A peptide that binds the Asian citrus psyllid gut reduces transmission of the citrus greening pathogen Candidatus Liberibacter asiaticus

ABSTRACT Citrus greening disease, associated with the bacterium Candidatus Liberibacter asiaticus ( C Las), has severely impacted citrus yields on a global scale. C Las is vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama, in a circulative and propagative manner. Extensive application of chemical insecticides for suppression of psyllid populations has resulted in widespread resistance. Despite considerable effort and expenditure, citrus greening disease continues to impair citrus production. For transmission to occur, C Las must bind and infect the psyllid vector via the gut epithelium, but little is known of the specific molecular interactions involved. By screening a phage display library, we selected ten psyllid gut binding peptides, a subset of which have sequence similarity to C Las surface proteins. Peptide binding to the surface of the psyllid gut epithelium was confirmed by identification of gut proteins bound by specific peptides. We evaluated whether these peptides could interfere with the interaction between C Las and the gut epithelium of D. citri , thereby impeding pathogen transmission. Peptide DcNy2 significantly reduced C Las acquisition and inoculation by D. citri compared to control treatments. Nymphs fed specific peptides exhibited reduced C Las acquisition and infection of both the alimentary canal and salivary glands without negatively impacting psyllid fecundity, development, or survival. These results support peptide-mediated disruption of C Las transmission by D. citri as a potential component of integrated strategies to manage citrus greening disease. IMPORTANCE Citrus greening disease, or huanglongbing, causes billions of dollars in losses and represents one of the greatest challenges facing global citrus production. Despite significant investment on multiple fronts, effective disease management strategies are lacking. This study shows for the first time that short peptides that bind to the surface of the gut of the Asian citrus psyllid vector interfere with C Las association with the gut. This critical first gut binding step is required for C Las to infect and propagate within the psyllid vector. The downstream consequence of this peptide-mediated interference is reduced acquisition and transmission of the citrus pathogen. This work provides the foundation for new transgenic or paratransgenic tools for use in the management of citrus greening disease.