Identification and Functional Analysis of Two Chitin Synthase Genes in the Common Cutworm, Spodoptera litura

Abstract

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.

Identification and Functional Characterization of Two Chitin Synthases in the Black Cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

“…The open reading frames of AiCHS1 and AiCHS2 were 4,701 and 4,629 bp, respectively, in length, which were in line with other chitin synthases (Bansal et al 2012, Shao et al 2020, Yu et al 2020). Based on the sequence alignment, the catalytic domain shared >90% amino acid identity with other Lepidoptera insects (Fig.…”

“…In A. ipsilon (this study), AiCHS1 has 16-17, and AiCHS2 has 16 transmembrane regions. In G. pyloalis, both chitin synthases have 13 (Shao et al 2020), in S. litura chitin synthases contain 16 (Yu et al 2020), while CHS1 in the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), has 14 transmembrane regions (Lu et al 2019).…”

RNAi Efficiency through dsRNA Injection Is Enhanced by Knockdown of dsRNA Nucleases in the Fall Webworm, Hyphantria cunea (Lepidoptera: Arctiidae)

“…In general, dsRNAs are more likely to elicit an RNAi response when delivered by injection rather than through feeding [ 15 , 16 ]. However, it is difficult to achieve an effective RNAi response by dsRNA injection in H. cunea compared with other lepidopterans: for example, 1 μg dsRNA of IIS (insulin/insulin-like growth factor signaling) genes was needed in Maruca vitrata , 3 μg dsRNA of TPS (trehalose-6-phosphate synthase) gene was needed in Heortia vitessoides , and 5 μg dsRNA of CHS (chitin synthase) gene was needed in S. litura , whereas H. cunea required 10 μg dsRNA injection for effective silencing of chitin deacetylase ( CDA ) genes [ 17 , 18 , 19 , 20 ]. Our previous work also showed that RNAi via dsRNA injection has a rather modest effect on H. cunea larvae.…”

Transcriptomics and Metagenomics of Common Cutworm (Spodoptera Litura) and Fall Armyworm (Spodoptera Frugiperda) Reveal Their Differences on Detoxification and Development

“…We supposed that the enriched terms of chitin metabolism not only associated with metamorphosis, but also could bene t to construct tougher cuticles and provide chemical and biological protection in the chrysalis stage of S. litura. This helps us to develop speci c insecticides that target genes related the metabolism of chitin [27]. In the adult stage, GO terms associated with reproduction were enriched, such as chorion-containing eggshell formation (GO:0007304), embryonic pattern speci cation (GO:0009880) and structural constituent of chorion (GO:0005213), which are essential to the behaviors like mating, oviposit, and incubation.…”