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UF Researcher Uses Gene To Produce Longer-Lasting Flowers

GAINESVILLE—The petunias in University of Florida researcher David Clark’s greenhouse are the Energizer bunnies of flowers — they keeping blooming and blooming and blooming.

And if Clark’s experiments work on other flowers, Florida’s $600-million-a-year floriculture industry may see its bank accounts blossom as well.

Clark, an environmental horticulturist in UF’s Institute of Food and Agricultural Sciences, is conducting experiments on petunia plants containing a mutant ethylene receptor gene. The genetic engineering makes the plants insensitive to ethylene, a gas that causes flowers to wilt.

The gene is taken from the weed, Arabidopsis, which Clark says is so useful in research that it is the plant world’s equivalent of the white laboratory mouse.

So far, Clark’s experiments have shown that the plants produce flowers that last two to three times longer than a regular petunia. The transgenic 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. We want to improve the vase life of cut flowers and we want to improve performance in the garden and the landscape,” Clark said. “If we make flowers last longer, the flower industry can make a whole lot more money, and we can produce something that you’ll enjoy a lot longer.”

Although petunias are the first important flowering crop making use of the mutant ethylene receptor gene, the gene is not new to UF laboratories. In December, UF Eminent Scholar and Professor Harry J. Klee’s use of the gene in tomatoes was detailed in “Science.” His genetically engineered tomato plants with a delayed ripening cycle could be a major boost to the state’s $700-million-a-year tomato industry.

Clark concedes a bias toward floriculture but said the research with the mutant ethylene receptor gene may have a greater potential benefit with flowers than with tomatoes.

“I see this as having an extremely broad scope in floriculture,” Clark said. “We have a large number of floriculture crops that are sensitive to ethylene. With tomatoes, you’re talking about one very large crop, but with flowers, we’re talking about being able to span the industry.”

Flowers with the ability to bloom longer will open new markets to the floriculture industry, Clark said.

Shipping and handling is always a problem with flowers, Clark said, because stems are cut, boxed and shipped from point A to point B. The flowers often emit ethylene gas in response to being cut and, in turn, wilt in response to exposure to ethylene.

“A wounded plant gives off ethylene gas, and a cut flower is wounded,” Clark said. “By using plants insensitive to ethylene we can deal with extremes a little bit longer, instead of having to control shipping conditions.

“For example, 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. “And that means, if we could normally ship from Florida to Texas, now we can expand our markets to Washington state and California. Somewhere very far away.”

So when can florists and nurseries and landscapers get their hands on these long-blooming plants?

“They want it yesterday,” Clark chuckles. “But realistically, I think you’ll see these plants commercially available by the year 2000, probably sooner with petunias.”

Clark says the floral industry is well aware of the gene and following its use in research closely.

“They’re chomping at the bit right now,” Clark said. “The one most important thing in floriculture is new varieties, new cultivars, they always want something better.

“With the varieties we have on the market today, we can produce a beautiful flower. You can look, and you can see beautiful flowers everywhere,” Clark said. “But to make them last a long time, too, that’s the icing on the cake.”

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