Inhibiting the expression of a specific gene can often result in new traits. In tomato, the softening that occurs during ripening is partly due to an enzyme called polygalacturonase. CalGene has transformed tomatoes with an "antisense" polygalacturonase gene, which interferes with the expression of the normal polygalacturonase gene. As a result, polygalacturonase production in fruit is slowed, which in turn slows the ripening process. Firm fruit can be shipped with minimal damage, and ripen on the shelf.
Marketed under the trade name Flavr Savr®, this is the first transgenic food to be sold commercially.