Overexpression of an Osa-miR162a Derivative in Rice Confers Cross-Kingdom RNA Interference-Mediated Brown Planthopper Resistance without Perturbing Host Development.

Wenzhong Shen,Jie Chen,Shanni Cao,Jian-Feng Li,Jinhui Liu,Wenqing Zhang

doi:10.3390/ijms222312652

Abstract

Rice is a main food crop for more than half of the global population. The brown planthopper (BPH, Nilaparvata lugens) is one of the most destructive insect pests of rice. Currently, repeated overuse of chemical insecticides represents a common practice in agriculture for BPH control, which can induce insect tolerance and provoke environmental concerns. This situation calls for innovative and widely applicable strategies for rice protection against BPH. Here we report that the rice osa-miR162a can mediate cross-kingdom RNA interference (RNAi) by targeting the NlTOR (Target of rapamycin) gene of BPH that regulates the reproduction process. Through artificial diet or injection, osa-miR162a mimics repressed the NlTOR expression and impaired the oviposition of BPH adults. Consistently, overproduced osa-miR162a in transgenic rice plants compromised the fecundity of BPH adults fed with these plants, but meanwhile perturbed root and grain development. To circumvent this issue, we generated osa-miR162a-m1, a sequence-optimized osa-miR162a, by decreasing base complementarity to rice endogenous target genes while increasing base complementarity to NlTOR. Transgenic overexpression of osa-miR162a-m1 conferred rice resistance to BPH without detectable developmental penalty. This work reveals the first cross-kingdom RNAi mechanism in rice-BPH interactions and inspires a potentially useful approach for improving rice resistance to BPH. We also introduce an effective strategy to uncouple unwanted host developmental perturbation from desirable cross-kingdom RNAi benefits for overexpressed plant miRNAs.

Highlights

Rice (Oryza sativa) is one of the most important staple food crops worldwide
Sci. 2021, 22, 12652 sequence and function [28,35], we hypothesized that the NlTOR gene of BPH may be targeted by rice osa-miR162a, which has an identical sequence to bra-miR162a (Figure 1A)
As we have shown that injected osa-miR162a mimics could silence the NlTOR expression in BPH (Figure 1C) and compromise the oviposition of female insects (Figure 2D), we investigated whether the fecundity of BPH could be affected by continuous feeding on miR162a-OE or miR162a-m1-OE plants

Summary

Introduction

The application of excessive chemical insecticides remains a prevailing strategy for controlling this pest, at the expense of environmental damage and induced insecticide adaptation of the pests [2]. Another valuable and widely adoptable pest control strategy is the use of transgenic crops that produce the insecticidal Cry toxins from. Bt crops turned out to be ineffective for controlling piercing-sucking insects, such as BPH, which have developed a high-level resistance to a wide range of traditional pesticides [4,5]. Novel insecticidal transgene resources urgently need to be explored for rice protection against BPH

Methods

Results

Conclusion