Science / Medicine : Genetic Method Controls Ripening of Tomatoes

From Times Staff and Wire Reports

California scientists have used genetic engineering techniques to produce tomatoes that do not ripen on the vine, during transit after they are picked and during storage. The technique could lead to less spoilage and to fresher, better tasting tomatoes.

Tomatoes, as well as many other fruits, vegetables and flowers, trigger ripening by releasing a colorless, odorless gas called ethylene. Many growers and shippers now pick tomatoes while they are green to reduce damage during handling. They must be kept cold during shipping and storage to minimize release of ethylene. Ripening is then achieved by exposing them to ethylene, but because the tomatoes were picked before they matured, they are often hard and flavorless.

Molecular biologist Athanasios Theologis and his colleagues at the U.S. Department of Agriculture in Albany and UC Berkeley reported last week in Science that they had used so-called anti-sense RNA technology to block the production of ethylene in tomatoes. The tomatoes can then be allowed to fully mature on the vine, be transported and stored without refrigeration and then stimulated to change color and soften by adding ethylene.