Researchers Find Chemicals To Treat Citrus Greening In The Lab

Researchers Find Chemicals To Treat Citrus Greening In The Lab

A University of Florida (UF) research team is cautiously optimistic after finding a possible treatment in the lab for citrus greening. It is the first step in a years-long process to bring a treatment to market.


Claudio Gonzalez and Graciela Lorca led the research team at UF that examined three biochemical treatments: phloretin, hexestrol, and benzbromarone.

The team sprayed greenhouse tree shoots separately with one of the three biochemicals and were successful in stopping the bacteria’s spread, particularly with benzbromarone, which halted the bacteria in 80% of the infected trees’ shoots. They expect to begin field experiments with this treatment later this year. Their research was recently published by the online open-access journal PLOS Pathogen.

Gonzalez and Lorca are associate professors in the UF/IFAS Microbiology and Cell Science Department. The team also works under the auspices of the UF Genetics Institute.

The researchers found that benzbromarone targets a specific protein, known as LdtR, in the citrus greening bacterium. When benzbromarone binds to LdtR, it inactivates the protein, which disrupts a cell wall remodeling process critical for the greening bacterium’s survival inside a citrus tree.

“As a consequence of the chemical treatment, several genes were not expressed and the bacteria were not able to survive inside the phloem of the plant where osmotic pressure from sugar is high,” said Fernando Pagliai, a co-author of the study and a UF graduate assistant. Phloem is the living tissue that carries organic nutrients to all parts of the plant.

Benzbromarone is typically used to treat gout in humans.

Florida growers say they are excited at the prospect of a possible treatment but desperate for one as soon as possible. “Every grower I know is just hanging by their fingernails, hoping and praying for a new discovery for treatment,” said Ellis Hunt Jr. of Lake Wales, whose family has been in the citrus business since 1922. “Most growers would be willing to try this in their groves now if it’s truly showing promising results.”

Industry experts, though, say it could be five to seven years before a new active-ingredient product could be commercially available because of the amount of time field testing takes and government regulations.

Jackie Burns, director of the UF/IFAS Citrus Research and Education Center in Lake Alfred, said because of those regulations, which are meant to ensure a safe food supply, researchers can’t accelerate testing and approval. And she noted that although the initial results of the research are promising, there is no guarantee the compounds will work under field conditions.