Vesicular transport-related genes in Diaphorina citri are involved in the process of Candidatus Liberibacter asiaticus infection

Asian citrus psyllid (ACP, Diaphorina citri) is the major vector of Candidatus Liberibacter asiaticus (CLas), which is a bacterial pathogen causing the devastating citrus Huanglongbing (HLB) disease. Diaphorina citri is known to carry CLas in a persistent and propagative manner. Some studies have suggested that CLas may use the vesicular structures of D. citri cells as its propagation organelles. However, the mechanisms by which CLas enters the D. citri cells and how vesicle-mediated trafficking is involved remain unclear. In this study, we monitored the titer change of CLas in D. citri nymphs during the process of CLas acquisition from feeding on infected citrus plants. We found that the titer of CLas increased with the acquisition access period. After infection, there was a significant upregulation in the expression of several vesicular transport-related genes in D. citri. The titer of CLas was significantly reduced in the midgut and whole insect body when endocytosis and the endosome network in D. citri were inhibited. Furthermore, silencing the D. citri clathrin-heavy chain gene also led to a reduction in the CLas titer in D. citri. These results suggest that CLas infection upregulates the genes related to vesicular transport in D. citri, which facilitates the invasion of endocytosis-dependent pathogens.