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Sunflowers—today known for their tasty, crunchy seeds and a healthful
salad oil—might tomorrow gain fame as a source of premium rubber.
That's the plan of scientists who have joined forces to improve the
quality and quantity of latex from sunflower plants.
Latex is made up of rubber particles surrounded by water and other
plant compounds. It is a higher value product than solid rubber. As
rubber factories of the future, lanky sunflowers would reduce America's
dependence on imported natural rubber and on synthetic rubber made from
petroleum. The United States imported about 1.2 million tons of natural
rubber—worth about $1 billion—in 2000. Although synthetic
rubber can be substituted in some instances for natural rubber, high-performance
products such as airplane tires require natural rubber.
"More than 2,500 species of plants produce natural latex,"
says ARS plant physiologist Katrina
Cornish at Albany, California. "But few of them have the traits
we want. In particular, most are small, grow too slowly, or aren't suitable
for being cultivated in uniform stands—or monocultures. And they
don't produce enough latex, or the latex they produce is not high quality.
"In contrast, sunflowers grow large rapidly and do well in monocultures.
Although the quantity and quality of latex from sunflowers is not yet
good enough for commercial use, we expect to improve it further through
genetic engineering," Cornish adds. She is part of the ARS Crop
Improvement and Utilization Research Unit of the Western Regional Research
Center in Albany.
Cornish and colleagues are experimenting with several different types
or lines of sunflowers. "We are especially interested in lines
that produce the highest amounts of latex in stems and leaves—as
opposed to flower heads," Cornish points out. "That's because
it's impractical to separate latex in the flower head from oil and other
components. We're also focusing on lines that flourish in northern,
temperate climates, where most of the U.S. sunflower crop is grown."
At Albany, Cornish is delineating the physical characteristics of sunflower
candidates' latex and comparing them to those of latex taken from two
other natural sources—the Brazilian rubber tree and a desert shrub,
guayule. (See Agricultural Research, May
1999 and April
2002.)
Cornish will insert laboratory-built genes for latex production into
sunflower tissue. Next, she will test the tissue to determine whether
the new genes are working inside the sunflower's cells. Later, greenhouse
and field tests will identify the gene-engineered plants that produce
the highest amounts of the best quality latex. In experiments after
harvest, Cornish and co-researchers will determine how to preserve sunflower
latex while it's in storage, awaiting processing.
Cornish is a world authority on how plants produce rubber. She is doing
the sunflower project with colleagues from Colorado State University
and Oregon State University.—By Marcia
Wood, Agricultural Research Service Information Staff.
This research is part of Quality and Utilization of Agricultural
Products, an ARS National Program (#306) described on the World Wide
Web at http://www.nps.ars.usda.gov.
Katrina Cornish is in
the USDA-ARS Crop Improvement and Utilization Research Unit, Western
Regional Research Center, 800 Buchanan St., Albany, CA 94710; phone
(510) 559-5950, fax (510) 559-5663.
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