But Nessler says we shouldn't expect to see the rat-altered lettuce in grocery stores. "We realize that a plant altered by a rat gene wouldn't appeal to consumers," he says.
He and his colleagues are using what they've learned from the rat-gene work to try to discover other ways to stimulate the Vitamin C gene in lettuce and other plants.
Nessler chose to use rats in his research because the gene was readily available and rodents are natural producers of Vitamin C.
"The reason sailors on their way to the new world got scurvy while rats thrived was because humans have lost the ability we once had to make our own Vitamin C, while rats have retained it," he explains. Humans still have the gene, but a genetic defect has rendered it inoperative.
Nessler says his work is a specific way to do what nature has been doing throughout the earth's history - the hybridization of plants. "Nature does it by chance, and farmers have been doing cross-pollination by hand for years," he says. "But now we have the ability, through biotechnology, to be very specific in what new traits we introduce into plants."
According to Nessler, the method plants use to produce vitamin C is virtually unknown to scientists. They do know, however, that the vitamin serves as a preservative, and theorized that if they could increase the level of Vitamin C in lettuce, the product would have longer shelf life. It also might help keep salad-bar lettuce fresh - which would be welcomed by the restaurant industry. Vitamin C is a natural product, in contrast to biosulfites, which the FDA banned from use on raw foods because one out of 100 people has an allergic reaction to them.
Nessler says that the timing of his experiment was fortunate. Shortly after he and his colleagues had successfully introduced the gene into lettuce, another scientist's paper stated that plant and animal biochemical pathways differed so much that animal genes could not work in plants. So, theoretically, he says, the experiment shouldn't have worked - and if he had read and believed the conclusions of that article, he might never have attempted it.
"Because they are immobile, plants tend to have better biochemistry than animals," Nessler says. He theorizes that plants may have both plant and animal pathways, or that there may be a stronger connection between the pathways than previous research has shown.
Although Nessler does not think that lettuce enriched in Vitamin C through rat genes will ever be commercially available, he does hope that his research will result in more acceptable ways to turn on latent vitamin production in lettuce and other crops. His hope, he says, is that the discoveries from his research will one day improve the nutrition of people in developing countries. "It's important that people with limited food resources get more vitamins into their diet, if they are to survive and be healthy," he says.
He notes that research has provided evidence that Vitamin C and other antioxidants also help prevent symptoms of aging related to dementia.
"This kind of technology is extremely good for both mankind and the planet," Nessler says. "With the precision of the scalpel, we can breed very specific traits into plants. Most efforts in the past have been directed at making it easier for the farmer to produce good crops. We're using this same kind of biotechnology in an attempt to improve the plant for the consumer."
And someday, Nessler hopes, a big salad may be just as rich a source of Vitamin C as a tall glass of orange juice.
Nessler has been awarded funding by the National Science Foundation and U.S. Department of Agriculture to continue his research.
Contact: Craig Nessler
Head, Department of Plant Physiology, Pathology, and Weed Science
Blacksburg, VA 24061
PR CONTACT: Netta Benton