Toxin-free castor would be major help to industry

MISSISSIPPI
STATE – The castor plant thrives in Mississippi and produces great
quantities of valuable oil in its seeds, but it has a reputation that a
team of researchers at Mississippi State University are trying to
address.

Castor oil is the highly desirable, plentiful product of castor beans.
The oil is used to produce everything from cosmetics and paints to jet
aircraft lubricants and certain plastics. Generations ago, it was given
by the spoonful as a laxative and used as a home remedy to treat a
range of maladies.

Today, castor oil still has many
desirable properties. The thick oil makes up 60 percent of the seed’s
weight. For comparison, high oil corn or canola only produce about 25
percent oil by weight. Ninety percent of the oil is ricinoleic acid, a
fatty acid found in large quantities only in castor oil. The acid has
many industrial applications.

Brian Baldwin, a Mississippi
Agricultural and Forestry Experiment station researcher in MSU’s
Department of Plant and Soil Sciences, said castor can be used as a
biodiesel but is more important as an organic raw material for
industrial chemical processes. Because of Mississippi’s climate, the
crop could be grown very successfully in the state.

“Castor
seed yields in Mississippi can exceed one ton per acre,” Baldwin said.
“That seed can produce 1,000 pounds of oil per acre, which is a much
higher rate than other high oil-content seeds produce.”

Daniel Barnes, a doctoral student in MSU’s Department of Biochemistry
and Molecular Biology, is trying to make it possible to grow the plant
safely for commercial oil production in Mississippi. Castor seed meal,
not the oil, contains ricin, a toxic protein that can become fatal if
untreated in the body.

“Castor is the only place we can get commercial quantities of
ricinoleic acid, but because of the presence of ricin, we are not
producing castor in the United States,” Barnes said. “We want to get
rid of the ability of the plant to make the toxin altogether.”

There is no law or restriction against the domestic production of
castor, but Barnes said castor has not been grown commercially in the
United States since the 1970s. It is often planted as an ornamental in
Southern gardens.

“We import every bit of castor oil and caster seed, mainly from India and China,” Barnes said.

Once imported, the oil often must be refined and filtered yet again to meet Western industry’s quality standards.

“This is an expensive two-part process. We are importing a product that
could be grown here, and then we have to re-refine it,” Barnes said.

To make castor a commercially viable U.S. crop, he is trying to
discover a way to genetically modify the plant so that either the gene
that produces the toxin is no longer expressed or the toxin is no
longer produced.

One of the challenges is that castor
resists being transformed. The genetic modification process involves a
fragment of DNA foreign to the plant being inserted into the genetic
code, where it is accepted and becomes active.

“Everything
from cotton to corn and soybeans has been genetically modified, but
castor is much more difficult. The castor cells can be transformed, but
then you can’t get whole plants to grow from the cells,” Barnes said.

Compounding the problem is that castor is the only species in its
genus, so there is no other plant like it. Poinsettia, spurge and
rubber trees are among castor’s closest biological relatives, and these
and other somewhat closely related plants are being examined to see if
they contain genetic code useful to the castor research.

“We’re starting from scratch,” Barnes said. “That’s what makes it a wonderful question for research.”

Barnes has been working on ricin in castor for four years. He earned
his master’s degree from MSU examining ways to reduce workers’ exposure
to ricin in the production process. Now he is trying to actually remove
this toxic protein.

The project is being conducted by faculty in MSU’s departments of
biochemistry, plant and soil sciences and biological sciences. Others
involved in the interdisciplinary team are Ken Willeford in
biochemistry, and Donna Gordon and Nancy Reichert, both in biological
sciences. Funding is through MSU’s Sustainable Energy Research Center
and the Office of Technology Commercialization.

Further Information: http://msucares.com/news/print/agnews/an10/100715.html