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Basil Nikolau, Biochemistry, (515) 294-9423
Eve Syrkin Wurtele, Botany, (515) 294-8989
David Oliver, Botany, (515) 294-0134
Teddi Barron, News Service, (515) 294-4778


AMES, Iowa -- For 30 years, plant scientists have searched for the source of the compound that plants use to create oil. The mystery may have been solved by three groups of researchers at Iowa State University.

Their discovery could make it possible for plant breeders and genetic engineers to adjust the oil-producing capacity of soybeans, corn and other plants.

The three groups are led by Basil Nikolau, biochemistry professor and interim director of the Center for Designer Crops; David Oliver, botany professor and department chair; and Eve Syrkin Wurtele, botany professor. The research has been published in the journal, Plant Physiology.

Soybeans and other plants with oil-producing seeds are a significant source for the oil used in edible products (salad dressings, cooking oils, etc.) and industrial products (lubricants, paints, etc.).

Commercial oils produced by plants are made from the biosynthesis of fatty acids. The precursor for this biosynthesis is acetyl-coenzyme A (acetyl-CoA). Acetyl-CoA also is the "starting material" for the biosynthesis of several other compounds.

"The fact that acetyl-CoA is a starting material for other things complicated the discovery of its source," Nikolau said

Over the past 30 years, a dozen or so laboratories worked on the complex problem, suggesting various solutions without finding the definitive answer.

About four years ago, Nikolau, Wurtele and Oliver were able to take advantage of new sequencing data available from the Arabidopsis plant genome project. Their research groups worked independently, studying different parts of the same puzzle, in search of genes that could make acetyl-CoA.

What they found was unexpected. By the late 1980s, most scientists working on this problem hypothesized that acetyl-CoA was made by the enzyme acetyl-CoA synthetase (ACS).

"We found that another enzyme–pyruvate dehydrogenase (PDH)–which was known to be involved, was actually responsible," Nikolau said.

"We looked at how the ACS and PDH coding genes are expressed during the development of the seeds when oil was being produced in the seeds. It turned out that the PDH gene is coordinately expressed as other fatty acid biosynthetic genes consistent with its role in making oil, but the expression of the ACS gene was not coordinated with the other fatty acid biosynthetic genes or oil accumulation," Wurtele said.

Scientists in Britain and at Michigan State University, who are studying the same problem from a very different approach, are coming to the same conclusion, Oliver said.

Iowa State has a patent pending for the genes and for methods of altering acetyl-CoA generation. The Iowa State researchers are working on the absolute proof that PDH is the source. "By eliminating the ACS and PDH genes one at a time, we can see which one effects oil formation," Nikolau said. "When we eliminated ACS, there was no effect on oil."

The Center for Designer Crops is one of nine research centers in the Plant Sciences Institute at Iowa State University.


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