Researchers in Oregon and elsewhere have discovered a new class of chemicals they call "bruchins" which, even at extraordinarily low levels of exposure, signal a plant to form a benign tumor, apparently as part of the plant's defensive mechanism against an insect pest.

The study, done by scientists from Oregon State University, the U.S. Department of Agriculture and a private company, will be published Tuesday in the Proceedings of the National Academy of Sciences.

There is no immediate commercial application that's apparent about this discovery, the researchers said, but the unusual capabilities of this group of chemicals is highly interesting. It's also the first chemical of this type ever identified that can induce tumor formation in plants, they said.

"This is an extremely active new class of chemicals that has a clear impact on plant growth regulation," said William Proebsting, a professor of horticulture at OSU. "We could observe its biological impact on the plant at levels so low we couldn't even physically detect the chemical. Whenever you find a new group of chemicals with this level of activity you get a little excited. And this is also the type of basic discovery that often sets the stage for later applications."

In this research, the scientists studied the interaction of pea plants with pea weevils, a tiny insect that's smaller than a ladybug but is one of the worst insect pests of peas. In order to reproduce, the pea weevil needs to lay its eggs on a pea pod. But the pea plant has apparently developed an innovative and effective response to this insect attack.

When the egg is laid, the pea plant detects in the pea weevil a type of chemical, which the Oregon researchers identified and are calling bruchins, in reference to the scientific classification, bruchid, to which pea weevils belong.

This chemical triggers the pea pod to begin a process of cellular division that actually forms a small tumor, lifting the pea weevil egg up
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Contact: William Proebsting
proebstw@bcc.orst.edu
541-737-5454
Oregon State University
14-May-2000