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In the mountains of northern Thailand, rice farming is an age-old occupation
largely untouched by the modern world, June 2005 by Sara Shipley.
Farmers hand-cultivate rice from seeds varieties their ancestors have
saved for thousands of years.
No high-yield hybrid plants or genetically modified seeds exist there -
leaving intact a treasure-trove of rice varieties sprinkled among small
For the past three years, Washington University evolutionary plant biologist
Barbara Schaal has used cutting-edge science to explore the genetic
diversity of one of the world's oldest and most important food crops. Her
goal is to help protect unique varieties of native rice while improving the
yield of a grain that feeds more than half of the world's 6.4 billion
"When a plant is domesticated, it loses 80 percent of the genetic diversity
of the wild plant," Schaal said. "That's why it's so important to preserve
the wild ancestor."
In an effort to feed the world's growing population, some countries are
considering planting rice that has been genetically modified to resist pests
or contain higher nutrient levels. China is expected this year to become the
first nation to approve genetically modified rice despite critics' concerns
about possible environmental and health impacts.
Already, many Asian farmers have left traditional rice varieties behind in
favor of modern hybrids that were bred to grow stronger and better. While
this "Green Revolution" has doubled or tripled the crop yield, rice
biodiversity - the abundance of unique genetic varieties - has waned.
Thailand is an exception. Only about one-fifth of its rice crop comes from
high-yielding hybrids. In remote mountainous regions of Thailand, India,
Myanmar, Laos and Vietnam, many villagers still cultivate their own special
strains of local rice.
Those villages are like living museums for plant geneticists. Schaal found
particularly fertile ground for her research among the people of the
indigenous Karen tribe in the northern mountains of Thailand.
Expert farmers in each village carefully select the seeds best for local
growing conditions from rice plants with different traits. Over centuries,
each village developed an average of 15 distinct varieties, Schaal and her
collaborators found. The researchers used DNA sequencing to determine
The researchers found some important differences that could be used to help
improve the world's rice supply, including better disease resistance, high
iron content and tolerance to metals.
They also found variety in the shape, color, taste and texture of rice
grains. Some farmers bred a particularly sticky, glutinous rice. One farmer
saved the seeds of a pretty reddish-brown rice just because he liked it.
Another kind of small, high-quality round-grain rice is prized as food for
valuable fighting cocks.
"In one village, I saw a chicken being exercised on a treadmill, cleaned and
massaged," Schaal said with a laugh.
Benjavan Rerkasem, a co-investigator at Chiang Mai University in Thailand,
said she is fascinated by the local farmers' ingenuity.
"They manage to make use of Thailand's rich rice genetic resource,
especially in areas where 'improved' modern varieties from the national
breeding program have for some reason not been able to reach," she said.
The growth of large-scale agriculture makes it increasingly important to
preserve genetic variety, said Peter Raven, an internationally recognized
scientist who directs the Missouri Botanical Garden.
"With world trade in crops and movement of crops around the world, we need
every bit of that genetic diversity to make the crop resilient to adapt to
different habitats and to respond to global warming," said Raven, who called
Schaal "one of my favorite people."
For Rerkasem, the rice research has significant implications for the future
of agriculture in her country.
"It is possible to have economically viable rice production systems that are
based on genetically diverse local varieties," she said. "So here we have
win-win situations where farmers can get good return from rice farming while
conserving genetic diversity in the field."
While some would prefer not to introduce genetically modified rice to the
mix, Schaal is not opposed to its use - with controls. Her research has led
her to believe that biotech rice could naturally interbreed with wild rice,
posing a threat to native plants and domestic rice.
That discovery came when Schaal explored the genetic origin of a strange,
weedy rice found growing in a domestic rice paddy in Thailand. Her DNA
analysis proved that the domestic plants had bred with wild rice to produce
a monster weed. The new plant eventually took over the rice field and spread
to neighboring fields.
Schaal said her finding "means that GM rice could cross with wild rice.
Which means if GM rice is introduced, it would have to be managed. It
wouldn't have to be banned."
In St. Louis, students are experimenting with crossing biotech rice and wild
rice in the lab. Schaal's husband, St. Louis University biology professor
Joe Leverich, is helping with the work.
The rice project, which is funded by the U.S. Agency for International
Development, has a multidisciplinary approach. Anthropology students are
tracking how the movement of human genes compares with the flow of rice
"A family will have a variety of ancestral rice, and they pass it on to
kin," Schaal said. "We think the genetic information and sociological data
will be linked because of seed sharing."
Rice is only the latest research subject for the German-born Schaal, who has
two children. Her earlier work on cassava, a root crop that is the source of
tapioca, Mead's milkweed and other plants earned her membership in the
National Academy of Sciences, an esteemed body of researchers that provides
advice to the federal government and the public on issues such as health
care, the environment and public transportation.
This year, she became the first woman to be elected vice president of the
organization, an honor that didn't come as a surprise to her colleagues and
"She's so enthusiastic, it's amazing," said Sarah Fox, a Washington
University Spanish major who took Schaal's "Plants and Civilization" class
just for fun. "It's one of the best classes I've taken so far."
Schaal is known for bringing students edible treats made from exotic plants:
cassava muffins, cooked quinoa, coconut milk, arrow root cookies, chips made
from sweet potatoes and taro roots.
She urges students to think of plant evolution as a living, breathing thing
that deeply affects the world today. "This is not something that happened in
the dark human past."
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