Helping Mother Nature
For the past 30 years, Scott and other tomato breeders have been unsuccessful in developing a bacterial spot-resistance tomato using conventional breeding techniques.
As a breeder, Scott says he looked for better resistance in related tomato species.
Finding none, he then looked to a gene, known as Bs2, found in many bell and hot peppers that is responsible for bacterial spot resistance.
Although peppers and tomatoes are both members of the Solanaceae family, they won’t crossbreed.
So Scott, in cooperation with UF plant pathologists Bob Stall and Jeff Jones, started testing transgenics that had the Bs2 gene from peppers transferred into tomatoes.
Researchers in Brian Staskawicz’s laboratory, University of California, Berkeley, made the original transformation, inserting the Bs2 gene into VF 36, an old California variety that is highly susceptible to bacterial spot.
Scott’s trials in Balm showed the transformed variety not only withstood bacterial spot with few symptoms, but it yielded significantly more than its conventional counterpart.
The conventional California variety, on the other hand, had about 80 percent infection.
The Bs2 gene was then inserted into Fla. 8000, a parent of the Florida-adapted hybrid Fla. 8314. And the Fla. 8000 Bs2 parent was used to develop FL 8314 with the Bs2 gene.
Two seasons of field trials have yielded results even surprising Scott.
“The yields are essentially double, which is quite remarkable,” he says. “Same for the extra large yield.
“I don’t know a single thing that is wrong with [the gene} where it does something bad in tomatoes. I haven’t seen anything that affects yield, firmness or marketability.”
They were compared to conventional counterparts, which had high rates of bacterial spot infection and much lower yields.
Scott says he’s noticed that the transgenic tomatoes also had less early blight infection in recent replicated trials.
The reason for this unexpected result is not known, but he says it might be that the lack of bacterial spot damage makes it more difficult for the early blight fungus to attack the plants.
Growing tomatoes without copper applications would free producers from a burdensome disease and allow them to improve integrated pest management efforts toward other diseases, Vallad says.
The next step