ARS | Publication request: Detection of Candidatus Liberibacter asiaticus associated with huanglongbing disease in the salivary glands and alimentary canal of Diaphorina citri

Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2010
Publication Date: July 1, 2010
Citation: Ammar, E.-D., Shatters, R.G., Hall, D.G. 2010. Detection of Candidatus Liberibacter asiaticus associated with huanglongbing disease in the salivary glands and alimentary canal of Diaphorin citri. Phytopathology 100: S6.

Technical Abstract: Candidatus Liberibacter asiaticus (Las) has been strongly implicated as the causative agent of huanglongbing (HLB), or citrus greening, which is the most devastating citrus disease in Florida and other parts of the world. HLB is transmitted in a persistent manner by psyllid vectors and in the US and Asia by the Asian citrus psyllid Diaphorina citri. We used quantitative polymerase chain reaction (Q-PCR) to detect Las in dissected organs of individual D. citri adult males and females collected from HLB-infected citrus trees in Florida between August and December 2009. The mean proportion of PCR-positive organs was 13 - 24 percent for the alimentary canals, 12 - 16 percent for the salivary glands, and 16-25 percent for the rest of the insect body. Percentage of infection did not differ significantly between the three insect parts in males but was significantly lower in the salivary glands than in the alimentary canals of females. Our results provide the first PCR confirmation of Ca L. asiaticus in the alimentary canal and salivary glands of D. citri, and suggest that both organs may constitute major transmission barriers to Las in the psyllid vector. We are currently testing other techniques including TEM, immunolabeling, and in situ hybridization for the purpose of elucidating the transmission barriers and cellular interactions of Ca L. asiaticus in this economically important vector.