April showers bring May flowers. With a little genetic engineering, they could soon last until June. By transplanting a mutant gene into a petunia, researchers have created a flower that keeps its petals four times as long as nature intended. The gene, described in next month's issue of Nature Biotechnology, could help lengthen the life of other flowers, and perhaps prolong the shelf life of vegetables.
The normal gene codes for a receptor for ethylene, a gaseous plant hormone that ripens fruit. It also makes flowers dry up and lose their petals. In the quest for firmer tomatoes and melons, plant scientists have attempted to prevent plants from producing ethylene. But Harry Klee and his colleagues at the University of Florida realized that if a plant couldn't sense ethylene, its petals would last longer--a potential boon for commercial flower growers.
The team spliced a nonfunctional gene for the ethylene receptor, taken from a common laboratory plant called Arabidopsis, into petunias. The flowers blossomed for more than a week, instead of shriveling 2 days after fertilization. Klee says that with a little tinkering the petunias might last even longer--the only reason the petals eventually fell off the experimental flower was that they were forced off by the growing seed pod. "If you had a sterile plant, you could, in theory, get even [longer lasting flowers]," says Klee. He's optimistic that the gene will work in other plants as well, such as broccoli, which ethylene turns soft and yellow.
Plant geneticists are eager to try out the mutant receptor gene. Randy Woodson, a plant physiologist at Purdue University, says it should be valuable for carnation growers because that flower is particularly susceptible to ethylene. But he warns that the gene could have undesirable side effects in some plants: "If we indiscriminately make a plant insensitive to ethylene, we may affect its response to diseases or to pests."