Abstract: 【Aim】 Molecular characterization and functional analysis of chitin deacetylase 1 gene in Oxya chinensis were conducted so as to provide the insight into novel target identification for pest management. 【Methods】 CDA-like gene fragments were obtained from an O. chinensis transcriptome database and the sequences of these fragments were analyzed by bioinformatics and homology analysis methods. A full-length cDNA sequence of OcCDA1 was obtained by rapid-amplification of cDNA ends (RACE). Real-time quantitative PCR (qPCR) was applied to detect the relative expression levels of OcCDA1 in different tissues of the 5th instar nymphs and at different developmental stages. RNA interference was performed to study the function of OcCDA1 during the growth and development of O. chinensis. 【Results】 The full-length cDNA sequence of chitin deacetylase 1 gene in O. chinensis was cloned and named as OcCDA1 (GenBank accession number: KP271171) . Gene expression profiling in tissues showed that OcCDA1 was highly expressed in foregut, integument, hindgut and fat body, and the expression level of OcCDA1 was the highest in the integument of the 1st day of the 5th instar nymphs. After the 5th instar nymphs were injected with OcCDA1 dsRNA, the relative expression level of OcCDA1 in the nymphs decreased by 93.3% as compared with that in the control (injected with dsGFP). Significantly down-regulated expression of OcCDA1 resulted in reduced feeding, slow development, and high mortality (95.2%) including 38.1% nymphs died before molting and 57.1% nymphs failed to detach from the old cuticle during molting process and died eventually. 【Conclusion】 The results demonstrate that OcCDA1 plays a key role in molting process of O. chinensis, and silencing OcCDA1 may result in high mortality with feeding reduction or molting defect phenotype.

Key words: Oxya chinensis, chitin deacetylase 1, mRNA expression, functional analysis, RNA interference