A University of Florida research team is cautiously optimistic after finding a possible treatment in the lab for citrus greening, the disease that threatens to cripple the nation’s citrus industry. The new finding uses a chemical also used to treat gout in humans.
Claudio Gonzalez and Graciela Lorca led the research team 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 citrus greening bacterium, particularly with benzbromarone, which halted the bacteria in 80 percent of the infected trees’ shoots. Benzbromarone is typically used to treat gout in humans.
They expect to begin field experiments with this treatment later this year. Their research was published in late April by the online open access journal PLOS Pathogens.
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.
Citrus greening is devastating Florida’s $9 billion citrus industry. The disease has already affected millions of citrus trees in North America and could wipe out the industry in the next decade if a viable treatment is not found.
Florida growers say they desperate for a treatment that will work.
“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.
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.
Other co-authors on the paper: Christopher Gardner, a research technician in microbiology and cell science; Max Teplitski, an associate professor in soil and water science; Svetlana Folimonova, an assistant professor in plant pathology; Lora Bojilova, a research technician; Anastasia Potts, a graduate assistant; and Amanda Sarnegrim and Cheila Tamayo, undergraduate students.