Functional Characterization of Allatostatin C (PISCF/AST) and Juvenile Hormone Acid O-Methyltransferase in Dendroctonus armandi

Yaya Sun,Hui Chen,Danyang Fu,Bin Liu,Linjun Wang

doi:10.3390/ijms23052749

Abstract

Allatostatin C (PISCF/AST) is a neuropeptide gene that affects juvenile hormone (JH) synthesis in the corpora allata. Juvenile hormone acid O-methyltransferase (JHAMT) is a key gene in the JH biosynthetic pathway. In this study, two genes encoding DaAST and DaJHAMT were cloned. Both DaAST and DaJHAMT were expressed in the larvae, pupae and adults of Chinese white pine beetle (Dendroctonus armandi), and highly expressed in the head and the gut. The expression of the two genes was induced by JH analog (JHA) methoprene and the functions of the two genes were then investigated by RNAi. Considering the role of hormones in metamorphosis, JHA significantly induced DaAST and DaJHAMT in the larval stage. DaAST knockdown in larvae, pupae and adults significantly increased the DaJHAMT mRNA levels. Moreover, knockdown of DaAST instead of DaJHAMT increased pupae mortality and the abnormal rate of emergence morphology and reduced emergence rates. However, knockdown of DaJHAMT instead of DaAST significantly reduced frontalin biosynthesis in adult males. The results showed that DaAST acts as an allatostatin and inhibits JH biosynthesis, and that JHAMT is a key regulatory enzyme for JH synthesis in the D. armandi.

Highlights

Insect juvenile hormone (JH), a multifunctional hormone secreted from the corpora allata (CA), plays a role in multiple physiological events including diapause, pheromone production, polyphenisms, growth, molting, metamorphosis and reproduction [1–7]
36.5%) to the juvenile hormone acid O-methyltransferase (JHAMT) predicted from the genomes of Nicrophorus vespilloides and Aethina tumida
To the JHAMT predicted from the genomes of Nicrophorus vespilloides and Aethina tumida

Summary

Introduction

Insect juvenile hormone (JH), a multifunctional hormone secreted from the corpora allata (CA), plays a role in multiple physiological events including diapause, pheromone production, polyphenisms, growth, molting, metamorphosis and reproduction [1–7]. The. JH biosynthetic pathway was conventionally divided into two phases: early steps (the upstream mevalonate pathway, MVAP) and late steps (the isoprene branch pathway, JHbranch) [8,9]. The early steps follow the mevalonic acid pathway to form farnesyl pyrophosphate (FPP) and involve several enzymes. Three units of Acetyl-CoA are condensed into mevalonate through three sequential steps involving acetoacetyl-CoA thiolase (AACT), 3-hydroxy-3-methylglutaryl-CoA synthase (HMG-S) and 3-Hydroxy-3methylglutaryl-CoA reductase (HMG-R). Isopentenyl diphosphate isomerase (IPPI) catalyzes the conversion of isopentenyl pyrophosphate (IPP) to dimethylallyl pyrophosphate (DMAPP); subsequently, IPP and DMAPP were condensed head-to-tail manner to produce geranyl diphosphate (GPP); this head-to-tail condensation can be repeated by the further reaction of GPP with IPP, yielding the JH precursor farnesyl diphosphate (FPP) [11]. The expressions of eight enzymes of the mevalonate pathway have been previously examined in Dendroctonus armandi [12,13]

Methods

Results

Discussion

Conclusion