Rick KressTrees genetically modified to resist citrus greening are grown in a greenhouse in South Florida.Slow progress in Florida is being made that some feel may be the most effective means of combating the dreaded citrus greening disease–genetically modified organisms, or GMOs.
Like thousands of Florida growers, Southern Gardens Citrus in Clewiston, which once had 2.5 million citrus trees that primarily produce juice oranges, chopped down hundreds of thousands of trees—about 25 percent of its plantings. It also sprayed a variety of pesticides in an attempt to slow the disease, all to no avail.
Then, when a worldwide search failed to find a tree that was immune to the disease or the Asian citrus psyllid that spreads it, president Rick Kress decided transgenics/GMOs may be the answer.
“We’ve got to develop a solution that solves the disease and protects the industry and is proven safe for the consumer,” Kress says. “If the researchers of the world are accurate, they’ve indicated that the ultimate solution to this disease is going to involve genetics.”
Southern Gardens embarked on a program in 2007 to develop a transgenic tree that may end up costing $20 million. The company may be able to recoup some of its investment, though, by selling transgenic trees to other growers.
Hopeful for a solution
“I believe we’re going to find a solution,” Kress says. But he admits that solution still could be five or six years away—or more.
As a first step, Kress and Southern Gardens research director Michael Irey selected five scientists to underwrite. From those five, they chose the researchers they felt would do the best job of finding a gene that would attack the bacteria or the psyllid
Two of the researchers they considered used a gene from vegetables, one used a gene from a virus and another used one from a pig. The last scientist proposed a synthetic gene.
“We fully expect that we will be able to ultimately combine research work from more than one of our researchers,” Kress says. But for now, he chose to focus on the work of Erik Mirkov of Texas A&M University, who already was working with trees into which he had spliced a spinach gene.
Mirkov says his gene-splicing technique could be applicable to citrus varieties in all growing areas, including California, Texas and Arizona, as well as Florida and, eventually, perhaps even outside the United States.
Kress quickly allayed the fears of growers by assuring them that their oranges will not take a green hue or taste like spinach.