Cracking Tomatoes’ Code
This breakthrough provides a glimpse at how the genetic revolution is helping keep favorite foods on the table. As befits this international vegetable, more than 300 scientists from 14 countries worked on the eight-year project.
Having a genetic map will provide a valuable starting point for breeders looking to make a better, hardier, more nutritious or simply tastier tomato.
“This will be facilitated now by the fact that we now know not only what genes are there, but their order,” says Giovanni Giuliano with the Tomato Genome Consortium and a researcher at the Italian national energy agency, which also does crop breeding.
Though it is the first tomato to have its DNA sequence decoded, Giuliano says there is nothing particularly special about the variety chosen for the project, known simply as Heinz 1706.
“It so happens that the day the person that made the first DNA library to be sequenced, they had Heinz 1706 seeds, and they started from that one. It is as simple as that.”
However, it was not so simple to create this tomato -- or any new crop variety.
Heinz, a U.S. food company, is famous for its tomato ketchup, but to make Heinz ketchup, not just any tomato will do. Until the late 1960s, the tomatoes the company used had a nasty habit of cracking on the vine after a heavy rain. That can ruin the tomato.
So, “Heinz had set about trying to put together a variety of tomatoes that would resist that cracking,” says company research manager, Rich Ozminkowski.
It meant years of trial and error, mating different varieties, finding offspring that looked promising, mating those offspring with other varieties, and so on.
And it was not enough for the offspring to just resist cracking. Ozminkowski says the perfect ketchup tomato needs a whole list of other traits, too.
“Traits like sugars and, for Heinz, viscosity, or the juice thickness, and the redness of the tomatoes are all very critical traits for us," he says. "Those are all controlled by a lot of different genes within a tomato naturally.”
On top of all that, it had to be disease-resistant and easy to harvest mechanically.
Commercialized around 1967, Heinz 1706 fit the bill. Ozminkowski says creating that tomato would have been much easier if they had a genetic map to go by.
“The tools available back when 1706 was developed, it was all very, very conventional breeding." Breeders had to grow thousands of tomato plants and go looking for specific traits. "There were no genetic tools," he says. "You could not look at (DNA) sequences. You could not do comparisons. And that is what makes the genomic project and the technologies that have spun off of that so interesting.”
Genome sequencing is such a powerful tool for breeders of all kinds of crops because it takes away much of the guesswork, says Heinz’s Rich Ozminkowski.
“By having the genome information, we can pick out those tomato plants that have more of those genes” for sweetness, redness, viscous juice, or whatever breeders are looking for.
It is not just about making better ketchup. Climate change will demand that many crops adjust to new conditions. Ozminkowski says researchers are already using the new genetic tools to help fight emerging plant diseases.
“This is going to give us even more [tools]," he says. That's important, he adds, "because there are new diseases that are becoming problems within California and around the world.”
From the June 4, 2012, Prepared Foods’ Daily Update