Novel therapies targeting Candidatus Liberibacter asiaticus in citrus phloem using glucose-conjugated antibiotics and single-chain antibodies

Huanglongbing (HLB), a devastating citrus disease, is caused by the phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas). The disease leads to significant yield losses and economic damage worldwide. Current management strategies in Florida, United States, focus on developing genetically resistant plants and delivering antibiotics through trunk injections. However, these methods fail to effectively target the phloem, the specific environment where CLas thrives. To address this challenge, we are exploring two innovative phloem-specific approaches to combat CLas. The first involves the use of single-chain antibodies designed to specifically target CLas. These antibodies are expressed in transgenic citrus trees under a phloem-specific promoter and remain immobilized within the phloem. We have successfully generated transgenic trees and are currently assessing their effectiveness following CLas infection. The second approach focuses on enhancing the delivery of antibiotics into the phloem. By leveraging plant transport proteins and enzymatic pathways, we aim to facilitate the uptake and active loading of modified antibiotics into the phloem, ensuring direct interaction with the pathogen’s environment. Together, these phloem-targeted strategies offer promising solutions for protecting young citrus trees and treating existing infections, potentially transforming HLB management and improving citrus production in Florida.