Transcriptome Analysis Of Citrus Psyllid And The Study Of Its Interaction With The Huanglongbing Pathogen

Huanglongbing (HLB) is the most destructive citrus pathosystem worldwide, which is caused by the Candidatus liberibacter bacteria mostly transmitted by citrus psyllid, Diaphorina citri or Trioza erytreae. However, little is known about the mechanisms of transmission and interaction between the insect host and pathogen. Herein, we performed some researches about refered questions of D. citri and the pathogen Candidatus Liberibacter asiaticus (CaLas). The main results we concluded are listed as follows:(1) The geographic populations of citrus psyllids that were sampled from Hainan and Fujian provinces contained commonly dominant endosymbionts, including a-Proteobacteria, Wolbachia spp., Candidatus Carsonella ruddii DC and Candidatus Profftella armature. (2) The acquisition efficiency of adult citrus psyllid reached a peak at 28 days after raring on the CaLas-infected Citrus reticulata cv. Tankan. (3) The HLB pathogen could be initially detected from the orange tree, Citrus reticulata cv. Subcompressa, at 53 days after the CaLas-infected citrus psyllids biting. And, it took 75 days for the plant to be systemically infected. (4) We prepared four polyclonal antibodies against three membrane proteins. (5) We constructed a high-quality yeast two-hybrid cDNA library of D. citri, and screened the interacting proteins between the insect host and pathogen preliminary. (6) Through next-generation high-throughput DNA sequencing techniques, we firstly assembled the transcirptome of D. citri. And we further characterized genes involved into innate immune system, RNAi, P450s, CCEs, GSTs, OBPs and CSPs by comparing the datas to other insects. (7) By analyzing the expression profile datas of uninfected-adults and infected-ones, we found that 571 genes were significantly regulated by the HLB pathogen. Among them,476 genes were up-regulated, and 95 genes were down-regulated. This study can provide important theoretical bases for exploring the mechanisms of transmission and interaction between insect and pathogen.