ARI SHAPIRO, HOST:
If you're an orange or a person who enjoys them, we have some good news for you. Researchers are developing tools to help control citrus greening, a disease that has killed thousands of acres of orange and grapefruit trees in Florida. As NPR's Greg Allen reports, scientists have found a promising treatment in a fruit many Americans have never heard of.
GREG ALLEN, BYLINE: The Australian finger lime looks a little like a small pickle. It's just a couple inches long, grows on small trees and is gaining some popularity as an exotic fruit. What got researcher Hailing Jin interested in it isn't its taste, but that it's not affected by citrus greening.
HAILING JIN: When I heard that there are some wild citrus close relatives they show tolerance or partial resistance, then I feel like there must be some genes responsible for it.
ALLEN: In the 15 years since citrus greening first appeared in Florida, growers and researchers have scrambled for solutions. During that time, the disease has upended the industry. Production plummeted, forcing the closure of packing houses and juice processing plants. Jin, a molecular geneticist at the University of California, Riverside, discovered the gene in finger limes that makes it tolerant to the disease. It produces a natural antibiotic that kills the bacterium responsible for citrus greening. She's also developed a way to produce it in the lab. When it's injected into trees or sprayed on leaves, Jin says, the compound has a dramatic impact.
JIN: The bacteria titer is largely reduced, and the symptom - the disease symptom is also largely reduced. The new flesh, the new leaves looks very green and healthy.
ALLEN: UC Riverside has partnered with a biotech company, Invaio Sciences, to market the anti-microbial compound. Jin is hoping to start field trials soon in Florida orange groves and then get approval from federal regulators. Steven Callaham, the head of Dundee Citrus Growers, says what he's seen so far is encouraging.
STEVEN CALLAHAM: I think it still could be several years out before that particular solution could be commercialized, but it's very, very promising research. And that's just one thing of many, I think, that you're going to see coming down the line.
ALLEN: Growers and researchers have been developing new orange varieties, new root stocks and techniques like putting orchards in screened enclosures. Michael Rogers, the director of the University of Florida's Citrus Research and Education Center, says all that work is paying off. After years of declines, Rogers says Florida's citrus production is stabilizing.
MICHAEL ROGERS: When this disease first popped up in Florida, we said, OK, you know, the industry's got about 10 years, and it's going to be gone if we don't have solutions. Well, we're not gone, but it's because we have developed ways to live with citrus greening.
ALLEN: Rogers says the naturally occurring compound from the Australian finger lime is one of dozens currently being investigated. Other promising research, he says, involves gene editing to make orange trees less susceptible to the disease.
Greg Allen, NPR News, Miami.
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