MSU discoveries upend traditional thinking about how plants make certain...( EAST LANSING Mich. Michigan State U...)

EAST LANSING, Mich. Michigan State University plant scientists have identified two new genes and two new enzymes in tomato plants; those findings led them to discover that the plants were making monoterpenes, compounds that help give tomato leaves their distinctive smell, in a way that flies in the face of accepted thought.

Such research could help researchers find new ways to protect plants from pests.

Based on years of research, scientists thought that plants always used a specific compound, geranyl diphosphate, to make monoterpenes. But MSU biochemistry and molecular biology scientists Anthony Schilmiller and Rob Last were part of a research team that has found that tomato plants use a different compound, neryl diphosphate, as the substrate for making monoterpenes. The difference is subtle, but the discovery will change the way terpene (compounds that are responsible for the taste and smell of many plants) research is done. The research is published in the May 25 issue of the Proceedings of the National Academy of Sciences.

"Essentially, this work subverts the dominant paradigm about an important and widespread pathway in plants," Last explained. "For years it was known that monoterpenes are made in a specific way. But there were cases where that pathway likely wasn't involved, given the kinds of compounds found in specific plants. We showed that in tomato trichomes (small hair cells located mainly on the plant's leaves and stems), the established pathway is wrong. In the tomato trichome, two enzymes work together to make the monoterpenes in a previously unsuspected way."

The two newly identified genes, neryl diphosphate synthase 1 (NDPS1) and phellandrene synthase 1 (PHS1), cause the tomato plant to make the new enzymes that produce the monoterpenes.

As the team was sequencing the DNA of tomato trichomes, Schilmiller and Eran Pichersky, of the University of Michigan, noticed that there were many sequences
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