Silencing of the Chitin Synthase Gene Is Lethal to the Asian Citrus Psyllid, Diaphorina citri

Abstract

Chitin synthase is a critical enzyme that catalyzes N-acetylglucosamine to form chitin, which plays an important role in the growth and development of insects. In this study, we identified a chitin synthase gene (CHS) with a complete open reading frame (ORF) of 3180 bp from the genome database of Diaphorina citri, encoding a protein of 1059 amino acid residues with the appropriate signature motifs (EDR and QRRRW). Reverse transcription-quantitative PCR (RT-qPCR) analysis suggested that D. citri CHS (DcCHS) was expressed throughout all developmental stages and all tissues. DcCHS had the highest expression level in the integument and fifth-instar nymph stage. Furthermore, the effects of diflubenzuron (DFB) on D. citri mortality and DcCHS expression level were investigated using fifth-instar nymph through leaf dip bioassay, and the results revealed that the nymph exposed to DFB had the highest mortality compared with control group (Triton-100). Silencing of DcCHS by RNA interference resulted in malformed phenotypes and increased mortality with decreased molting rate. In addition, transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH) also revealed corresponding ultrastructural defects. Our results suggest that DcCHS might play an important role in the development of D. citri and can be used as a potential target for psyllid control.

Knockdown of the Trehalose-6-Phosphate Synthase Gene Using RNA Interference Inhibits Synthesis of Trehalose and Increases Lethality Rate in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)

“…Many previous research reports have demonstrated the feasibility of RNAi through feeding [8,11,21,30]. Our results have shown that feeding-based RNAi of the DcTPS gene can specifically restrain the expression of the DcTPS gene and significantly affects nymphal growth and development in D. citri, leading to increased mortality and deformity.…”

“…Therefore, there are some negative effects on the growth of nymphs and adults which cause even higher mortality and malformation in D. citri following the knockdown of the DcTPS gene. These results suggest that RNAi technology could be used for in-field control of D. citri [8].…”

“…In addition, D. citri serves as the only vector of the bacterium Candidatus Liberbacter asiaticus, which is responsible for outbreaks of "huanglongbing (HLB)", and seriously affects economic development in the citrus industry [2,[5][6][7]. Therefore, the control of D. citri plays a crucial role in preventing HLB from spreading [8]. Previous studies in China have shown that reduction of D. citri populations depended on the widespread application of insecticides [2,9,10].…”

“…RNA interference (RNAi) is a method for posttranscriptional gene silencing that has become a popular tool for exploring the function of genes in various insects [8]. Studies have shown that methods of transporting double-stranded RNA (dsRNA) into organisms mainly include microinjection, soaking, oral feeding and transgenic plant expression [14][15][16].…”

“…Additionally, silencing the TPS gene of Tribolium castaneum resulted in malformation and an increased mortality rate; chitin metabolism of T. castaneum was also affected [22]. The efficacy of different dsRNA delivery methods varies with the target genes [8]. Microinjection is considered the most efficient means of knocking down target genes [23,24].…”