Lessons learned about the biology and genomics of Diaphorina citri infection with "Candidatus Liberibacter asiaticus" by integrating new and archived organ-specific transcriptome data.

Background: Huanglongbing, a devastating disease of citrus, is caused by the obligate, intracellular bacterium "Candidatus Liberibacter asiaticus" (CLas). CLas is transmitted by Diaphorina citri, the Asian citrus psyllid. Development of transmission-blocking strategies to manage huanglongbing relies on knowledge of CLas and D. citri interactions at the molecular level. Prior transcriptome analyses of D. citri point to changes in psyllid biology due to CLas infection but have been hampered by incomplete versions of the D. citri genome, proper host plant controls, and/or a lack of a uniform data analysis approach. In this work, we present lessons learned from a quantitative transcriptome analysis of excised heads, salivary glands, midguts, and bacteriomes from CLas-positive and CLas-negative D. citri using the chromosomal length D. citri genome assembly.

Results: Each organ had a unique transcriptome profile and response to CLas infection. Though most psyllids were infected with the bacterium, CLas-derived transcripts were not detected in all organs. By analyzing the midgut dataset using both the Diaci_v1.1 and v3.0 D. citri genomes, we showed that improved genome assembly led to significant and quantifiable differences in RNA-sequencing data interpretation.

Conclusions: Our results support the hypothesis that future transcriptome studies on circulative, vector-borne pathogens should be conducted at the tissue-specific level using complete, chromosomal-length genome assemblies for the most accurate understanding of pathogen-induced changes in vector gene expression.