Open AccessImprovement of host‐induced gene silencing efficiency via polycistronic‐tRNA‐amiR expression for multiple target genes and characterization of RNAi mechanism in Mythimna separata
Author(s) -
Bao Wenhua,
Li Aoga,
Zhang Yanan,
Diao Pengfei,
Zhao Qiqi,
Yan Ting,
Zhou Zikai,
Duan Huimin,
Li Xugang,
Wuriyanghan Hada
Publication year - 2021
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.13555
Subject(s) - rna interference , biology , mythimna separata , gene knockdown , gene silencing , rna silencing , gene , small interfering rna , gene expression , genetics , transgene , microbiology and biotechnology , rna , lepidoptera genitalia , botany
Summary Host‐induced gene silencing (HIGS) emerged as a new strategy for pest control. However, RNAi efficiency is reported to be low in Lepidoptera, which are composed of many important crop pests. To address this, we generated transgenic plants to develop HIGS effects in a maize pest, Mythimna separata (Lepidoptera, Noctuidae), by targeting chitinase encoding genes. More importantly, we developed an artificial microRNA (amiR) based PTA (polycistronic‐tRNA‐amiR) system for silencing multiple target genes. Compared with hpRNA (hairpin RNA), transgenic expression of a PTA cassette including an amiR for the gut‐specific dsRNA nuclease gene MsREase , resulted in improved knockdown efficiency and caused more pronounced developmental abnormalities in recipient insects. When target gene siRNAs were analysed after HIGS and direct dsRNA/siRNA feeding, common features such as sense polarity and siRNA hotspot regions were observed, however, they differed in siRNA transitivity and major 20‐24nt siRNA species. Core RNAi genes were identified in M. separata , and biochemical activities of MsAGO2, MsSID1 and MsDcr2 were confirmed by EMSA (electrophoretic mobility shift assay) and dsRNA cleavage assays, respectively. Taken together, we provide compelling evidence for the existence of the RNAi mechanism in M. separata by analysis of both siRNA signatures and RNAi machinery components, and the PTA system could potentially be useful for future RNAi control of lepidopteran pests.