Through gene sequencing, scientists have created a genetic roadmap of the grape.
Molecular biologists, such as Zhijian Li, then must identify promoters—snippets of DNA that control the expression of a genetic trait.
Already, he has a three-page list of promoters.
"We found we didn’t know how many promoters there were,” Li says.
Gray and his team also are using marker-assisted breeding. They attach a small piece of benign genetic material to the desired trait, such as a gene that regulates anthocyanin production in plants.
Because the anthocyanin gene causes production of a natural reddish pigment, breeders can quickly tell whether the desired trait that’s attached to the marker gene was transferred.
Growing vines in the lab
Once they have what they think is the correct genetic mix, technicians will then use tissue culture to propagate plants.
Tissue culture involves exposing a small clump of plant cells to various nutrient broths that contain specific plant growth hormones.
One hormone, for example, may promote root development, whereas another will promote leaf formation.
All of this is done under nearly sterile conditions, resulting in plants that are disease-free.
After the tissue culture begins to resemble a grapevine, technicians transplant it to potting medium and place it in a greenhouse.
The entire process has taken Gray and his team several years to perfect, and the University of Florida holds several patents on it.
Eventually, the vines are moved to the field for evaluation of agronomic characteristics and fruit quality. Once his lab gets revved up, Gray says it could take as little as one year from tissue culture to vines in the field.
In addition to plots at the IFAS center in Apopka, the new vines also will be put into plots in the Virgin Islands and into an existing variety evaluation trial in Poplarville overseen by Stephen Stringer, an ARS research geneticist.
“We’ll be able to tell even with a small number of plants how they’ll perform against the varieties that are already growing there,” Gray says. “Steve has a lot of experience and feel for the crop, and there’s a lot of experience that comes into evaluating these things.”
Gray and his team use Thompson seedless as what he calls their laboratory “white mouse”—or test animal—because of its acceptance to precision breeding and tissue culture.