CLas Inhibition with Antisense Oligonucleotides for Management of Citrus Greening Disease

CLas Inhibition with Antisense Oligonucleotides for Management of Citrus Greening Disease

Report Date: 07/15/2024
Project: 21-021   Year: 2023
Category: ACP Vector
Author: Kirsten Pelz-Stelinski
Sponsor: Citrus Research and Development Foundation

 Huanglongbing (HLB) is a systemic disease of citrus caused by the bacterial pathogen Candidatus Liberibacter asiaticus (CLas) that limits citrus production worldwide. CLas is an obligate bacterial pathogen that multiplies in citrus trees and in the insect vector, the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. There is no cure for HLB currently and broad-spectrum antibiotics represent one possible therapeutic against disease symptoms. Single-stranded nucleic acid analogs, 2’-deoxy-2’-Fluoro-ß-D-arabinonucleic antisense oligonucleotides (FANA ASOs), can modulate gene expression by enzymatic degradation or steric blocking of an RNA target. FANA ASOs recognize and bind to specific RNA forms, including mRNA, miRNA, and long noncoding RNA, through complementary base pairing. Injection of oxytetracycline (OTC) into mature citrus trees with HLB ameliorated symptoms of disease, increased fruit yield, and quality of juice as compared with that produced by non-injected controls. Injection of trees with FANA ASOs also reduced CLas infection but did not improve fruit yield and quality above control levels at the injection dosage tested. Reduced pathogen titers following OTC or FANA ASO injection were coincident with lower CLas acquisition and inoculation by laboratory deployed and wild-type D. citri collected from the field, respectively.Trunk injection of OTC in rotation with antimicrobial technologies like FANA ASOs may be useful in management of HLB by reducing CLas infection in trees and disrupting transmission. Future investigations should prioritize optimizing FANA ASO dosage in trees and exploring the potential of multiplex FANA ASOs that simultaneously target multiple mRNAs to enhance efficacy against CLas infection.       


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