Part two in a series. Can science save citrus?

Part two in a series. Can science save citrus?

Transgenic trees may be the best solution to citrus greening disease.

In part one of this series we outlined the problem plaguing Florida’s $9 billion juice industry. Citrus greening attacks orange trees and leaves fruit bitter, half-green and oddly shaped. The ultimate net effect is that the tree will die because it’s not getting nutrients, and a newly planted tree is more susceptible because it’s smaller. In severely affected cases, the fruit will fall off the tree.

Industry leaders are examining several options to solve the citrus greening problem. They looked worldwide for a naturally immune tree, but could not find one.

Related: USDA awards $20 million in grants for citrus greening research

Transgenic trees may be the best solution to citrus greening disease.

With the disease worsening, they began to realize they could not wait for answers via conventional breeding. Developing a better citrus tree, even under normal situations, means a year in the nursery, and then five to seven years before sufficient fruit provides a return on that tree.

An industry consensus emerged, focusing on genetic engineering as a likely answer — despite the public relations nightmare that would likely follow. When the National Academy of Sciences began looking at the greening problem in 2009, it labeled it as one of the most serious diseases the academy had dealt with, and indicated that biotech would likely be part of the long-term solution.

That meant a whole different approach for the industry — not only for research, but also for regulations, agricultural practices and consumers.

“There’s a strong awareness of our research, but we’ve done that by design,” says Southern Gardens Citrus president Ricke Kress. “We want everyone to understand: This disease is a challenge, and biotech could be an answer.”

“If we could find a solution that wasn’t biotech, we would be all for it, because we wouldn’t have to worry about consumer acceptance,” says Ricke Kress, president of Southern Gardens Citrus,  one of the country’s largest orange juice companies with over 1.8 million trees in groves around Clewiston, FL. “It’d be the logical way to go. But the bacterium that causes this disease has never been cultured; we don’t know how to grow it to kill it.”

The industry research with genetic engineering focuses on a spinach gene that is already in the food supply. That project is being conducted by Texas A&M, in part because of work the university had already done with canker, another disease hurting the juice industry.

The spinach gene, when genetically inserted into an infected tree, causes the cell wall of the bacteria to break down so the bacteria can’t grow. In theory, the tree would be safe from the bacteria. “It could also have benefits against canker, but we don’t know that yet,” says Kress. “The proof is when we move it from the lab to the field.”

The tiny Asian citrus psyllid at 4 millimeters long is creating huge problems for the U.S. citrus industry. (Photo: David Hall, USDA Agricultural Research Service,

The company has had trees with the spinach gene in the ground and in greenhouses under various levels of testing since 2009. “So far we’ve seen variations with promise and some without,” Kress says. “We take the ones that look promising and go back to A&M and say, ‘Let’s keep working and improving.’ ”

Experimental trees in the company’s fields are under USDA-approved permits. The company received an experimental use permit from EPA to plant more acreage beyond the usual 10-acre trial limits.

Researchers are also working on a process that would carry the disease-fighting spinach gene into the tree through inoculation. “That could be more consumer-friendly because with this technology we’re not modifying the genomic structure of the tree,” says Kress. “Using the virus as a vector has the most short-term potential for disease-free trees, but the genetic engineering of the tree itself has the best long-term potential.”

Related: Citrus disease proposal gets top research spot

Inoculation requires grafting bud wood off the genetically modified “mother” tree onto other trees. That process requires an experimental use permit, which is scheduled for approval this September.

Will consumers drink GMO orange juice?


‘Necessary’ tech

If the spinach gene works and saves the orange groves, will consumers still drink GMO orange juice? Millions of dollars — and an entire food sector — ride on the answer, which Kress believes will be a yes.

“When you look at biotechnology in the food supply today, you have ‘nice’ vs. ‘necessary,’ ” he says. ‘The nice technology is, say, better weed control; the necessary technology is, if we don’t solve this issue, we may not have orange juice anymore.”

Another factor that could weigh on consumer acceptance is alternative control. “Without biotech, our only other solution is a variety of chemicals,” he says. “With the genetically modified citrus tree that will eventually be used, we have a significant reduction in chemicals, which will help the environment.”

About 85% of processed food today contains some form of genetically modified ingredients. Even so, consumers don’t fully understand where food comes from. And that’s the biggest concern — not just for orange growers, but also the food industry in general.

“We’re spoiled, but we’ve gotta figure it out,” says Kress, who believes consumers will be more informed by the time a transgenic orange tree makes its commercial debut. “We can’t feed this country on organic. We’re going to have to figure out how to use science in order to feed the world. As we work through this technology with government agencies, we’ve learned what we have to do, and they’re working with us. We’re doing it the right way to make sure it is safe.”

Southern Gardens Citrus, a subsidiary of U.S. Sugar, may be one of the few companies with the financial means to develop a tree that can beat citrus greening. If it does, the company will have exclusive rights to the technology. Even so, “we have made it clear from day one on all our research that this technology will be shared with the industry as a license,” says Kress. “We’re not going to keep it all to ourselves.”

With regulatory approvals and in-field success, some of Southern Gardens Citrus’ biotech trees may be making juice within three years or so. It may take 10 years before such trees repopulate groves on a commercial scale, assuming GMO juice is accepted in the marketplace. Meanwhile, the industry is focusing on bridge solutions, such as bactericides, to address tree decline and keep growers in business.

“There’s a strong awareness of our research, but we’ve done that by design,” Kress concludes. “We want everyone to understand: This disease is a challenge, and biotech could be an answer.”

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