops, farmers no longer have
to till, saving them work and money. Zero
tillage also helps preserve the soil and water.
Farmers in the United States adopted GM
seeds for crops that traditionally need a lot of
herbicides. In just four years since their
introduction, more than half of the US
soybean crops grew from GM seeds. Did you
know you eat soybeans all the time? Look at
the labels on your snack foods!
about it!
What could happen if no
farmers used herbicides?
Are herbicide-resistant
crops good or bad for the
environment? Make a
chart of the pros and cons!
Should we use them?
How did scientists design an
herbicide that affects green plants
but not animals?
Risks and Benefits
Soon, critics questioned the
wisdom of GM crops. They
might be convenient for farmers,
but are they safe to eat? A GM
plant has a tiny change in the
protein lock that our bodies just
digest like any other protein.
Glyphosate itself is less toxic to
us than table salt. However, the
spray contains other ingredients
that may pose risks to fish and
wildlife if used irresponsibly –
and to people who get the spray
on them. Still, it is much less
toxic than other herbicides.
Also, farmers spray it before the
edible parts of the plants form,
so it isn’t on the food we eat.
Another concern is whether
herbicide-resistant crops will
lead to “superweeds.” Could the
crops pollinate weeds and give
them herbicide resistance?
Would these resistant weeds
spread out of control like the
invasive kudzu vine in the
south? Scientists began
studying this possibility when
developing herbicide-tolerant
crops through conventional
A herbicide-resistant crop can only
pollinate a closely related weed. The Western
Hemisphere has no wild relatives for soy-
beans, so herbicide-resistant weeds seem
unlikely in this case. In the Eastern Hemi-
sphere, the soybean does have weedy
relatives that could get the herbicide-resistant
gene. But in the wild, no one sprays herbi-
cides, so herbicide resistance wouldn’t be an
advantage and the weed might not take over
in nature. In the soybean field, farmers could
use other herbicides to kill the weed, since it
would only resist glyphosate. U.S. regulatory
agencies are closely monitoring fields to make
sure herbicide-resistant weeds are destroyed if
they appear.
Career Connection: Field Researcher:
Expand upon laboratory research by testing in “real
world conditions.”
Food Safety
Food safety is no laughing matter. Every year, hundreds of
people die from food poisoning and many more are
sickened by bacteria on food. Likewise, the green parts of
potatoes contain a toxin (glycoalkaloid), which breeders
monitor before they release the potato seed.
U.S. regulatory agencies test produce for
leftover chemicals (residues), and they also test
GM crops. People are concerned that GM goods
could create new, unknown food allergies. Companies
test the introduced gene for allergic properties and they
must label a food if the gene comes from a known allergen
such as nuts or wheat. Fungus and molds on foods cause
health risks, and they are more common on organic crops
that don’t use fungicides to kill them. A mold that grows on
corn and peanuts produces the cancer-causing chemical
aflatoxin and can cause
a whole crop to
be rejected.
Peanuts can cause deadly allergic reactions.
Scientists have identified three genes that code for
the allergic proteins. They are trying to deactivate
these genes to make a non-allergenic peanut.
Your World 7
crops have a gene that lets
them bypass the glyphosate
road block. They can still make
the amino acids they need to live.
8 Genetically Modified Food Crops
Bt crops carry a gene from a bacterium that kills
insects. Already Bt crops have eliminated millions
of gallons of pesticides, especially in cotton. Then
reports that Bt corn kills monarch butterflies set off
tornadoes of concern.
Decades ago, farmers discovered that a soil bacterium called
Bacillus thuringiensis (Bt) infects and kills the caterpillars that eat
their crops. The bacterium produces a protein that is harmless –
until it turns toxic in the caterpillar’s stomach. There, an enzyme
cuts the Bt protein into pieces that lock into a special
(protein “lock)” in the caterpillar gut. This locking action
destroys the gut and kills the caterpillar. Adult butterflies – and
other insects and animals – don’t have any “locks” for the Bt
toxin. Bt doesn’t harm wildlife the way traditional pesticide
sprays do. In fact, organic farmers have relied on this natural
biological pesticide for years.
Scientists inserted the gene for the Bt protein into crops that
are frequently destroyed by caterpillars. The plants produce the
Bt protein in their leaves. When the caterpillars eat the leaves,
they die – without pesticide sprays.
y cornstalks
battle wind, hail, and rainstorms.”
CornCam — www.iowafarmer
“Farming looks mighty
easy when your plow is a
pencil, and you’re a
thousand miles from the
corn field.”
-Dwight D. Eisenhower
The Beautiful Monarch
Monarch butterflies begin their life cycle as caterpillars (larvae).
The adults drink only the nectar of milkweeds, and they lay their
eggs on the milkweed’s leaves. Monarchs migrate far and wide
throughout the United States, but all return to one small, unique
area in Mexico for winter. Recently, part of that habitat has been
destroyed, and pesticide sprays throughout the migration path
have further reduced the monarch’s numbers. Naturally, people
are concerned about new threats to the butterfly’s well being.
Several researchers planned a simple laboratory experiment to
see what effect Bt corn had on monarchs. They grew two types of
corn: a “control” corn and a Bt variety. Then they dusted the corn
pollen on the leaves of milkweeds. Scientists put these leaves in
petri dishes with monarch caterpillars, which ate the pollen. The
larvae that ate Bt pollen died within days, while the other larvae
lived. A press release of this study caused immediate concern. Bt
corn was killing the beloved “Bambi” of the insect world!
Of course, life in the fields is not so simple. Other researchers
are studying whether monarchs are actually harmed by the Bt
corn grown in their migration path. Do the caterpillars eat
significant amounts of corn pollen in the wild? Does Bt harm
adult butterflies? Do milkweeds grow near cornfields? Does the
corn pollen drift to the milkweeds in harmful amounts? Does the
border of non-Bt corn that surrounds many Bt cornfields
(see next page) keep Bt pollen from drifting beyond it?
Does corn pollen stick to the waxy milkweed leaves?
Does corn pollinate at the same time that larvae
hatch, and how does this timing vary from
region to region? Finally, how does Bt corn
compare to the alternative – spraying
non-selective pesticides over fields? Do
pesticide sprays drift farther than corn
pollen? How do
these sprays affect
wildlife, human health,
and the environment?
The Environmental Protection
Agency called for more studies to answer such
questions. (For links on these studies – and
to design one yourself – see page 15.)
Can insect-resistant corn
harm butterflies?
Your World 9
“Natural medicines” such as Echinacea aren’t tested
unless it’s proven that one causes serious harm.
Likewise, traditional foods aren’t government regulated,
even though they can contain known toxins or aller-
gens. GM crops were regulated from the beginning,
and these regulations were strengthened in 2000.
The Environmental Protection Agency (EPA) requires
permits and testing for pest- and herbicide-resistant
crops and is researching the potential problem of
superweeds and superbugs. The Food and
Drug Administration (FDA)’s position is
“Product, not process.” It judges a plant’s
nutrients, not the process used to make it
(genetic engineering). Companies must
submit detailed safety information to the FDA
before introducing a new GM food. The
Department of Agriculture (USDA) oversees
field tests of GM crops.
Career Connection: Entomologist:
Study the insects that destroy crops and those that
protect crops and delight our eyes.
about itabout it!
Should a GM food be
treated differently
because it was made
using genetic engi-
Refuges from Superbugs
You may know that bacteria
can become resistant to an antibiotic medi-
cine. Bacteria mutate so rapidly that one
offspring might survive an antibiotic attack.
That offspring will thrive and produce a
new strain of resistant bugs. The same thing
happens with bugs in the field. Eventually,
insects become resistant to pesticides – even to
Bt crops. To delay that day, farmers must plant
sections of non-Bt crops in their fields. These
non-Bt sections are called
refuges (safe places).
Bt-resistance won’t give insects in the refuge
any advantage over non-resistant bugs. Thus,
non-resistant bugs survive. When they mate
with resistant insects, the offspring have less resistance.
Researchers are testing what size and shape refuges should
be. Farmers can also rotate crops to interrupt the
multi-year life cycle of insects and they could use
Bt crops only on a “prescription” when the
bugs are thriving.
Corn Borer
Photo provided by USDA
10 Genetically Modified Food Crops
The bright orange of carrots comes from
beta-carotene, which forms vitamin A in our
bodies. Yet 250 million people suffer from
vitamin A deficiency. Each year a half million
children become blind from lack of vitamin A
and over half of these die within months.
Ideally, everyone would have a varied diet with lots
of produce that supplied ample vitamin A and other
nutrients. Better nutrition could prevent up to two
million deaths in children under the age of four each
year. But that requires more prosperity for much of the
world – something that’s a long way off. Nearly half the
world’s population survives on a daily bowl of white
rice, which contains no vitamin A. Making rice more
nutritious could improve people’s lives tremendously.
Nutritious Genes
A team of researchers decided to try creating a rice
that contains beta-carotene (the compound we convert
to vitamin A). They were inspired by the bright yellow
daffodil. How did it produce beta-carotene? They
found that several daffodil enzymes manufacture beta-
carotene from other molecules. Rice has those other
molecules, but it doesn’t produce the enzymes to
rearrange them into beta-carotene in its kernel. Could
they give rice the genes for those enzymes and get
them to work together? Previous researchers had
inserted several genes that worked individually to
make separate products. No one had successfully
inserted a group of genes that had to work in
sync to make one product.
They tried putting the genes in a gene
gun and shooting them into rice cells.
That didn’t work, so they put two genes
in one
Agrobacterium and another
gene in another
Both bacteria “infected” the rice
cells, inserted the new genes,
and soon the lab grew rice plants
carrying all three genes. It was
easy to see that the genes worked
because of the kernels’ golden glow.
A bowl of this “golden rice” provides
enough vitamin A to keep a person healthy.
Meanwhile, research-
ers are working on a
related nutritional
problem. White rice also
contains very little
useable iron, and without iron, children
don’t grow or learn well. Iron deficiency
causes 40 million mothers to have prema-
ture and low weight babies. Many of these
mothers and babies die of anemia. The
solution also involves several genes from several
sources: a fungus, another kind of rice, and a
green bean. These genes produce proteins in the
rice kernel that help the human body absorb and store
iron. Again, they are using
Agrobacterium to get the
genes into rice.
Someday, researchers may crossbreed the rice plant that
makes beta-carotene with one that makes iron to produce a
hybrid that makes both essential nutrients.
ch team worked ten years on golden rice.
They are working out legal issues so they can donate
this rice to farmers in developing countries.
How are scientists
modifying rice
through genetic
Photo courtesy of Peter Beyer, Institut Für Biologie II, Freiburg, Germany
Career Connection: Greenhouse Technician:
Grow new varieties from tissue cultures and conduct
experiments on plant growth and pest/disease resistance.
Your World 11
More Rice in the Bowl
Golden rice may be more nutritious, but soon there simply
may not be enough rice of any kind to feed the growing popula-
tions in Asia. These countries will need to grow 40% more rice by
the year 2020. Earlier, scientists increased a rice crop’s productiv-
ity through traditional crossbreeding. They bred a rice with a
sturdier stalk that didn’t flop down into the waters of the rice
paddy and rot. This simple change increased yield by reducing
waste. But for more dramatic improvements, scientists are
turning to genetic engineering.
Some researchers seek to reduce waste even more by develop-
ing insect-resistant rice using variations of the Bt gene. Insects
currently ruin about 25 million tons of rice each year, both as the
plants are growing and after the rice is harvested. Reducing these
yearly losses could feed 120 million people!
Another project boosts the productivity of rice by revving up
its photosynthesis. Rice belongs to an old line of plants that
developed when our atmosphere had more carbon dioxide
) than today. Newer plants, such as corn, evolved when the
atmosphere had less CO
. They use CO
more efficiently by
using a kind of “CO
pump”. Researchers put the genes for the
“pump” proteins in rice. That rice grew faster and lusher,
producing up to 35% more grain. Many other foods – potatoes,
wheat, oats – also use CO
inefficiently. Tomorrow’s scientists
may be able to boost their yield to help feed the extra billions
who will soon share the earth.
Some people say GM crops can benefit
poor, small farmers because they won’t
need chemicals or equipment to improve
their farms. Others say farmers will
become dependent on huge international
seed companies. Follow this debate in
the news!
More Food
Per Acre
We will need to double the food
we grow to feed the world in
2050, but we can’t double the
amount of farmland. There just
isn’t that much arable land left,
and we also want to preserve
natural habitats and biodiversity.
Over the past 50 years, more
productive crops have spared
millions of acres of wilder-
ness around the world from
becoming farms. GM
plants may help increase
food production so that we can
produce the food we need
without taking up more land.
We may have plants that need
less water for irrigation so we
preserve our limited water
supplies. Someday, crops may
grow where it is too dry, too
cold, or too salty for anything to
grow now.
Photo provided by National Geographic Society
Terraced rice fields in Bali, Indonesia.
12 Genetically Modified Food Crops
You may have cried when you got your first vaccine
shots, but at least you haven’t died from the horrible
childhood diseases they
prevent. Millions of
children around
the world can’t
get vaccines, so
they still die of
Many poor countries can’t afford vaccines or can’t get them to
remote villages. Clinics often can’t refrigerate the vaccines or
sterilize needles. These problems make safeguarding millions of
children extremely difficult. In addition, most vaccines are made
from the infectious organism that causes the disease. Every once
in a while such vaccines can cause harmful side effects, even the
disease they are supposed to prevent.
In 1991 the World Health Organization challenged scientists to
create a simpler, safer, cheaper way to vaccinate children. Some
scientists began to brainstorm about plants. Since plants naturally
make a number of different compounds, could they be repro-
grammed to make edible vaccines?
Potato Vaccines
Researchers tried making a cholera vaccine using plants.
Cholera is a bacterial disease that causes deadly diarrhea. It
spreads rapidly where people don’t have clean water and it kills
two to three million children each year. Research-
ers pinpointed part of the cholera bacterium
that the human immune system can
recognize, so it could be used as a
vaccine. Scientists found the genes
that make that bacterial part. After
some trial and error, they put
those genes into potatoes to
How could
plants improve
medicine and
Organic Farming
Some people believe that GM crops are unnatural.
Some believe we should expand sustainable organic
farming instead of Green and
Gene Revolution technologies.
Organic farmers battle insects
by rotating crops and using
friendly ladybugs. They mulch
and weed instead of
spraying herbicides and
they use manure instead of
synthetic fertilizers. Organic
farming is appealing, but can it feed the
world? Most organic farms are small and
can’t mass produce food for huge popula-
tions. In general, organic farming doesn’t
produce comparable yields per acre, so it
uses more land and costs more. Also, using
uncomposted manure can increase the
danger of bacterial contamination in food.
Many farmers in the developing world are
“organic”, but not by choice. They are
subsistence farmers with few resources, who
can barely grow enough food for themselves.
Often, they can’t afford animals that produce
manure for fertilizer. They have no means to
fight the plant diseases and pests that destroy their
crops. GM crops might be useful tools for them.
Your World 13
about it
• Is any agriculture
production system
truly “natural”?
• Would third world
farmers welcome GM
crops that increase
yield and nutritional
value without
• If it is immoral to make
GM crops, what about
not producing crops
that could prevent
starvation or disease?
turn potatoes into a handy vaccine. Potatoes grow in many areas
of great health need, and they can withstand long shipping and
storage. But there is a snag. People don’t eat raw potatoes. So
scientists cooked them and found that some of the vaccine still
survives. When people ate these cooked potatoes, their bodies
made some of the antibodies that can protect them from cholera.
Imagine getting your vaccines and boosters from potatoes or
some other food instead of painful shots! But that’s still a ways off.
With the cholera vaccine, researchers need to adjust the dose in
each bite and find ways to package them. Of course, people will
get their vaccine bits from nurses and clinics, not from the
supermarket. Ideally, edible vaccines wouldn’t spoil, which would
cut the cost and difficulty of delivering them in the developing
world. They’d be more pleasant, too.
Fries for the Overfed
In industrialized countries, most people don’t suffer from too
little food. They suffer from too much. Obesity is a major health
problem even for children. We all know that we should avoid
greasy french fries and sugary sodas, but it’s hard! If we can’t take
the junk food away from people, maybe we can take the “junk”
out of food – but keep the taste in.
Again, scientists are looking at the potato. When it’s fried, oil
replaces the water in the potato. But the starchier the potato, the
less oil it soaks up. Restaurants pay a premium price for high starch
potatoes because they make crisper, less greasy fries. Scientists are
trying to develop potatoes with even more starch so they will soak
up even less oil.
Another way to make a healthier fry
is to make healthier oil. Scien-
tists have already modified
plants like soybean and
canola to produce a less
saturated, more healthy fat. Future plants may make even healthier
oils that actually strip away fatty deposits from your arteries.
What about that soda with your fries? Scientists are working
on that, too. They are modifying the sugar beet to produce an
enzyme that changes sugar (sucrose) to fructan. Fructan tastes
like sugar, but we don’t digest fructan so it adds no calories. They
have also cloned the gene for a protein in an African plant that
tastes a thousand times sweeter than sugar! We could get the
same sweetness with a thousand times less sweetener.
Other Branches
These are just a few examples of how plants can be engineered
to make medicines and healthier foods. In addition to food crops,
scientists are working on projects ranging from making more
brilliant flowers that bloom longer to trees that can clean up
mercury contamination in soil. Some of the methods used for
genetic engineering can also be used to preserve endangered plant
species that hold many valuable secrets.
Career Connection: Food Scientist:
Study ways to turn plant products into safe,
nutritious foods.
Florence Muringi Wambugu
Florence Muringi Wambugu
grew up on a small subsis-
tence farm in Africa. Now she
directs the African Center of
the International Service for
the Acquisition of Agri-
Biotech Applications.
hen Florence was a child,
the farm provided her
family’s entire income
and all their food. “My mother
always tried to grow more food,”
Florence recalls. “She looked for better seeds. She
couldn’t afford chemicals, so she used ash to control
insects. It was not easy, but she made enough money
to send all of us to school. My mother was the
inspiration for my career in agricultural research.”
Florence wanted to use science to help communi-
ties like her own. She studied botany at the University
of Nairobi in Kenya. She traveled to America for a
Master’s in plant pathology at North Dakota State
University and then to England for a Ph.D. in virology
from the University of Bath. Back in the U.S., she
conducted post-doctoral research at Monsanto.
All the while, her heart never left her village. Her
research focused on the sweet potato and the viral
diseases that kill it. “When we were young, there was
not always enough food. We grew many crops, but
we depended on sweet potatoes. They were always
there when there was nothing else to eat. But in the
tropics, sweet potato crops produce only a third as
many potatoes as they do in Asia. A virus kills up to
80% of the crops in Africa. A family’s very survival is
threatened when viruses strike their crops. I wanted
to solve a national problem: creating a sweet potato
with virus resistance.”
Fighting viruses in crops is something only
biotechnology can do. Pesticides, herbicides, and
fungicides can’t control plant viruses. Researchers
have to find the genes that produce proteins that
keep a virus from replicating. Florence devoted ten
years to transferring such genes into sweet potatoes
and preparing the plants for field trials in Kenya.
During that time, she worked at the Kenya Agricul-
tural Research Institute and at Monsanto in St. Louis
with other Kenyan scientists.
Florence now directs the African Center of the
International Service for the Acquisition of Agri-
biotech Applications (ISAAA), introducing agricul-
tural technology to benefit Africans. Virus-resistant
sweet potatoes are just one of the genetically modified
crops Florence thinks can help Africa. For example,
GM seeds for a more productive banana cost more,
but farmers are buying them. “One woman never
sold more than five bunches of bananas in a day. She
sold 48 bunches of the new banana. Now she has
expanded her kitchen and banana orchard and
increased her food and farming income.”
“People in wealthy countries criticize GM crops,”
Florence says. “They have no real need for them –
nobody is hungry. But there is real need in Africa. A
hungry person is not a myth. It’s a person I know.”
Courtesy of ISAAA AfriCenter
14 Genetically Modified Food Crops
ence Inspects banana plants in Kenya.
Designing a Monarch/Bt Corn Study
You’re concerned about monarch butterflies, so you want to
design a field study to test whether Bt corn impacts monarchs in
the wild. Your class will break up into groups and each group will
select a question to study.
1) Do larvae eat corn pollen in the wild?
2) Does corn pollen drift from the field to milkweeds?
3) How much Bt corn
pollen does it take to
harm the larvae?
4) Does corn pollinate at
the same time that
larvae hatch through-
out the monarch’s
migration path?
5) How do Bt corn pollen
and pesticide sprays
compare regarding the
impact on monarchs
and other insects and
Before you design your
study, you need to know more about monarchs. Gather informa-
tion in the library; the Monarch Watch web site (www.monarch;;; and Questionable Conclusions From
Latest Monarch Study: http//
• Research What is the monarch life cycle, timing of
reproduction, and migration path?
• State the Inquiry Which question/s will your group
• Form a Hypothesis What results do you expect to find?
• Design a Procedure How will you conduct your field study?
• Conclusion Describe what scientists could conclude from
the results.
• Extensions Study butterflies yourself. Order a butterfly kit
from Monarch Watch. Take a virtual tour of plant transfor-
Growing Soybeans and
Researching Monarchs
Growing Soybeans
Can you tell the difference between a genetically modified
plant and a traditional one? Do the seeds look different? Do they
germinate and develop differently? Do they respond differently to
their environment?
Find out by using
an activity kit
provided to your
teacher. You will
compare traditional
soybeans and GM
“Roundup Ready
soybean seeds that
have been geneti-
cally modified to
withstand the glyphosate in the herbicide Roundup
®. (See the
“Weed Warriors” article on pages 6-7.) Here’s what you will do:
Day 1: Plant four GM soybean seeds in one flowerpot and four
traditional soybean seeds in a second flowerpot. Give
them plenty of water and light, and record your observa-
tions daily.
Day 5: Sprinkle the pots with weed seeds and continue
watering and observing the seedlings.
Day 15: Apply the herbicide Roundup
® to all the soybeans and
weeds in each pot.
Day 16: Observe and compare the results. Which plants are
dying and which are still healthy? How can you explain
the results?
Career Connection: Biotechnology
Help people understand new scientific discoveries.
Your World 15
Roundup ® and Roundup Ready® are trademarks of Monsanto Corporation. The activity kit
was developed for the Biotechnology Institute by Neo/SCI Corporation. All Rights Reserved.
Harvest Your Knowledge
The Biotechnology Institute
thanks our founding sponsors,
whose generous support has
launched the Institute and
made this issue of Your World
possible. For more information
on the Institute, to look at or
order previous issues, or to let
us know your thoughts, please
visit our web site at The
next issue of Your World will
address Genomics.
Sow Your Garden
Ag Biotech Info-net:
Church of England Statement of Genetically Modified Foods,
April 1999:
Food Safety:
Grocery Manufactures of America:
Peggy G. Lemaux, “A Tomato is a Tomato, Or Is It? Consumer Acceptance of
Genetically Engineered Food,”
New York Times Genetically Modified Foods:
Time Magazine, July 31, 2000: Grains of Hope:
Union of Concerned Scientists:
USDA: Science in your shopping cart: and
Winding Your Way Through DNA: Green Gene:
We must not hope to be mowers,
And to gather ripe, golden ears,
Unless we have first been sowers,
And watered the furrows with tears.
It is not just as we take it,
This mystical world of ours,
Life’s field will yield as we make it,
A harvest of thorns or of flowers.
-Johann Wolfgang von Goethe
The direction of plant science can
profoundly change our approach to
the world’s food, medical, and
environmental problems. Will we
make of this science a “harvest of
thorns or of flowers”? People have
a responsibility to keep informed
about these rapid advances so
they can guide the outcome of
scientific research. You
probably now understand
more about these complex
issues than most adults.
Go and educate your elders!
Created Date1/3/2001 11:12:09 AM