Root Beer-Smelling Roses? Pick Your Scent

Feb. 14, 2010— -- Root beer-scented roses could soon be available at your local florist, according to scientists from Florida who are developing newly fragrant flowers.

The research could lead to custom-designed flower fragrances and even to better-smelling, and better-tasting, fruits and vegetables.

"We are very excited about the idea of putting these flowers in front of consumers and figuring out which fragrance excites people the most," said David Clark, a scientist at the University of Florida in Gainesville developing the new flowers. "Then we can use that information to assist breeders in developing flowers that people want to smell more, or even breed fruits that smell and taste better."

The key to a flower's aroma is in its genes. Over the last 50 years plant breeders consciously selected for bigger and prettier flowers and fruits. Along the way the genes that make flowers smell nicer have been lost. Clark and his colleagues have discovered those genes, albeit by accident.

The scientists were studying petunias, trying to increase the lifespan of petals. The researchers had no particular interest in petunias as objects of beauty or symbols of desire; petunias are a model system for tomatoes, as well as potatoes, tobacco and other edible crops. One way to get more tomatoes is by pollinating more flowers.

This is not as easy as it sounds. A pollinated flower releases ethylene gas. Ethylene makes the petals fall off unpollinated flowers. If the scientists could find a gene that stopped ethylene production or ethylene detection, then the likelihood of an unpollinated flower becoming pollinated, and becoming a tomato, increases.

To find genes linked with ethylene, the Florida scientists sequenced the petunia's genome. They found the ethylene genes, but they also found an unexpected blank spot on the petunia's genetic map; 12 to 13 new genes that encoded for molecules of unknown use.

Through a variety of genetic techniques, the scientists knocked out, amplified, and otherwise tweaked each of these genes until they found their function. Those 12 to 13 genes tell the plant to produce rose oil, clove oil, wintergreen, the smell of root beer, and other chemicals that, when whiffed together, give a petunia its distinctive aroma.

These genes identified, scientists can now create flowers with never-before- smelled scents, including roses that smell like root beer or petunias that smell like wintergreen.