Gene Could Help Veggies, Fruits, Flowers Last Longer

A researcher at UF's Institute of Food and Agricultural Sciences has identified a mutant gene that regulates the gas ethylene in plants and could one day allow growers to slow the ripening of vegetables or the wilting of flowers.

Building on the work of University of Wisconsin researchers who detailed how plants recognize and then inhibit ethylene, UF Eminent Scholar and Professor Harry J. Klee identified a specific gene that greatly slowed ripening in the Never-ripe tomato.

``Ethylene is the compound that controls fruit ripening in many species that are critical to Florida horticulture,'' Klee said.

Ethylene is already applied externally to many crops to speed ripening just before they are shipped to market. Fruit are picked green, when they are less likely to bruise or rot, then later encouraged to ripen by ethylene treatment.

But the problem could be overcome more efficiently, and with better final quality, by genetically engineering plants with delayed ripening cycles.

The tomato, for example, is generally harvested when about 85 percent of the crop is still green and hard. Even with ethylene application, many of these tomatoes, particularly winter tomatoes, don't reach full flavor and ripeness at market.

But if the ripening could be manipulated, said IFAS postharvest physiologist Jeff Brecht, the tomato could be harvested at a more mature stage and reach the market in a tastier condition.

Tomatoes are the top vegetable crop in Florida, accounting for about half of the total value of vegetable crops and generating about $700 million in economic impact annually, Brecht said.

IFAS environmental horticulturist David Clark sees a similar economic impact of ethylene research on the state's $600-million-a-year floriculture industry.

While ethylene regulates ripening in tomatoes, it causes flowers to wilt.

But by inserting the mutant ethylene gene into petunias, Clark has been able to produce plants whose flowers last two to three times longer than a regular petunia. The genetically altered petunias also are able to hand down their resistance to ethylene to their offspring, proving that the trait can be inherited.

``We're looking to take this technology into other flower crops,'' Clark said. ``We want to improve the vase life of cut flowers, and we want to improve performance in the garden and the landscape.''

Shipping and handling is always a problem with flowers, Clark said, because flowers cut for shipping often emit ethylene gas which, in turn, causes them to wilt.

``A plant we normally might be able to ship for only two days, we might now be able to ship for four days,'' Clark said, adding that he expects to see ethylene-resistant plants available commercially by the turn of the century.

photo by: Thomas Wright

University of Florida eminent scholar Harry Klee has isolated a mutant gene responsible for thwarting the ripening of tomatoes --- opening the door to widespread manipulation of shelf life for economically important fruits, vegetables and flowers.