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.

There was not enough evidence to prove that ICE was present in embryos derived from both rcp and RT translocation carriers, regardless of the maternal age. However, chromosomal numerical abnormalities were noticed in 23 pairs of autosomes and sex chromosomes in parental structurally normal chromosomes. Thus, 24-chromosomal analysis with an aCGH/SNP microarray PGD protocol is required to decrease the risks of failure to diagnose aneuploidy in structurally normal chromosomes.

Chitin deacetylase (CDA) is a chitin degradation enzyme that strictly catalyzes the deacetylation of chitin to form chitosan, which plays an important role in regulating growth and development, as well as the immune response. In this study, a chitin deacetylase 3 gene (CDA3) was identified with a complete open reading frame (ORF) of 1362 bp from the genome database of Diaphorina citri, encoding a protein of 453 amino acids. Spatiotemporal expression analysis suggested that D. citri CDA3 (DcCDA3) had the highest expression level in the integument and third-instar nymph stage. Furthermore, DcCDA3 expression level can be induced by 20-hydroxyecdysone (20E). Injection of Escherichia coli and Staphylococcus aureus induced the upregulation of DcCDA3 in the midgut, while DcCDA3 was downregulated in the fat body. After silencing DcCDA3 by RNA interference, there was no influence on the D. citri phenotype. In addition, bactericidal tests showed that recombinant DcCDA3 inhibited gram-positive bacteria, including S. aureus and Bacillus subtilis (B. subtilis). In conclusion, our results suggest that DcCDA3 might play an important role in the immune response of D. citri.

Chitin is one the main components of the insect cuticle, and chitin synthase (CHS) is an important enzyme required for chitin formation. CHS has been characterized in various insect species, but the structure and biochemical properties in Spodoptera litura have not been determined. In this study, we identified two CHS genes, SlCHS1 and SlCHS2, which encode proteins with 1565 and 1520 amino acid residues, respectively. Transcriptional analysis suggested that SlCHS1 has a high expression level in the integument whereas SlCHS2 showed the highest expression level in the midgut. During S. litura growth and development, SlCHS1 and SlCHS2 were both predominantly expressed in the fourth-instar larval stage. In addition, the expression of SlCHS1 and SlCHS2 could be induced by 20-hydroxyecdysone (20E). Silencing of SlCHS1 by RNA interference significantly inhibited the pupation and molting of S. litura larvae (RNAi), while knockdown of SlCHS2 had no significant effects on the S. litura phenotype. These results may provide a new molecular target for control of S. litura.

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