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Journal of Integrative Agriculture  2026, Vol. 25 Issue (1): 192-206    DOI: 10.1016/j.jia.2025.02.009
Plant Protection Advanced Online Publication | Current Issue | Archive | Adv Search |
MicroRNA-mediated modulation of immune genes facilitates Metarhizium anisopliae infection in the red imported fire ant, Solenopsis invicta
Yating Xu*, Junaid Zafar*, Liangjie Lin, Hongxin Wu, Zehong Kang, Jie Zhang, Rana Fartab Shoukat, Yongyue Lu, Rui Pang, Fengliang Jin#, Xiaoxia Xu#

State Key Laboratory of Green Pesticide “Belt and Road” Technology Industry/Innovation Institute for Green and Biological Control of Agricultural Pests/College of Plant Protection, South China Agricultural University, Guangzhou 510642, China

 Highlights 
● Spatiotemporal profiling of host-encoded microRNAs revealed dynamic regulation of immune pathways in Metarhizium anisopliae-infected Solenopsis invicta.  
● MiR-71 and miR-7 regulated key immune pathway genes through direct targeting of ModSP1-Relish and Lysozyme2-Serine protease7, respectively.
● Manipulation of miR-71 and miR-7 impaired antifungal immunity and enhanced susceptibility to infection, offering insights for improved mycoinsecticide development.
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摘要  
红火蚁(Solenopsis invicta Buren)是一种高度侵入性的社会性害虫,威胁着当地的生物多样性、农业和人类健康。红火蚁的先天免疫系统以及复杂的社会免疫反应为制定有效的控制策略带来了挑战。MicroRNA (miRNA) 在基因表达的转录后调控中发挥着关键作用,影响多种生物过程,包括免疫和宿主-病原体相互作用。尽管miRNA 介导的昆虫对病原体的反应已在独居物种中得到广泛研究,但我们对社会昆虫群体中个体成员的先天免疫反应仍知之甚少。为了解决这一知识空白,我们从感染绿僵菌的红火工蚁中构建了小 RNA 文库,并研究了miRNA 介导的对昆虫病原体免疫反应的时间动态。我们鉴定了几种差异表达的miRNA,这些miRNA调控包括Toll、IMD和黑化免疫途径的基因。利用定量实时PCR (qRT-PCR)分析miRNA及其靶基因,特别关注miR-71/ModSP1-Relish和 miR-7/Lysozyme2-Serine protease7的时空动态。我们通过体外双荧光素酶测定验证了miRNA与其靶基因之间的相互作用。与对照组相比,miR-71和miR-7的过表达(通过添加miRNA模拟物)有效抑制了它们的靶基因。这一过程降低了红火蚁的抗真菌免疫反应,同时增加了对绿僵菌感染的易感性。此外,基于RNA干扰的基因沉默阐明了这些免疫基因在调节真菌敏感性中的作用。这为利用现代基因工程工具开发高效且具有毒性的杀真菌剂提供了重要的见解。




Abstract  

The red imported fire ant, Solenopsis invicta Buren, is a highly invasive eusocial insect pest that threatens native biodiversity, agriculture, and human health.  The innate immune system and intricate social immune responses of S. invicta pose challenges to the development of effective control strategies.  MicroRNAs (miRNAs) play critical roles in the post-transcriptional regulation of gene expression, which influences various biological processes, including immunity and host-pathogen interactions.  While the miRNA-mediated response of insects to pathogens has been extensively studied in solitary insects, little is known about the innate immune responses of individual members within a colony.  To address this gap, we constructed small RNA libraries from Metarhizium anisopliae-infected S. invicta workers and investigated the temporal dynamics of miRNA-mediated immune responses to the entomopathogen.  Several differentially expressed miRNAs were identified, and they were found to regulate genes involved in the Toll, IMD, and melanization immune pathways.  Quantitative real-time PCR (qRT-PCR) was employed to analyze the spatiotemporal dynamics of key miRNAs/target genes, specifically miR-71/ModSP1-Relish and miR-7/Lysozyme2-Serine protease7.  A dual luciferase assay (in vitro) was performed to validate the interactions between miRNAs and their target genes.  Overexpression of miR-71 and miR-7 (via miRNA mimics) efficiently suppressed their target genes, impaired the antifungal immune response of S. invicta and increased the susceptibility to M. anisopliae infection compared to controls.  Furthermore, RNA interference-based gene silencing elucidated the roles of these immune genes in regulating fungal susceptibility, thus providing vital clues for developing virulent and effective mycoinsecticides using modern genetic engineering tools.  

Keywords:  fire ants        microRNAs        RNAi        host-pathogen        innate immunity       entomopathogenic fungi  
Received: 28 October 2024   Accepted: 20 December 2024 Online: 10 February 2025  
Fund: 

This work was supported by grants from the National Natural Science Foundation of China (32172498 and W2433052), the National Key R&D Program of China (2021YFD1000500), and the Natural Science Foundation of Guangdong, China (2023A1515010305). 

About author:  Yating Xu, E-mail: xuyt1101@stu.scau.edu.cn; Junaid Zafar, E-mail: jz_jaam@yahoo.com; #Correspondence Fengliang Jin, E-mail: jflbang@scau.edu.cn; Xiaoxia Xu, E-mail: xuxiaoxia111@scau.edu.cn * These authors contributed equally to this study.

Cite this article: 

Yating Xu, Junaid Zafar, Liangjie Lin, Hongxin Wu, Zehong Kang, Jie Zhang, Rana Fartab Shoukat, Yongyue Lu, Rui Pang, Fengliang Jin, Xiaoxia Xu. 2026. MicroRNA-mediated modulation of immune genes facilitates Metarhizium anisopliae infection in the red imported fire ant, Solenopsis invicta. Journal of Integrative Agriculture, 25(1): 192-206.

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