Endophytes as Sources of Antimicrobials to Control Huanglongbing
Posted August 2025
Researchers: Kateel Shetty, Megan Dewdney, Amir Rezazadeh, Krish Jayachandran, Diego Salazar Amoretti, Kranthi Mandadi
Contact: Kateel Shetty, Florida International University shettyk@fiu.edu
Summary:
Endophytes are those microorganisms that spend a part of their life cycle within plants without causing disease. These microorganisms are potential sources of antimicrobial compounds that could play a role in sustainable agriculture through direct action on other microorganisms or reducing plant stress or promoting plant growth and yield. These organisms can live in the vascular tissues of plants. The team evaluated the microbiome of survivor (not showing symptoms of huanglongbing (HLB) in an otherwise affected grove) citrus trees and found 4 endophytic bacteria with potential antibacterial properties. The crude extracts of these bacteria showed antibacterial properties against Liberibacter crescens, the culturable relative of Candidatus Liberibacter asiaticus (CLas) and against CLas cells present in the tissue extract taken from CLas positive psyllids. Work has been done to purify the parts of the original extracts to identify which compounds are the active ones. Fractions of the extracts with activity have been screened with the hairy root assay to see if there is activity against CLas, eliminating some fractions for further testing. Greenhouse trees (‘Valencia’ sweet orange) have been inoculated with CLas and are ready to test the active fractions in whole citrus plants, the next step in the testing process.
Take Home Message:
- Endophytic organisms are a potential source of environmentally safe antimicrobial compounds.
- Endophytic bacteria that have an anti- Liberibacter effect were identified from survivor citrus trees.
- The next step is to see if there is activity against CLas in greenhouse trees.
