1st Place: Antisense oligonucleotides as a novel tool for reducing Candidatus Liberibacter asiaticus acquisition by Diaphorina citri Kuwayama (Hemiptera: Liviidae) in citrus groves

Citrus greening, caused by the bacterial pathogen Candidatus Liberibacter asiaticus (CLas), has decimated the Florida citrus industry since its discovery in 2005. CLas is an obligate bacterial pathogen that multiplies in citrus trees and in the insect vector, the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. It is currently not possible to treat trees infected with CLas. Management of citrus greening disease, or Huanglongbing (HLB), has relied heavily on infected tree removal, insecticidal management of the ACP vector, and broad-spectrum antibiotic treatments. These inputs are not sustainable due to the large number of infected trees, high costs of replanting and insecticides, and the development of insecticide resistance. FANA ASOs are chemically modified synthetic single-stranded nucleic acid analogs that can modulate gene expression by enzymatic degradation or steric blocking of an RNA target. This study investigated the use of FANA oligonucleotides to reduce existing CLas infections and prevent the acquisition of CLas by ACP. We hypothesized that FANA oligonucleotides targeting CLas would silence CLas genes in infected hosts, thereby reducing the titer of CLas in infected trees and decreasing acquisition by ACP. The implications of these findings are discussed with respect to improving tree health in citrus groves and providing a more sustainable approach for the management of HLB.