RNA interference-mediated functional characterization of Group I chitin deacetylases in Holotrichia parallela Motschulsky

• Published in: Pesticide biochemistry and physiology Vol. 173; p. 104770
• Main Authors: Zhao, Dan, Liu, Zhao-rui, Wu, Han, Fu, Chao-ran, Li, Ya-zi, Lu, Xiu-jun, Guo, Wei
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2021
• Subjects: Amidohydrolases - genetics; Amidohydrolases - metabolism; Animals; Chitin - metabolism; Chitin deacetylase; Chitin laminae; Coleoptera - genetics; Coleoptera - metabolism; Holotrichia parallela; Insect Proteins - genetics; Insect Proteins - metabolism; RNA Interference; RNA interference; Chitin deacetylase; Holotrichia parallela; Chitin laminae
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2021.104770

Chitin deacetylases (CDAs, EC 3.5.1.41) catalyze the N-deacetylation of chitin to produce chitosan, which is essential for insect survival. Hence, CDAs are promising targets for the development of novel insecticidal drugs. In this study, the putative Group I chitin deacetylase genes HpCDA1, HpCDA2-1 and HpCDA2-2 were identified from Holotrichia parallela. Conserved domain database search identified a chitin-binding peritrophin-A domain (ChBD), a low-density lipoprotein receptor class A domain (LDLa), and a putative CDA-like catalytic domain. RT-qPCR analysis showed that the Group I HpCDAs were expressed in various tissues and predominant in the integument. The developmental expression patterns from the first-instar to third-instar larvae showed that HpCDAs were highly expressed on the first day and gradually declined after molting. The functional characteristics of the Group I CDAs in cuticle organization were examined using RNA interference (RNAi) and transmission electron microscopy (TEM) methods. Administration of double-stranded HpCDA (dsHpCDA) through larval injection could suppress the expression levels of HpCDA1 and HpCDA2, thus resulting in abnormal or lethal phenotypes. TEM analysis revealed that RNAi of either HpCDA1 or HpCDA2 remarkably affected the cuticle integrity, as evidenced by cuticle disorganization and chitin laminae disruption, suggesting the crucial role of CDAs in chitin modification. These experimental results demonstrate the important contribution of putative key genes involved in chitin metabolism, and provide a foundation for developing new strategies to control H. parallela. 1. Group I chitin deacetylases is essential for the structure of cuticle of H. parallela. 2. The cuticle structure was observed after dsHpCDA injection using TEM. [Display omitted] •Molecular cloning of Group I chitin deacetylases in H. parallela.•RNAi of HpCDAs resulting in abnormal or lethal phenotypes of the larvae.•TEM analysis revealed that RNAi of HpCDAs remarkably affected the cuticle integrity.•The Group I HpCDAs play a crucial role during insect development.