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Open Access Highly Accessed Research article

Cloning, ligand-binding, and temporal expression of ecdysteroid receptors in the diamondback moth, Plutella xylostella

Baozhen Tang1, Wei Dong12, Pei Liang1*, Xuguo Zhou3* and Xiwu Gao1

Author affiliations

1 Department of Entomology, China Agricultural University, Beijing 100193, China

2 Inner Mongolia Prataculture Research Center, Chinese Academy of Sciences, Hohhot, 010031, China

3 Department of Entomology, University of Kentucky, Lexington, KY 40546-0091, USA

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Citation and License

BMC Molecular Biology 2012, 13:32  doi:10.1186/1471-2199-13-32

Published: 19 October 2012

Abstract

Background

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a devastating pest of cruciferous crops worldwide, and has developed resistance to a wide range of insecticides, including diacylhydrazine-based ecdysone agonists, a highly selective group of molt-accelerating biopesticides targeting the ecdysone receptors.

Result

In this study, we cloned and characterized the ecdysone receptors from P. xylostella, including the two isoforms of EcR and a USP. Sequence comparison and phylogenetic analysis showed striking conservations among insect ecdysone receptors, especially between P. xylostella and other lepidopterans. The binding affinity of ecdysteroids to in vitro-translated receptor proteins indicated that PxEcRB isoform bound specifically to ponasterone A, and the binding affinity was enhanced by co-incubation with PxUSP (Kd =3.0±1.7 nM). In contrast, PxEcRA did not bind to ponasterone A, even in the presence of PxUSP. The expression of PxEcRB were consistently higher than that of PxEcRA across each and every developmental stage, while the pattern of PxUSP expression is more or less ubiquitous.

Conclusions

Target site insensitivity, in which the altered binding of insecticides (ecdysone agonists) to their targets (ecdysone receptors) leads to an adaptive response (resistance), is one of the underlying mechanisms of diacylhydrazine resistance. Given the distinct differences at expression level and the ligand-binding capacity, we hypothesis that PxEcRB is the ecdysone receptor that controls the remodeling events during metamorphosis. More importantly, PxEcRB is the potential target site which is modified in the ecdysone agonist-resistant P. xylostella.

Keywords:
Plutella xylostella, Ecdysone receptor (EcR); Binding affinity, Expression profiling, Ecdysone agonist