Canadian Forest Service Publications
Characterization of a spruce budworm chitin deacetylase gene: stage-and tissue-specific expression, and inhibition using RNA interference. 2013. Quan, G.; Ladd, T.; Duan, J.; Wen, F.; Doucet, D.; Cusson, M.; Krell, P.J. Insect Biochemistry and Molecular Biology 43:683-691.
Issued by: Great Lakes Forestry Centre
Catalog ID: 34915
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Chitin deacetylase (CDA) catalyzes the conversion of chitin into chitosan, thereby modifying the physical properties of insect cuticles and peritrophic matrices. A lepidopteran chitin deacetylase gene (CfCDA2) was cloned from the spruce budworm, Choristoneura fumiferana, and found to generate two alternatively spliced transcripts, CfCDA2a and CfCDA2b. Transcriptional analysis using isoform-specific RT-PCR primers indicated that both isoforms were upregulated during the molt. Interestingly, CfCDA2b transcripts were most abundant in the head during the molting stage while those of CfCDA2a were predominant in the epidermis during the feeding period. Injection of CfCDA2-specific dsRNA into C. fumiferana larvae or pre-pupae induced both abnormal phenotypes and high mortality, which resulted from an inability to shed the old cuticle. These results suggest that CfCDA2 plays an important role in the molting process, and that the two alternatively spliced transcripts have different functions during insect development. This is the first detailed characterization of lepidopteran chitin deacetylase gene.
Plain Language Summary
To grow, insects must undergo periodic molts during which they shed their old cuticle (skin) and acquire a new, larger one. Disruption of this process can kill pest insects. We identified and characterized a cuticle modification gene from the spruce budworm that can modify the physical properties of insect cuticles. We found that introducing the gene corresponding to double stranded RNA into larvae or pre-pupae created an inability to shed the old cuticle, which caused both abnormal body shapes and high mortality. This process is called RNA interference (RNAi), which has become an important tool for studying gene function in animals, plants and insects. This technology has been used to develop safer and more environmentally friendly pesticides. However, less successful examples have been reported from lepidopteran (such as the spruce budworm) insects. We were the first group to confirm that RNAi works in the spruce budworm and we found that the cuticle modification gene might be a good target to develop RNAi-based pesticides.