Abstract
Chitin deacetylases (CDAs) are chitin-modifying enzymes known to play vital roles in insect metamorphosis and development. In this study, we identified and characterized a chitin deacetylase 1 gene (LsCDA1) from the cigarette beetle Lasioderma serricorne. LsCDA1 contains a 1614 bp open reading frame encoding a protein of 537 amino acids that includes domain structures typical of CDAs. LsCDA1 was mainly expressed in the late larval and late pupal stages. In larval tissues, the highest level of LsCDA1 was detected in the integument. The expression of LsCDA1 was induced by 20-hydroxyecdysone (20E) in vivo, and it was significantly suppressed by knocking down the expression of ecdysteroidogenesis genes and 20E signaling genes. RNA interference (RNAi)-aided silencing of LsCDA1 in fifth-instar larvae prevented the larval–pupal molt and caused 75% larval mortality. In the late pupal stage, depletion of LsCDA1 resulted in the inhibition of pupal growth and wing abnormalities, and the expression levels of four wing development-related genes (LsDY, LsWG, LsVG, and LsAP) were dramatically decreased. Meanwhile, the chitin contents of LsCDA1 RNAi beetles were significantly reduced, and expressions of three chitin synthesis pathway genes (LsTRE1, LsUAP1, and LsCHS1) were greatly decreased. The results suggest that LsCDA1 is indispensable for larval–pupal and pupal–adult molts, and that it is a potential target for the RNAi-based control of L. serricorne.
Highlights
Molting and metamorphosis are important aspects of insect growth, as the insect periodically sheds and replaces the rigid exoskeleton
Our results revealed that the silencing of LsCDA1 caused developmental disturbances and lethal morphological phenotypes, suggesting that LsCDA1 is critical for successful larval–pupal and pupal–adult molts
LsCDA1 was highly expressed in the integument and showed periodic expression during each molting
Summary
Molting and metamorphosis are important aspects of insect growth, as the insect periodically sheds and replaces the rigid exoskeleton. The insect cuticle is repeatedly renewed while the old cuticle is digested, and a series of enzymes and cofactors function in the process of molting and development [1,2]. CDAs enzymatically alter chitin by a deacetylating process, whereas CHTs and NAGs degrade chitin by hydrolyzation [6,7]. These three enzymes mainly function in insect growth and development. Studies in Nilaparvata lugens revealed that one NAG, five CHTs, and three CDAs participate in chitin degradation and are critical for nymph molting [8,9,10]
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