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PHOTO BY DON MANNING
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Illinois Research
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Volume 1, Number 1, 1997
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genetic
journey
“We are witnesses to and
participants in a watershed
of human history...
in all of this there are
promises to ponder, both
realistic and inflated, and
dangers to consider, both
real and imagined. We
have already entered
the doorway of the
Gene Future.”
Thomas F. Lee, Gene Future
By Doug Peterson
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I
n 1878, a young horticulturist stopped at a monastery to see the
gardens cultivated by a modest Moravian monk named Gregor
Mendel. When the horticulturist asked the monk how he had man-
aged to “reshape” several beds of green peas to reach certain heights
and display certain characteristics, Mendel reportedly said, “It is just a
little trick, but there is a long story connected with it which would take
too long to tell.”
A long story, indeed. As it came to be,
Mendel’s “little tricks” with green peas
established several revolutionary laws of
heredity and earned him the title of “the
father of genetics.” Mendel had presented
a paper about his hybrid work on peas in
1865, but his research went unnoticed
until 1900—after the monk had died.
The history of genetics has not only
been a long story. It has been a long
journey, tracing back thousands of years.
Mendel’s work was one of the major
milestones along this path, and it set the
stage for dramatic
plant-breeding
successes in the
twentieth century.
Today, the path for this genetic
journey is something of a superhighway,
as research progresses at accelerating
speed. In agriculture, revolutionary new
technologies now allow the direct
transfer of genes from one organism to
another—what people normally think of
when they hear the term “genetic engineering.” For instance, Bt corn has been
genetically engineered to contain a toxin
made by Bacillus thuringiensis (Bt), a
bacterium that is nontoxic to humans
but controls European corn borers.
“Out in the field, that’s all
that people want
to talk to
me about,” says University of Illinois entomologist Kevin Steffey.
If the gene revolution fulfills its
promises in agriculture, it couldn’t be
better timed. Jerry Nelson, a U of I agricultural economist, says that yields on
farmers’ fields and research plots began
to stagnate in the late 1980s. In fact, by
the early 1990s, the rate of growth in
agricultural productivity fell for the first
time below the rate of growth in the
worldwide demand for some important
food crops.
Pressures on the food supply are
coming from both poverty and affluence,
Nelson says. The poorest people tend to
be concentrated on fragile land, straining
the limits of soil and water. Meanwhile,
a rising middle class throughout the
world, particularly in Asia, is increasing
the demand for meat. (See Perspectives,
p. 2). As an added twist to the scenario,
Americans are putting greater emphasis
on a diet that meets specific qualities—
food higher in nutrition, lower in fat,
and increasingly safe.
To meet these varied demands, the
focus of genetic research is not just about
boosting yields. It’s also about controlling insects and diseases and boosting
food’s nutritional value. At the U of I,
genetic research on plants and animals
reflects this broad focus, as the following
five stories demonstrate.
These stories describe just a part of
the genetic work going on in three
critical areas—soybeans, corn, and
animals. And at the heart of each
story are those tightly coiled strands
of DNA—the genes that make up chromosomes and that hold the blueprints for genetic traits.
“Genes are the central core of
plant and animal research,” says
Ted Hymowitz, U of I plant
geneticist. “It all begins
with the DNA.”
Harris Lewin, professor of
animal sciences, reviews an
autoradiogram with student,
PHOTO BY DAVID RIECKS
Shelley Fisher. Lewin found a
link between certain genes
and the resistance of cows to
the Bovine Leukemia Virus.
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“Genes are the central core of plant and animal research.
It all begins with the DNA.”
mapping
the
animal genome
arris Lewin’s lifelong fascination with farming began while
growing up in the most urban
of locales—New York City. He was
probably one of the few five-year-olds in
the city to get up at 5:30 on Saturday
mornings to watch Modern Farmer on
television. This same fascination drives
Lewin’s research today as he works to
map those genes that control important
traits for cattle.
Lewin, a University of Illinois professor of animal science and director of
the university’s Biotechnology Center, is
one of the leaders behind the National
Animal Genome Research Program, a
less-publicized counterpart to the
Human Genome Project. The project is
striving to develop genome maps for the
most important agricultural animal
species—pigs, cattle, poultry, and sheep.
“Think of a gene map in the same
way as an ordinary road map, depicting
a very complex highway system composed of many different ‘roads’ that intersect and cross each other,” Lewin
H
says. “A gene map shows you the signposts along the way, telling your location
on a chromosome.”
Researchers look for signposts—
called “gene markers”—that will direct
them to the genes controlling important
traits, such as disease resistance. Cattle
have the same number of chromosomes,
and the genes are ordered in the same
way on those chromosomes. Scientists
are looking for differences in the genes
themselves that give one cow an advantage over another.
Lewin has worked extensively on the
BoLA system of genes—the master genes
of the mammalian immune system. He
found a link between certain BoLA genes
and the resistance of cows to the Bovine
Leukemia Virus (BLV). About 50 percent
of the dairy cows in the United States are
infected with BLV, and about 30 percent
of the infected cows develop “persistent
lymphocytosis”—a serious ailment that
reduces milk production.
By identifying the BoLA genes that
offer resistance to persistent lymphocytosis, producers can breed for that disease-resistant quality, saving millions of
dollars nationwide.
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According to Lewin, global food production will be a major issue in the next
century. But he believes that significant
increases in the quantity and quality of
plant and animal products will require
an understanding of the genes behind
economically important traits.
To further such genetic research, the
Biotechnology Center, working closely
with the College of Agricultural, Consumer and Environmental Sciences and
other colleges on campus, is developing
plans for a Center for Comparative
Genome Science. The center will feature
a large lab with several automated
“DNA sequencers” for researchers
studying organisms with agricultural
significance—plants, animals, and even
microbial life. This technology was first
used in agriculture earlier in the 1990s,
and the first genetically engineered plant
species are just now becoming available.
“Equipment in the new center will do
the work much faster,” Lewin says.
“That’s why there is so much
excitement.”
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developing
thoroughbred corn
stalking the
wild soybean
or nearly 20 years, Ted Hymowitz has traveled across the world in
search of genetic treasure. And along the way, he has faced serious
injuries, foreign prisons, policemen wielding machine guns, and termite soup—not to mention the sand traps and mudholes that have stymied
his vehicles.
Hymowitz, a U of I plant geneticist, has been searching for distant relatives of the soybean—wild species with a wealth of genetic traits that offer
promise to soybean breeders. It’s a hunt that has taken him to over one
hundred countries, including such far-flung locations as Fiji, Tonga, Papua
New Guinea, Taiwan, Japan, Indonesia, and most recently the outback of
Australia.
“The whole idea behind the project is that wild relatives of cultivated
plants have much to offer in terms of genetic diversity,” Hymowitz says.
“Wild plants have developed under completely different conditions than
cultivated plants, so you can expect genetic differences.”
Some of these genetic differences offer hope of disease and insect resistance—as long as the traits can be passed on to the cultivated soybean.
Since 1976, Hymowitz and his colleagues have discovered and collected
ten new wild perennial relatives of the soybean, bringing the total to sixteen. They also have discovered that among the sixteen wild species, there is
genetic resistance to the most economically damaging diseases of the soybean, including major ones such as soybean cyst nematode, soybean rust,
and white mold.
The research team is now taking the next big step—determining whether
these traits can be passed on to the cultivated soybean plant. The first results should be back within a year, Hymowitz says.
Reaching this step, however, has taken a lot of vigorous, basic research.
“To make use of this wild material, someone has to go out and get it,”
he says. “And it’s not found in London, Rome, or Paris. First, we have to
get to know the environment of the plants we are looking for. We must
know the ecology and do a lot of map work so we can narrow the search.
And we must build on experience.”
Put an emphasis on the word “experience.” Hymowitz has had his
share of singular experiences, including the time he fell down a mountainside in Vanuatu (formerly New Hebrides), injuring his arm and leg.
Three days later, when he finally reached a hospital, gangrene had set in,
but an Australian doctor managed to save his arm and leg. After being discharged from the hospital, with his leg still swollen, he immediately rented
a car and returned to the hunt.
Hymowitz has also been shot at by smugglers who thought he was police, and he has been detained by police, who thought he was a smuggler.
“This kind of work takes resources, money, the right personnel, and a
little faith,” Hymowitz says. “It’s like that with any basic research. This
stage of research is not putting money into anyone’s pocket, but it will have
economic benefits down the line.”
From such work also comes some unexpected spin-offs. For instance,
Hymowitz and his colleagues ended up mapping the soybean’s chromosomes in 1988—something that had been achieved with other crops, but
never with soybeans.
As Hymowitz observes, “You never know where basic research will
lead.”
F
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orbert Rocheford is looking for a few
good genes. He and his fellow U of I
“gene jockeys” are searching for and
mapping genes that control key qualities of the
corn kernel. But it’s a painstaking process, because each chromosome in corn contains thousands of genes, while only five or six of those
genes may be responsible for much of the variation of a particular corn trait.
Rocheford, an associate professor of plant genetics, is presently looking for “gene markers”
that identify those regions of the chromosome
controlling production of Vitamins E and A in
corn. Being able to control Vitamin E and A
levels in corn might have significant implications
for both animal and human nutrition.
In a 1993 study, for instance, Vitamin E supplements reduced heart disease by 41 percent
among 87,000 female nurses. What’s more,
Rocheford says, receiving Vitamin E naturally
through the food supply seems to provide greater
health benefits than taking high doses in pill
form.
Like Vitamin E, Vitamin A is an “antioxidant,” which means it too could help prevent
heart attacks. But the data on its role as an antioxidant is more conflicting than with Vitamin E.
Rocheford and his colleagues, plant genetics
professors Robert Lambert and John Dudley,
have just begun mapping the genes responsible
for Vitamins E and A in corn, and they have
done extensive mapping of other genes, such as
those controlling the oil and fatty acid content
of corn kernels.
“If we can increase the Vitamin A and E levels
in grain, the grain will be more nutritious for
human consumption or as animal feed,”
Rocheford says. “And if the grain being fed to
animals is better, the meat will also be more
nutritious.”
T
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exploring the
soybean
gene pool
PHOTO BY MATTHEW WHEELER
he gene pool that soybean
breeders draw upon today might
be better characterized as a
wading pool in terms of its depth.
Ninety-five percent of the genes in commercial soybeans today come from only
35 ancestors. Such a small gene pool
could mean stagnating yields in the future, but U of I researchers are trying to
guard against such an outcome.
Because the modern varieties that
have been derived from those 35 soybean
ancestors are so high-yielding, it makes
sense that plant breeders continue to use
those varieties as parents in creating new
varieties, says Randall Nelson, U of I
associate professor of plant genetics
and research geneticist with USDAAgricultural Research Service.
But there is a risk involved. By using
only varieties descended from these 35
ancestors, you draw from a limited gene
pool; as a result, diversity is lost from
that pool with each new set of varieties.
Eventually, this will make it more difficult to produce new varieties with higher
yields.
To safeguard against stagnating yield
rates, Nelson and his fellow researchers
are drawing upon the 15,000 lines of
soybeans in the USDA collection, which
has been housed in Urbana since 1949.
Compared to the beans that farmers
grow, the 15,000 lines are low-yielding.
But Nelson has been able to produce
high-yielding experimental lines by crossing some of the low-yielding varieties
with high-yielding commercial varieties.
What’s more, he says, the highyielding experimental lines that result are
genetically distinct from the varieties
farmers use. This research demonstrates
that it is possible to increase both genetic
diversity and yield, which may help increase the rate of yield improvement in
the future.
T
The most common method for transferring desirable DNA to swine is “microinjection.” The DNA is microinjected into a one-cell fertilized embryo. Eventually,
the injected embryo is transferred to a suitably prepared animal.
the genetic legacy of
Big Al
t all began with “Big Al”—the patriarch of a rapidly growing line
of “transgenic” pigs.
Big Al earned his fame in 1994 by
becoming the first pig to receive the
alpha-lactalbumin gene from a
Holstein dairy cow, says Matthew
Wheeler, associate professor of physiology in the U of I’s Department of
Animal Sciences. Transgenic animals,
he says, have had one or more genes
transplanted in them from another
animal.
Scientists believe that animals carrying the alpha-lactalbumin gene produce greater amounts of milk—a
factor that could boost the weight of
piglets and increase the chances of survival for animals in each litter. If milk
production would increase by as little
as 10 percent, Wheeler projects that
each piglet in an average litter could
gain 11/2 additional pounds. This boost
alone could mean 25 to 30 million additional dollars per year for the pork
industry.
Big Al, alas, is no longer alive, but
his transgenic legacy continues in the
I
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generations that he begat. Five of his
daughters and four of his sons have
carried on the alpha-lactalbumin gene.
The daughters have been bred, and as
their litters arrive, U of I researchers
monitor their milk production.
“It’s still too early to know whether
milk production is increasing,”
Wheeler says. “We’ll need at least 25
to 30 litters before we can have any
definitive answers.”
In the meantime, Wheeler is working with U of I nutritionist Sharon
Donovan to create another line of
transgenic pigs. This line of pigs would
carry a gene that produces a specific
protein to improve digestive function
in piglets and thus increase their survivability. The work carries implications for people as well, because it
may be possible to purify this protein
out of sows’ milk and add it to human
infant formula.
The same genetic technique could
be used to produce other proteins that
benefit human health.