Development associated profiling of chitinase and microRNA of Helicoverpa armigera identified chitinase repressive microRNA

Abstract

Expression of chitinase is developmentally regulated in insects in consonance with their molting process. During the larval-larval metamorphosis in Helicoverpa armigera, chitinase gene expression varies from high to negligible. In the five-day metamorphic course of fifth-instar larvae, chitinase transcript is least abundant on third day and maximal on fifth day. MicroRNA library prepared from these highest and lowest chitinase-expressing larval stages resulted in isolation of several miRNAs. In silico analysis of sequenced miRNAs revealed three miRNAs having sequence similarity to 3′UTR of chitinase. Gene-targeted specific action of these miRNAs, was investigated by luciferase reporter having 3′UTR of chitinase. Only one of three miRNAs, miR-24, inhibited luciferase expression. Further, a day-wise in vivo quantification of miR-24 in fifth-instar larvae revealed a negative correlation with corresponding chitinase transcript abundance. The force-feeding of synthetic miR-24 induced significant morphological aberrations accompanied with arrest of molting. These miR-24 force-fed larvae revealed significantly reduced chitinase transcript abundance.

Two chitinase 5 genes from Locusta migratoria: Molecular characteristics and functional differentiation

“…Our results not only supported their findings but also extended the regulatory effect of 20E on duplicated LmCht5-2. Recently, miR-24 had been identified to regulate the expression of HaCht5 both in vitro and in vivo in H. armigera (Agrawal et al, 2013). Therefore, it is most likely that the expression of insect Cht5 is regulated by multiple factors.…”

Genome‐wide identification, expression profiling, and target gene analysis of microRNAs in the Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), vectors of tospoviruses (Bunyaviridae)

“…However, further experiments are required for the validation of these targets. Expression levels of T. tabaci miRNAs were validated by RT‐qPCR, and the results indicated few of these miRNAs have been predicted in the adult development process, which can be further utilized in gene functional studies through RNAi‐based approach or in developing miRNA mimics both for feeding and in planta expression (Agrawal, Sachdev, Rodrigues, Sowjanya Sree, & Bhatnagar, 2013; Jayachandran, Hussain, & Asgari, 2013; Nandety et al., 2015) as novel pest management strategies based on gene silencing and insect transgenesis.…”

ECDYSTEROID AND CHITINASE FLUCTUATIONS IN THE WESTERN TARNISHED PLANT BUG (Lygus hesperus) PRIOR TO MOLT INDICATE ROLES IN DEVELOPMENT

“…() identified two group I chitinases (LmCht5‐1 and LmCht5‐2) in Locusta migratoria ; LmCht5‐2 was strictly a 20E primary‐responsive gene whereas LhCht5‐1 exhibited both primary and secondary 20E responses. The 20E transcriptional response may be further regulated by the microRNA (miRNA) machinery as evidenced by the role reported for miRNA‐24 in regulating the H. armigera chitinase hachi (Agrawal et al., ). There are also likely interaction effects with circulating concentrations of JH, which has been shown in other species to downregulate (Fukamizo and Kramer, ; Koga et al., ; Kramer et al., ) or promote (Royer et al., ) chitinase gene expression.…”