If a trait can be transferred to Thompson seedless, the team tries it next on muscadines, which are more temperamental, and other varieties.
So far, Gray says he’s successfully transferred the gene for powdery mildew resistance from chardonnay into Thompson seedless.
The resulting plant isn’t immune from powdery mildew. Instead, precision breeding gives the vines seven to 10 additional days before mildew infection incurs. This could potentially reduce the number of fungicide treatments growers applied during a season.
\n addition, sour-bunch rot was reduced by 42 percent compared with the control, and black rot infection was cut in half.
Benefits beyond muscadines
Eventually, Gray says he’d like to use precision breeding to impart seedlessness and disease-resistance to the Delicious muscadine variety, a University of Florida release.\
Not only does Delicious have excellent yield and eating quality, but it’s also self-fertile and doesn’t need a pollenizer variety, he says.
Many other muscadine varieties are exclusively female. For those to bear fruit, they must be in close proximity to a self-fertile variety to pollinate.
If all goes well, Gray says it will take about seven years from the project’s start until a seedless disease-resistant muscadine appears on grocery store shelves.
The benefits of the gene-transfer technology go far beyond just muscadines and could benefit the entire grape industry, Gray says.
The disease resistant portion itself could really, really help the bunch grape growers here in Florida, since they have disease issues,” Burgess says. “If he could put the disease-resistance into those [varieties] like he did the Thompson seedless, we could have a lot larger varieties of grapes that we could grow and grow well.”
Gray also points to a vineyard of several winegrape varieties at the Apopka research center that contain varying degrees of Pierce’s disease resistance.
An earlier gene-transfer technology was applied to the vines, but Gray says there’s no reason why precision breeding couldn’t be used to develop Pierce’s disease-resistant plants.
Muscadines have natural tolerance to Pierce’s disease, but many other grapes, such as winegrapes—known scientifically as Vitis vinifera—are susceptible.