Scientists believe weapon against citrus greening already exists in nature

Researchers are turning to a plant’s own microbiome to fight the destruction of citrus greening on Florida’s citrus trees.

The U.S. Department of Agriculture has awarded FIU scientists $500,000 to investigate natural compounds that could suppress or even eliminate the deadly bacteria that causes citrus greening. Currently, no cure exists for this disease that has left its mark on Florida’s citrus production, causing more than a 70% reduction in orange crops since first appearing in the state in 2005. FIU Institute of Environment researcher Kateel Shetty is leading this search for an antimicrobial compound that could help citrus growers gain control over this bacterial scourge.

“The bacteria inside an infected citrus plant needs to be killed or its population significantly reduced to minimize the symptoms and help the tree to survive,” said Shetty, an associate professor of agroecology in the Department of Earth and Environment.

Also known as Huanglongbing, citrus greening is spread by a tiny invasive insect from Asia. Infected trees produce fruits that are green, misshapen, bitter and unsuitable for sale as fresh fruit or for juice. Most infected trees die within a few years. Though it poses no threat to the health of people or animals, it can destroy entire citrus orchards.

If they can identify a compound that combats the bacteria in an infected tree, the team's theory is that the tree will thrive and be a productive fruit producer. It could also slow or even stop the spread of the disease to other trees. Shetty believes they may be able to identify a natural compound because of preliminary findings from one of his current Ph.D. students while she was working on her master’s degree at FIU in 2019. Jessica Dominguez provided early evidence that microorganisms called endophytes could be used for disease management in citrus greening. Essentially, they hope to fight bad bacteria with good bacteria.

Shetty is working with fellow agroecology researcher Krish Jayachandran and biologist Diego Salazar Amoretti as well as researchers from Texas A&M University and University of Florida to advance this work. The two-year USDA grant is funded as part of the National Institute of Food and Agriculture Emergency Citrus Disease Research and Extension program, which brings top scientists together with citrus industry representatives to find scientifically sound solutions to combat and prevent citrus greening at the farm-level. 

Today, citrus greening is found in all of Florida’s citrus-producing counties and has spread throughout the U.S. including Texas and California. It does not discriminate and will attack any type of citrus tree including orange, lemon, lime and grapefruit. The FIU research is being fast-tracked with the hopes of arming citrus growers with a new tool in the battle against this devastating disease.