Jerusalem

A project to create a DNA database of the genes responsible for the perfume in flowers is under way at the Hebrew University of Jerusalem. Its purpose is to identify genes that can be inserted into cultivated flowers in order to improve their smell.

The project has already identified some 2,000 genes that are active in rose petals and has created a library of expressed sequence tags (ESTs) that map the genes.

According to David Weiss, a horticulturist and a member of the project team, the work has identified seven candidate genes for initiators of the biochemical processes that produce rose aromas. The next step, he says, is to study the biochemical pathways that lead from the gene, through the proteins they produce, to the substances that give the flower its pleasant smell.

“We know a lot about the chemistry of flower perfumes, many of which are produced synthetically by industry,” Weiss explains. “But we know very little about the biochemistry — the biological processes that produce the perfumes.” The work is supported by a US$220,000 annual grant from the Ministry of Science.

Weiss and his colleague Alexander Vainstein recently broke new ground. They transferred an aroma-producing gene isolated by Eran Pichersky of the University of Michigan from a wild California flower, the clarkia (Clarkia breweri), into carnations. Carnations possessing the gene, Weiss says, have a new biochemical pathway that produces the major compound responsible for the clarkia's aroma, linalool, and other fragrance-producing chemicals.

Cultivated flowers, bred for their large, colourful blooms, tend to lose much of the smell of their wild ancestors, Weiss explains. Getting the smell back into them could be a major boon for Israel's 1,600 flower-growers, who export $250 million worth of flowers each year.