Abstract
The pea aphid, Acyrthosiphon pisum, is an important agricultural pest and an ideal model organism for various studies. Chitin synthase (CHS) catalyses chitin synthesis, a critical structural component of insect exoskeletons. Here, we identified a CHS gene from A. pisum, ApisCHS. The ApisCHS expression profiles showed that ApisCHS was expressed in various developmental stages and in all tested tissues of A. pisum, including the epidermis, embryo, gut and haemolymph. Notably, ApisCHS exhibited peak expression in the middle of each nymphal period and was extremely highly expressed in the epidermis and embryo. RNA interference (RNAi) showed that ~600 ng of dsRNA is an effective dose for gene silencing by injection for dsRNA delivery; moreover, 1200 ng·μL−1 dsRNA induced CHS gene silencing by a plant-mediated feeding approach. A 44.7% mortality rate and a 51.3% moulting rate were observed 72 h after injection of dsApisCHS into fourth-instar nymphs, compared with the levels in the control (injected with dsGFP). Moreover, a longer period was required for nymph development and a 44.2% deformity rate among newborn nymphs was obtained upon ingestion of dsApisCHS. These results suggest that ApisCHS plays a critical role in nymphal growth and embryonic development in pea aphids, and is a potential target for RNAi-based aphid pest control.
Highlights
The exoskeleton of insects consists of cuticles and plays a variety of functional roles, including in protection, support, movement and acting as a shield against environmental stresses[1]
In terms of temporal expression, ApisCHS was analysed in different developmental stages
We hypothesised that ApisCHS may be involved in aphid development and embryonic development
Summary
The exoskeleton of insects consists of cuticles and plays a variety of functional roles, including in protection, support, movement and acting as a shield against environmental stresses[1]. Exoskeletons with a rigid structure have limitations regarding the growth and development of insects To overcome this problem, insects periodically form a new cuticle to replace the old one, in which chitin plays a key role[1]. RNA interference (RNAi) is a powerful tool to study gene function in various organisms through the delivery of gene-specific double-stranded RNA (dsRNA); it is recognised as a next-generation approach for insect pest control[23,24]. In insects, both viral infections[25,26] and nonspecific exogenous dsRNA27,28 can induce activity of the siRNA pathway. The current study could deepen our understanding of the role of CHS in aphid growth as well as embryonic development, which should guide further studies to develop this gene as a candidate for RNAi-based control of the pea aphid and other aphids
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