Researchers Seek Genetic Cause for Tomato Growth
Posted on: Monday, 12 May 2008, 13:25 CDT
Researchers are trying to understand which genetic changes have caused tomatoes to become almost 1,000 times larger than their wild ancestors.Steven Tanksley, plant geneticist at Cornell University in Ithaca, New York, is trying to determine what allowed humans to change wild tomatoes into modern varieties like the beefsteak tomato, which can weigh a pound or more.
"The cherry tomato would be considered very large compared to what is found in the wild," Tanksley said.
"Humans began domesticating plants in the last roughly 10,000 years. They had no knowledge of genetics and no knowledge of breeding, but somehow they rendered these changes genetically on plants.”
“The question we're asking is how and what did they do?"
These genetic changes have resulted in a larger number of compartments inside of tomatoes, Tanksley said.
"If you take a beefsteak tomato from the supermarket and cut it open inside you'll see these compartments in there that have wells between them . They may have anywhere from 10 to 20 of these compartments," said Tanksley, whose research appears in the journal Nature Genetics.
A true wild tomato may have only two to four of these.
"Somehow, something made the plant start making these compartments, and by making more compartments, you can get larger fruit."
The process began by making a map of the tomato’s 30,000 genes.
After narrowing down the suspects to a total of about 10, Tanksley’s team said they found one called "fas" with a large mutation.
"It was a smoking gun," Tanksley said.
None of the wild tomatoes they studied had this mutation.
Tanksley said this mutation weakens a signal that tells the plant to stop making compartments.
Tanksley said he is still surprised at the complex process that tomatoes underwent, even during prehistoric time.
"What's marvelous is that humans did this with no knowledge of genetics ... yet the impact was so enormous," he said.
"This knowledge may help us in the future to have a renaissance of plant domestication, because we are basically living off what humans did in pre-history."
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Steven D. Tanksley, Cornell
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Source: redOrbit Staff and Wire Reports
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