Suppression of Gene Juvenile Hormone Diol Kinase Delays Pupation in Heortia vitessoides Moore.

Zihao Lyu,Jie Cheng,Jingxiang Chen,Tong Lin,Zhixing Li,Chunyan Wang

doi:10.3390/insects10090278

Abstract

Juvenile hormone diol kinase (JHDK) is a critical enzyme involved in juvenile hormone degradation in insects. In this study, HvJHDK in the Heortia vitessoides Moore (Lepidoptera: Crambidae) transcriptional library was cloned. Stage-specific expression patterns of HvJHDK, HvJHEH, and HvJHE as well as juvenile hormone titers were determined. The three tested enzymes participated in juvenile hormone degradation. Moreover, juvenile hormone titers peaked after larval–larval molts, consistent with a role for juvenile hormone in inhibition of metamorphosis. HvJHDK was subsequently suppressed using RNA interference (RNAi) to reveal its functions. Different concentrations of dsJHDK elicited the optimal interference efficiency at different life stages of H. vitessoides. Suppression of HvJHDK decreased HvJHDK content and increased the juvenile hormone titer, thereby resulting in reduced triglyceride content, sharply declined survival rate, clearly lethal phenotypes, and extended larval growth. Moreover, suppression of HvJHDK upregulated HvJHEH and HvJHE expression levels, suggesting that there is feedback regulation in the juvenile hormone metabolic pathway. Taken together, our findings provide molecular references for the selection of novel insecticidal targets.

Highlights

Juvenile hormone (JH) is one of the most important insect hormones
Thissequence sequence was long encoded a anddesignated designated as HvJHDK
Our findings suggest that the JH degradation pathway mediated by HvJHDK promotes lipid accumulation in both the larval and the pupal stages of H. vitessoides, and suppression of HvJHDK restrains accumulation of TG content

Summary

Introduction

Juvenile hormone (JH) is one of the most important insect hormones. This unique sesquiterpenoid hormone is crucial for various physiological processes in insects, including embryonic development, metamorphosis regulation, imaginal disc formation, sexual maturation, reproduction, pheromone production, and nutrition [1,2,3,4,5]. Juvenile hormone esterase (JHE; EC 3.1.1.1) [12], juvenile hormone epoxide hydrolase (JHEH; EC 3.3.2.3) [13], and juvenile hormone diol kinase (JHDK; EC 2.1.7.3) [14], catalyze JH metabolism [15]. JHE converts JH to JH acid (JHa) via methyl ester hydrolysis, and JHEH hydrolyzes the JH epoxide moiety to produce JH diol (JHd). JHE catalyzes JHd, and JHEH degrades JHa to produce JH acid diol (JHad) [13]

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Discussion

Conclusion