Asian citrus psyllid viral pathogen

Authors: Hunter, Wayne; Hert, Mizuri

Submitted to: Georgia Academy of Sciences Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2009
Publication Date: 4/3/2009
Citation: Hunter, W.B., Hert, M.M. 2009. Asian citrus psyllid viral pathogen [abstract]. Georgia Academy of Sciences Meeting. Paper No. 67.

Interpretive Summary: A newly discovered viral pathogen of Asian citrus psyllid was classified as a Reoviridae. This virus may serve as a biological control agent for the psyllid. The psyllid is an efficient vector of the plant-infecting bacterium associated with the disease huanglongbing, which has caused extensive economic losses to citrus industries world-wide. We produced a DNA expression library prepared from adult psyllids in search of new pathogens that could be used as biological control agents. We identified two viral sequences within this DNA library. Each sequence was significant similar to the insect Reoviruses. The virus was named Diaphorina citri Reovirus. To confirm the incidence of psyllids being infected by this reovirus, psyllids were collected from the field and assayed for the virus by PCR analyses with Reovirus specific primers. Psyllids collected from the field (May 2008) were ~55 percent virus positive. Virus acquisition and transmission may be occurring due to a combination of psyllid feeding and a wide host range of the Reovirus in plants. The viral sequences were most closely related to the viruses in the family Reoviridae and constitute a newly discovered member of this family.

Technical Abstract: A newly discovered viral pathogen of Asian citrus psyllid, AsCP, Diaphorina citri, Kuwayama (Psyllidae: Hemiptera) was classified as a Reoviridae. This virus may serve as a biological control agent for AsCP. The AsCP is an efficient vector of the plant-infecting bacterium (Candidatus Liberibacter asiaticus) associated with the disease Huanglongbing which has caused extensive economic losses to citrus industries world-wide. We produced an expression library prepared from adult psyllids in search of new pathogens that can be used as biological control agents. We identified two viral sequences of 616 bp and 792 bp, each with significant similarity to insect reoviruses. Multiple sequence alignments of predicted Diaphorina citri-Reo1 amino acid sequences resulted in a 48% shared identity to RNA polymerase of Nilaparvata lugens reovirus. Multiple sequence alignments of predicted Dc-Reo2 amino acid sequences resulted in a 30% shared identity to segment S2 of the NLRV, and 25% identity to a B spike structural protein- segment 3 of Fiji Disease Virus, 24 percent identity to segment S2 the Mal de Rio Cuarto virus, 25 percent identity to P4 protein of Rice black streaked dwarf virus segment 4 and 20 percent identity to an unnamed protein product of Diadromus pulchellus idnoreovirus 1. To confirm the incidence of psyllids infected by this reovirus, psyllids were collected in the field and assayed for the virus by RT-PCR with Reo2 primers. Psyllids collected from the field (May 2008) were approximately 55 percent virus positive. No immediate pathogenic effects were observed in adult psyllids. Virus acquisition and transmission may be occurring due to a combination of the psyllid feeding behavior and wide host range of Reovirus host plants. The virus was also determined to consist of subgenomic strands similar to members of Fijivirus. Phylogenetic and homology comparisons, using PAUP 4.0 and NCBI software, indicated that the viral sequences were most closely related to the viruses in the Family Reoviridae, Genus Fijivirus, specifically Nilaparvata lugens reovirus.