Natural Compounds Might Fight HLB

Josh McGill HLB Management, Research

The U.S. Department of Agriculture (USDA) has awarded Florida International University (FIU) scientists $500,000 to investigate natural compounds that could suppress or even eliminate the bacteria that causes HLB. FIU Institute of Environment researcher Kateel Shetty is leading the search for an antimicrobial compound that could help citrus growers.

Florida International University Ph.D. student Jessica Dominguez first provided evidence that microorganisms could be used for HLB disease management while working on her master’s degree.

The FIU team’s theory is that if they can identify a compound that combats the bacteria in an infected tree, 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 the team 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 HLB disease management.

That early evidence indicated that expedited screening and selection of endophyte and plant derived extracts for potential antimicrobial activity against HLB’s causal bacteria is possible by using S. meliloti and L. crescensas culturable proxy organisms. The HLB causal bacteria is Candidatus Liberibacter asiaticus (CLas). Extracts from oregano, thyme and turmeric at a concentration of 1% were found to be significantly effective at reducing live CLas cell numbers. More detailed phytotoxicity studies of these extracts and their chemical components needs to be done to assess their potential for managing HLB. As for the extracts from bacterial endophytes, isolates B-9, B-24, B-25 and B-27 were found to be significantly effective at reducing live CLas cell numbers.

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. 

The FIU research is being fast-tracked with the hopes of arming citrus growers with a new tool in the battle against HLB.

Source: Florida International University