| || |
Fields with Great Yields
the Dust Bowl comes back to the western United States, will
drought-resistant crops help the thirsty land? Hayley
Rutger reads the tea leaves. Illustrated by Em
The orange lights in the greenhouse
glow like artificial suns. Tobacco plants reach toward them in the
still, humid air. Their pale pink trumpet flowers and dark leaves
hide a secret. Some scientists call them chimeras, after the
mythical monster with the heads of a goat, lion, and snake; their
DNA is part tobacco, part bean, and part bacterium. The strange
genes have given the plants a superpower: drought resistance.
Scientists have devised these transgenic plants to fight the formidable foe of water
shortages, caused by climate change. These plants drink two-thirds
less water than average tobacco. Crops like canola, tomatoes,
cotton, and rice may soon share their hardiness. The balmy greenhouse
where these chimeras grow is a training ground for the global
greenhouse their descendants will inhabit, under the open sky.
As temperatures rise, many climate models predict
another Dust Bowl. This historic 1930s drought may come back to
haunt the American West in three decades or less. Rivers that cut
through the arid land like vital arteries will shrink. More rain
and less snow will fall onto the Sierra Nevada. Some precious
precipitation will evaporate too early to make it down, and states
that depend on it will suffer, unless agriculture adapts quickly.
But engineering crops takes time.
To do transgenic
plants is not. . . poof! says plant biologist Eduardo Blumwald with his strong
Argentinean accent, flicking his wrist like a magician. Blumwald
hopes his crops will come to the fields in time to battle drought
and famine. Today, today, 2008, I think there is enough food in
the world. He taps the desk with one finger. But in another ten,
fifteen, twenty years, I dont think so.
one reason post-doctoral researcher Rosa Rivero spends 10 to 11
hours a dayand sometimes weekends tooin Blumwalds lab at the
University of California, Davis. Shes examining the molecular
mechanisms that keep the tobacco going on 70 percent less water.
Many scientists have proposed methods to make water-saving plants,
but Blumwald and Rivero are the first to do it so well. Their
transgenic plants dont drop their leaves and shrivel in tough times;
they wilt a bit and perk up again when watered. Blumwalds work is
partially funded by a Davis-based biotechnology firm, Arcadia Biosciences, that is trying to validate
these results and work toward federal approval.
But some consumer advocates think these chimeras
must be caged. They say transgenic foods get scant safety testing
on the way to grocery stores, and they can sicken or even kill
laboratory animals. Biotechnology companies and some scientists
contend these concerns arent based on firm evidence. The impending
drought, on the other hand, looms as clearly as the Sierra.
Dire, drier predictions
The whole surface of the planet is warming up,
says climate scientist Richard Seager of Columbia
University's Lamont-Doherty Earth Observatory. There will be
year-to-year variability, but all under a gradual drying trend.
Seager, who has examined past North American droughts, recently
published a study on the return of
the western Dust Bowl. He studied 19 climate models, and 18 of
them agree: Drought maps depicting water shortages in the western
U.S. in yellows, oranges, and parched reds will only get redder.
For states like Arizona, Utah, New Mexico,
Nevada, and California, keeping things green is already difficult.
California, the biggest water guzzler, usually pours more than 80
percent of its water into agriculture; it used 30.5 billion gallons
for irrigation in 2000. Other southwestern states use less, but
they all depend on rivers like the Colorado. Scientists studying
the Colorado think that in two decades, it wont be able to slake
that thirst. Snow on the Sierra will melt more quickly, and that
water will gush down the slopes two weeks earlier in the spring by
2050. Some will evaporate before the water infrastructure can
collect it. A single wet winter wont alter this long-term trend,
Seager says: Its time to start planning for this.
Promoting good behavior
People have weathered droughts by altering crops
in the past, but not by using DNA chimeras. During the original
Dust Bowl, before anyone used the term gene or knew that these
little snippets of DNA control a living things biochemistry,
researchers bred more resilient and productive corn by moving pollen
between cornstalks and controlling mating. This corn survived dry
weather that often killed other varieties. Today, armies of it
cover U.S. fields.
No one toyed with DNA
directly until 1973, two decades after James Watson and Francis
Crick described its twisting ladder shape. Researchers learned that
certain proteins would snip DNA and others would stitch it together.
They handcrafted genes and put them into bacteria. Bacteria have
since become genetic engineers little helpers, because some will
infect plants, delivering the new genes. Scientists kill the
bacteria with antibiotics directly afterward, leaving added genes
that can control many of the plants traits by telling them which
proteins to build.
plants are like painters using palettes with thousands of colors.
Of all the genes out there, which ones to choose? Researchers
demonstrated in 1995 that a gene for making extra cytokininthe hormone that helps a plant retain its
leaveswould keep plants not only green during drought, but fruitful.
Leaves make the sugars and starches that plants store in their
fruits and seeds, using carbon dioxide and sunlight.
During droughts, plants naturally drop leaves and
favor roots, a strategy at odds with agriculture. Plants in the
wild just want to live on through their kids, Blumwald says. Even
if they drop eighty percent of the leaves but can make a few seeds
that will be blown away and grow somewhere, heck, thats evolution.
But he says weve bred crops that go all or nothing; they make lots
of grains or kernels, but they cant scale back in dry times.
Scientists thought that if these crops made more cytokinin and kept
their leaves, wed have amber waves of grain that could stand searing
waves of heat.
The challenge, Blumwald
says, was finding a "promoter," a second snippet of DNA that would
make the cytokinin gene really step it up during drought. The 1995
study tried a promoter that turned on the cytokinin machinery when
leaves started dying. However, this meant that even during wetter
times, old leaves would stay vivacious. Later studies found that
these leaves could steal resources from younger tissue. The lead
author of the 1995 study, plant biologist Susheng Gan of Cornell University,
believes his plants only had problems because they were given
restricted resources during the experiments. With more nutrients,
he says, the young tissue would do fine. But no one has tested his
theory. Instead of this potentially problematic promoter, Blumwald
wanted one that switched on only when drought stressed the plants.
Tiny puzzle pieces
Luckily, Blumwalds colleague and former teacher,
Shimon Gepstein from Technion, the Israel Institute of Technology,
had a promoter from a bean plant that fit the bill. Blumwald recalls
their chat: I said, I need a promoter that can do this, this, this,
and that, and he said, Hey, I have it. So I invited him to come
to my lab, and we started working. Gepstein became a coauthor of
the study, and researchers from Japan and Arizona chipped in too.
Rosa Rivero, who hails from Spain, fits
right into this international lab. She genetically engineered the
tall tobacco in the greenhouse. To describe the science, she likes
to draw pictures.
Her black marker squeaks
on the whiteboard as she makes a circle. She says its a plasmid, a
little ring of DNA found in bacteria. Bacteria can pass them off
to one another; some bacteria can pass them to plants. Rivero makes
two little tick marks on her circle, showing that shes added a
snippet of new DNA. This is the bean promoter, plus the cytokinin
gene from a bacterium. She draws an oval around the circle. The
bacterium has taken the plasmid into its body, and its ready to
deliver it to the tobacco. She sketches a beaker full of liquid,
which she says is teeming with those bacteria. Finally, she draws
a stem with flowers on the end, dipped into the liquid. The bacteria
go to work; they transform the plant.
|Slideshow: Author Hayley Rutger examines how the
UC Davis team makes drought-tolerant plants. (Click
image to launch show.) |
After Rivero adds
genes to tobacco, she takes a bit of leaf tissue and turns it into
a whole new plant, using hormones and time. This technique, called
tissue culture, has been around since the 1950s
and is used to clone plants. Rivero waits for her plants to mature,
and then she breeds them for three generations to make sure they
carry only the drought-tolerance gene. With tobacco, a generation
takes a few months. With plants like rice and cotton, it can take
two years. Blumwald was righttheres no quick poof here.
But it was worth the time. When Blumwald and
Rivero stopped watering the plants for fifteen days, the plain
tobacco never recovered. The chimeras sprang back up after drooping
slightly. When the scientists grew the plants on 30 percent of the
water they usually got, the regular tobacco produced 60 percent
fewer seeds than the engineered tobacco. They did this test outdoors
in the summer, and they plan to do it for several summers to come,
soon with different plants. For now, the tobacco is snug indoors
and out of the chill winter wind.
room behind plastic curtains, Rivero raises young tobacco in an
incubator that works like a mini-greenhouse and looks like a
refrigerator. The curtains block most of the noise from the
incubation machinery. But its muted whirr permeates the lab,
overlain by lively Spanish music from a radio. Rivero dons purple
latex gloves and square-rimmed glasses, ties back her curly brown
hair, and sets out to understand how more cytokinin makes super
tobacco. While other scientists in Blumwalds lab are starting to
engineer rice, tomatoes, and cotton, shes studying tobacco in detail.
Rivero calls tobacco a great model for
horticultural plants. It grows fast, making hundreds of tiny seeds
that look like coffee grounds and sporting large leaves. I love
them, she says. When youre working with molecular biology, you
need to get RNA and DNA and proteins, and for that you need a lot
of plant material. RNA is the molecule that translates DNAs genetic
code into proteins. Rivero and her colleagues are studying about
45,000 different bits of RNA in the tobacco to find out which genes
might play a role in drought tolerance. So far, the RNA tells them
that genes for antioxidantsbeneficial chemicals also found in healthy
foods like blueberrieswork better in the drought-resistant crops,
perhaps protecting the leaves from stress.
Photo: Hayley Rutger
|This vial, full of chlorophyll from a purified
membrane in transgenic tobacco plant cells, may contain a protein
that helps the plants resist drought. |
Rivero also studies
one important protein that a plant must have to make its own food.
The protein comes from the green membrane in the leaf that absorbs
energy from the sun. Rivero holds up a plastic tube full of emerald
liquid. Inside is the pure membrane, containing the green molecule
chlorophyll and the protein that might give transgenic plants the
advantage. Maybe this protein is the key. We dont know yet, she
Blumwald and Riveros close look at
cytokinins effect on tobacco is a valuable contribution, says Susheng
Gan. The teams work, using cytokinin to counteract stress, is not
the first at all, Gan says, but this is a good investigation. Nobody
knows exactly how cytokinin inhibits senescence [death].
Gan cautions that if Blumwalds crops overproduce
cytokinin during a drought, this could cause a harmful hormonal
imbalance. However, Blumwald says, this will not be an issue; his
promoter shuts down when cytokinin builds up.
The long way to the fields
Drought will progress as inexorably as Riveros
meticulous experiments. But at the finish line, the western U.S.
may have chimerical crops on its side. Blumwald and Rivero plan
to fortify three of California's key crops: tomatoes, cotton, and
rice. Arcadia Biosciences, Inc. plans to bring their work to
fruition, perhaps within eight years.
basically build on the research work of somebody like Dr. Blumwald.
We spend a lot of time and money validating it in the field, says
Arcadias CEO, Eric Rey. We often turn around and license the
technology to some of the big companies, who then begin the process
of putting it into their varieties. Arcadia successfully tested
the drought-resistant tobacco in the field in December. Companies
are interested but havent yet bought the license, Rey says.
It usually takes Arcadia seven years to put out
a new product. First, their researchers must test everything for
safety. They screen the DNA for unexpected changes near the newly
inserted genes. They also dig through scientific literature to see
whether the transgenic plant might cause allergies, and they feed
high doses to laboratory animals. They submit their safety reports
to the U.S. Department of Agriculture (USDA), which decides whether
the crop might harm the environment once its unleashed. The USDA
can say no to any problematic crop. Biotech companies also send
safety reports to the Food and Drug Administration (FDA), the
government agency that evaluates everything we consume from Advil
to apple juice. But no law can force biotech companies to comply
with the FDA; its voluntary. And to some consumers, voluntary
safety tests are scary.
A roll of
In nations of the
European Union, a panel of scientists must review transgenic crops,
and governments can keep them off store shelves. Theyre all monitored
for environmental effects after hitting the fields, and some are
monitored for health effects. Many U.S. consumer advocates want
similar laws. DNA chimeras, they say, are unpredictable and poorly
controlled. Jeffrey Smith, founder of the nonprofit consumer
advocacy group the Institute for Responsible Technology,
says he spoke with more than 30 scientists to write Genetic Roulette, a book warning consumers
that theyre rolling the dice at the dinner table.
Three-fourths of consumers, he says, unknowingly
eat genetically modified food. The rest knowingly consume it or
try to avoid it. No law requires it to be labeled in the U.S., but
about 73 percent of our cornfields are engineered to make their own
pesticide or to resist herbicide, according to the book. Also,
about 93 percent of our soybeans and 87 percent of our upland cotton
have patchwork DNA, Smith maintains. Soy and corn creep into all
sorts of foods, so Smith tells consumers to be careful.
In my opinion there is no scientific justification
to allow these foods out of the laboratory, he says. Theres economic
justification and political justification. He says private funding
can bias research, and this puts consumers on thin ice.
At a recent agricultural symposium in Asilomar,
California, Smith spoke more about his alarm. He presented a study
in which rats ate transgenic potatoes. Scientists later found that
the rats stomach linings looked overgrown, and possibly precancerous.
Smith also described a study where rats fed transgenic crops had
small offspring that frequently died. It might be decades before
we understand DNA well enough to make these kinds of massive changes
in a safe and predictable manner, Smith says. Because the FDA only
regulates these foods voluntarily, he believes even problematic
ones could end up in our diet.
director of regulatory affairs, Don Emlay, counters that biotech
companies would only avoid this voluntary safety check at the risk
of incurring the wrath of the FDA and food companies alike. Any
transgenic food that isnt FDA approved will hit a brick wall on the
market, he maintains. FDA officials say that to their knowledge,
all commercialized transgenic crops today have been through this
safety evaluation. The cost of developing a product is so expensive,
you want to know all this before you get too far down the road,
To address Smiths potato example,
Emlay refers to an article
by plant biologist Nina Federoff, technology advisor to the U.S.
secretary of state. Federoff says the ill effects of the transgenic
potatoes most likely came not from adding new DNA but from the
cloning process of tissue culture, which is used by both traditional
breeders and biotech companies. It can create random changes in
DNA. In the potato study, the unaltered potatoes didnt go through
tissue culture with the transgenic ones. A biotech firm would
typically catch safety problems from tissue culture by feeding its
products to laboratory animals.
The California Farm
Bureau Federation (CFBF), a nonprofit group of about 91,000
farmers and ranchers, supports research on transgenic crops. Were
in favor of exploring the technology to see what it may offer both
for farmers and consumers, says Dave Kranz, CFBF manager of media
services. Farmers sometimes express concerns about transgenic crops
pollinating other plants in the field, Kranz notes, but theyve dealt
with pollen problems since before genetic engineering came along.
However, the California Rice Commission takes a more cautious
stance. Its official statement declares: The California Rice
Commission believes there should be no field testing of GM [genetically
modified] rice. Commission officials declined to say why.
Biotech crops may be too useful to ignore as
climate change progresses, Arcadia CEO Rey believes. I think a
decade or so down the road, were going to see salt tolerance, drought
tolerance, heat tolerance, improved cold tolerance, and agriculture
that is more robust and more productive. Blumwald agrees, adding
that transgenic crops may feed burgeoning populations in the future.
People are going to the cities, people are leaving the land, but
our population continues increasing, so we need food, he says.
Researchers have a lot more experiments to do
before the descendants of a greenhouse full of chimeras fill western
fields. Only time will tell whether these unnatural plants can
save us from an unnatural disaster.
Internship: National Geographic
This may surprise you: Im really
an artistic person. I crank out poetry and piano music more easily
than I build hypotheses and experimental designs. And yet, science
calls to me. It feels more real than anything else.
I majored in biology to study what iswhat is living
and breathing and existing beyond my own imagination. In my four
undergraduate years in Florida, I fell in love with scrub jays and
sundews, gopher tortoises and gallinules. I didnt fall so hard for
field notes, t-tests, and mathematical modeling. Rather than
dissecting, solving, and untangling the natural world, I want to
be the lucky scribe who finds words for it all. Ill make my mark
in sciencenot with statistics or scalpels, but with ink.
. . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . .
B.S. (Ecology and
University of California, Santa Cruz,
As a biologist, most of
my research interests involve the genetics of pattern and color
formations in creatures and how they are influenced on an evolutionary
scale. I have participated in transgenic experiments in Lepidoptera
and micro-crustaceans, comparative high-throughput transgenic
methods, and the international standardization of cytogenic radiation
dose assessment. I am also passionate about environmental preservation
and teaching the importance of natural systems to future generations.
I believe that by teaching science through artistic media, we can
best inspire people to protect the environments that sustain them.