The University Record, March 11, 1998

Researcher seeks origin of scent

Clarkia breweri, an annual native to California, used by Eran Pichersky in his research on scents in plants. Photo courtesy Eran Pichersky

By Sally Pobojewski
News and Information Services

A rose by any other name may still smell like a rose, but new research by a U-M biologist suggests a rose with different genes may smell more like a banana.

Since 1990, Eran Pichersky, associate professor of biology, has been identifying specific genes and enzymes that trigger production of small organic molecules in plant cells called volatiles. When these compounds evaporate off the surface of petals and stigma, they produce a flower's scent. Each species of flower has a different scent, because each produces its own unique combination of volatile compounds.

So far, Pichersky has isolated four gene-enzyme combinations. One catalyzes the major volatile compound found in many flowers and also in oil of bergamot. The second smells like a cross between basil and cloves, the third like wintergreen, and the fourth has a strong odor of bananas.

The plant model Pichersky uses in his research is Clarkia, an annual native to California. Of approximately 25 species in the Clarkia genus, only one--Clarkia breweri--has an odor. Except for its scent, C. breweri is virtually identical genetically and morphologically to another species, C. concinna.

"It appears that C. breweri has evolved from C. concinna and so the scent of C. breweri is a recently acquired trait," Pichersky says. "Our hypothesis is that new plant species create new scent compounds simply by modifying the expression of a few key genes."

Pichersky believes all flowering plants may contain at least some of the genes responsible for floral scent. If he can figure out how plants selectively "turn on" or express specific genes during their developmental stage, scientists may one day use standard genetic engineering techniques to enhance a flower's natural odor or create a banana-scented rose. Pichersky's genes already are being used by several commercial companies. These companies are inserting Clarkia's scent genes into ornamental plants to create flowers with new scents and into vegetables, such as tomatoes, to create fruits with new aromas. Future plans call for inserting scent genes into certain crop plants, so the flowers will attract more pollinating insects and the plants will produce more seed.

Pichersky's research is funded by the National Science Foundation.