Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/17/2012
Publication Date: 11/16/2012
Citation: Saha, S., Hunter, W.B., Reese, J., Morgan, J.K., Hert, M.M., Huang, H., Lindeberg, M. 2012. Survey of endosymbionts in the Diaphorina citri metagenome and assembly of a Wolbachia wDi draft genome. PLoS One 7(11): e50067 Interpretive Summary: Sequencing of the nucleic acids isolated from psyllids enabled the identification of the microbes which live inside the Asian citrus psyllid, Diaphorina citri (Hemiptera). This psyllid is spreading the devastating plant pathogenic bacteria, Candidatus Liberibacter asiaticus, known as citrus greening disease, or huanglongbing, which threatens citrus industries worldwide. Identification of the psyllid associated microbes opens the door to researchers to use these microbes in unique ways to reduce psyllid survival and reduce transmission of the bacteria to citrus trees. Analyses of the genetic sequences, revealed that the psyllid Wolbachia bacteria, belonged to supergroup B indicating that the Wolbachia Diaphorina strain in the Florida psyllids are distinct from Wolbachia Diaphorina identified in Chinese psyllid populations, supporting the hypothesis that the Asian citrus psyllid introduced into Florida did not originate from China, and were more closely related to the populations in middle eastern countries. Thus future efforts to identify biological control agents against this psyllid should concentrate their efforts within the Middle East.
Technical Abstract: Diaphorina citri, the Asian citrus psyllid,(Hemiptera) is the insect vector of Candidatus Liberibacter asiaticus, the presumed cause of citrus greening disease, known as huanglongbing. Sequencing of the Diaphorina citri metagenome has been initiated to gain better understanding of the biology of D. citri, and the potential roles of its bacterial endosymbionts. Endosymbionts previously identified by ribosomal DNA amplification were validated, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences in the national repository. Results of the mapping identified Wolbachia Diaphorina, and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using the complete genome sequences of four Wolbachia strains, assembled into a draft genome sequence, and the annotation assessed for the presence of features potentially involved in host interaction. Genome alignment with the complete sequences reveals membership of Wolbachia wDi in supergroup B, further supported by phylogenetic analysis of GatB and FtsZ. Phylogenies built using FtsZ and Wsp genes indicate that the Wolbachia strain in the Florida D. citri fall into the sub-clade of supergroup B, which is distinct from Wolbachia Diaphorina present in Chinese D. citri populations, supporting the hypothesis that the D. citri introduced into Florida did not originate from China, and were more closely related to the populations in middle eastern countries. Thus future efforts to identify biological control agents against this psyllid should concentrate their efforts within the Middle East.