Dou, Wei

AbstractBACKGROUNDAlthough it is known that Candidatus Liberibacter asiaticus (CLas), the agent of citrus Huanglongbing, circulates and multiplies within the insect vector Diaphorina citri, the specific factors enabling CLas transmission remain unclear. Previous studies have shown that ATPSyn‐β facilitates phytoplasma movement in vector insects, and functions as a transport protein in D. citri. In this study, the role of ATPSyn‐β was expected to be unveiled in CLas transmission in D. citri.RESULTSThe interaction between ATPSyn‐β of D. citri and the outer membrane protein A (OmpA) of CLas was identified using glutathione S‐transferase pull‐down and yeast two‐hybrid assays. No interactions existed between OmpA and vitellogenin (Vg). Bioinformatics analysis revealed that ATPSyn‐β contained two conserved domains, ATP‐synt_ab_N and ATP‐synt_ab. Notably, ATP‐synt_ab_N interacted with both OmpA and Vg, indicating a competitive relationship between Vg and OmpA for binding to ATPSyn‐β. After silencing ATPSyn‐β expression using RNAi, the feeding behavior of D. citri decreased, resulting in a lower acquisition of CLas. Subsequently, this inhibited CLas movement within D. citri and reduced the inoculation of CLas to healthy citrus plants.CONCLUSIONATPSyn‐β was involved in the acquisition, movement in vivo, and inoculation of CLas by interacting with OmpA, thus offering a novel target to prevent the spread of citrus Huanglongbing. © 2025 Society of Chemical Industry.

AbstractThe Asian citrus psyllid, Diaphorina citri, is the primary vector of the HLB pathogen, Candidatus Liberibacter asiaticus (CLas). The acquisition of CLas shortens the developmental period of nymphs, accelerating the emergence into adulthood and thereby facilitating the spread of CLas. Cuticular proteins (CPs) are involved in insect emergence. In this study, we investigated the molecular mechanisms underlying CLas‐promoted emergence in D. citri via CP mediation. Here, a total of 159 CP genes were first identified in the D. citri genome. Chromosomal location analysis revealed an uneven distribution of these CP genes across the 13 D. citri chromosomes. Proteomic analysis identified 54 differentially expressed CPs during D. citri emergence, with 14 CPs exhibiting significant differential expression after CLas acquisition. Five key genes, Dc18aa‐1, Dc18aa‐2, DcCPR‐24, DcCPR‐38 and DcCPR‐58, were screened from the proteome and CLas acquisition. The silencing of these 5 genes through a modified feeding method significantly reduced the emergence rate and caused various abnormal phenotypes, indicating the crucial role that these genes play in D. citri emergence. This study provides a comprehensive overview of the role of CPs in D. citri and reveals that CLas can influence the emergence process of D. citri by regulating the expression of CPs. These key CPs may serve as potential targets for future research on controlling huanglongbing (HLB) transmission.

Endosymbionts play crucial roles in various physiological activities within insect hosts. The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an important vector for Candidatus Liberibacter asiaticus (CLas), a fatal pathogenic bacterial agent causing the disease Huanglongbing in the citrus industry. This study combines high-throughput sequencing of 16S ribosomal RNA amplicons to explore how CLas affects the bacterial community in different color morphs (blue, gray), genders, and tissues (cuticle, gut, mycetome, Malpighian tubule, ovary, and testis) of ACP. We found that there was no significant differences in the bacterial community diversity and CLas acquired ratio between the different color morphs and genders of ACP adults. However, acquiring CLas could promote the adult bacterial community’s diversity and richness more than in the uninfected condition. The presence of CLas could increase the Wolbachia and unclassified_Enterobacteriaceae proportions more than in the uninfected condition. The bacterial community diversity in the CLas infected tissues of ovary and cuticle, was lower than the uninfected condition, but the richness of all tissues was not different between the infected and uninfected conditions. CLas could also change the bacterial structure in different tissues and make the bacterial relationship network simpler than it is in an uninfected condition. Furthermore, we used quantitative real-time PCR to assess the dynamic changes of Wolbachia in CLas uninfected and infected color morphs and tissues of ACP. The results showed that Wolbachia titers were significantly higher in CLas infected adults than in uninfected adults. In different tissues, the Wolbachia titers in the testis, ovary, and Malpighian tubule were higher than their uninfected counterparts. Our results provide essential knowledge for understanding the symbionts of the ACP and how CLas affects the bacterial community of the ACP.