Transgenic tomato withstands bacterial spot, yields more fruit

10/08/2012 01:11:00 PM
Vicky Boyd

transgenic tomatoesCourtesy Two Blades FoundationThe tomatoes to the left are the Fla. 8314 variety into which the Bs2 bacterial spot-resistance gene has been inserted. The tomatoes to the right are VF 36, which is extremely susceptible to bacterial spot. When a gene from bell and hot peppers is inserted into tomatoes, it not only imparts resistance to bacterial spot—a devastating tomato disease—it also bumps up yields.

Jay Scott, a University of Florida tomato breeder at the Gulf Coast Research and Education Center in Wimauma, admits a small segment of the population opposes transgenic crops.

But he says the benefits of a bacterial spot-resistant tomato to the environment and growers would be a strong selling point.

“We still have to overcome different views on transgenic crops,” he told attendees of the recent Florida Tomato Institute in Naples. “My personal feeling is most people just don’t care.

“We need to emphasize to the public that this is a green technology. We’re using less pesticide and putting less contaminant into the environment.”

Transgenic tomatoes are nothing new. The now-defunct Davis, Calif.-based Calgene introduced the first transgenic crop—the Flavr Savr tomato under the MacGregor’s label—in the 1990s.

Because of shortcomings with the trait, Flavr Savr tomatoes never took off, Scott says.

But consumers back then actually wanted the tomato because it was genetically engineered, he says.

“If it was successful, we might have a different attitude today,” Scott says.

The need for disease control

Growers apply an average of $500 worth of copper and mancozeb annually to try to control bacterial spot—one of the most devastating tomato diseases along the East Coast—without much success.

Statewide, tomato growers spend about $28 million on copper and $14 million on mancozeb annually to fight the problem, he says.

Gary Vallad, assistant plant pathology professor at the Gulf Coast center, has conducted numerous field trials to try to find effective bacterial spot controls. Outside of streptomycin, an antibiotic not registered for field-grown tomatoes, nothing has stood out.

Even then, antibiotics provide at best 85 percent control and no significant yield improvement, he says.

Actigard, an SAR—or systemic acquired resistance—product produces at best a 35 percent reduction in bacterial spot symptoms. But it does little to improve yields, Vallad says.

Copper, the industry mainstay, is relatively ineffective since most strains of Xanthomonas—the organism responsible for bacterial spot—have grown resistant to it, he says.

Copper also has come under fire because it can build up in the soil to toxic levels.

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Pedro Pompeyo Osores Morante    
Peru  |  September, 14, 2012 at 10:37 AM

The chemicals companies are wrong the transgenic crops will makes resistance by acelered mutations in diseases like Bt transgenic,Cry transgenic and others cases With propaganda campaign only whant win time for a bisness of 50 billion dolars its falling down around the world

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