N6-methyladenosine modification of the mRNA for a key gene in purine nucleotide metabolism regulates virus proliferation in an insect vector

MeRIP-Seq initially revealed the role of m6A modification in Chinese sacbrood virus-infected Apis cerana larvae

Chinese sacbrood virus (CSBV) is highly lethal to honeybee larvae (especially the larva of Apis cerana) and causes considerable losses to beekeeping industry. N6-methyladenine (m6A) modification of mRNA is a predominant post-transcriptional modification in eukaryotes and plays a role in viral infection. However, the role of m6A modification in CSBV infection remains unclear. Herein, we performed high-throughput sequencing for m6A-seq in CSBV-infected and non-infected larvae to investigate host transcriptome-wide m6A modifications and identify m6A-modified genes. A total of 671 variant peaks were identified. Combined analysis of m6A modification and mRNA expression revealed that a significant correlation between mRNA methylation modifications and expression levels observed for 668 Genes. It was proved that CSBV infection can cause important m6A modification changes in host. We examined the effects of CSBV infection on expression of two methylation regulatory genes by qPCR. At the same time, we verified the effect of two methylation regulatory genes on CSBV replication using RNAi technology. This study demonstrated for the first time that CSBV infection can cause m6A modification changes in A. cerana larvae, and comprehensively analyzed the m6A modification pattern of its mRNA, and CSBV infection significantly promoted the expression of AcMETTL3 (Ac represents A. cerana, p = 0.007), but had no effect on the expression of AcMETTL14. It was further confirmed that AcMETTL3 had a significant negative regulatory effect on CSBV replication (p = 0.0432). These results lay a foundation for further exploration of the role of m6A modification in CSBV infection.

Exploring the Role of mRNA Methylation in Insect Biology and Resistance

RNA methylation, characterized by modifications such as N6-methyladenosine, 5-methylcytosine, and N1-methyladenosine plays a crucial role in post-transcriptional gene regulation across diverse biological systems. While research on RNA methylation has predominantly focused on mammals, particularly its roles in epigenetic regulation and cancer biology, recent studies in insects have begun to explore their extensive functions in insect physiology. This review examines the mechanisms by which RNA methylation regulates growth, development, reproduction, environmental adaptation, and immune response in insects, providing insights into the biological characteristics of these organisms without prematurely speculating on pest control strategies. It aims to offer valuable insights into the role of RNA methylation in insect biology and resistance.

RNA modifications in plant biotic interactions

The chemical modifications of DNA and proteins are powerful mechanisms for regulating molecular and biological functions, influencing a wide array of signaling pathways in eukaryotes. Recent advancements in epitranscriptomics have shown that RNA modifications play crucial roles in diverse biological processes. Since their discovery in the 1970s, scientists have sought to decipher, identify, and elucidate the functions of these modifications across biological systems. Over the past decade, mounting evidence has demonstrated the importance of RNA modification pathways in plants, prompting significant efforts to decipher their physiological relevance. With the advent of high-resolution mapping techniques for RNA modifications and the gradual uncovering of their biological roles, our understanding of this additional layer of regulation is beginning to take shape. In this review, we summarize recent findings on the major RNA modifications identified in plants, with an emphasis on N6-methyladenosine (m6A), the most extensively studied modification. We discuss the functional significance of the effector components involved in m6A modification and its diverse roles in plant biotic interactions, including plant-virus, plant-bacterium, plant-fungus, and plant-insect relationships. Furthermore, we highlight new technological developments driving research progress in this field and outline key challenges that remain to be addressed.

N6-methyladenosine (m6A) modification: Emerging regulators in plant-virus interactions

N6-methyladenosine (m6A), a reversible epigenetic modification, is widely present on both cellular and viral RNAs. This modification undergoes catalysis by methyltransferases (writers), removal by demethylases (erasers), and recognition by m6A-binding proteins (readers), ultimately influencing the fate and function of modified RNA molecules. With recent advances in sequencing technologies, the genome-wide mapping of m6A has become possible, enabling a deeper exploration of its roles during viral infections. So far, while the significance of m6A in regulating virus-host interactions has been well-established in animal viruses, research on its involvement in plant viruses remains in its early stages. In this review, we summarize the current knowledge regarding the functions and molecular mechanisms of m6A in plant-virus interactions. A better understanding of these complex interactions may provide valuable insights for developing novel antiviral strategies, potentially leading to more effective control of plant viral diseases in the field.

Dual Guardians of Immunity: FoRab10 and FoRab29 in Frankliniella occidentalis Confer Resistance to Tomato Spotted Wilt Orthotospovirus

Rab GTPase is critical for autophagy processes and is implicated in insect immunity against viruses. In this study, we aimed to investigate the role of FoRabs in the autophagic regulation of antiviral defense against tomato spotted wilt orthotospovirus (TSWV) in Frankliniella occidentalis. Transcriptome analysis revealed the downregulation of FoRabs in viruliferous nymph and adults of F. occidentalis in response to TSWV infection. Manipulation of autophagy levels with 3-MA and Rapa treatments resulted in a 5- to 15-fold increase and a 38-64% decrease in viral titers, respectively. Additionally, interference with FoRab10 in nymphs and FoRab29 in adults led to a 20-90% downregulation of autophagy-related genes, a decrease in ATG8-II (an autophagy marker protein), and an increase in the TSWV titers by 1.5- to 2.5-fold and 1.3- to 2.0-fold, respectively. In addition, the leaf disk and the living plant methods revealed increased transmission rates of 20.8-41.6 and 68.3-88.3%, respectively. In conclusion, FoRab10 and FoRab29 play a role in the autophagic regulation of the antiviral defense in F. occidentalis nymphs and adults against TSWV, respectively. These findings offer insights into the intricate immune mechanisms functional in F. occidentalis against TSWV, suggesting potential targeted strategies for F. occidentalis and TSWV management.

N6-methyladenosine modification of RNA controls dopamine synthesis to influence labour division in ants

The N6-methyladenosine (m6A) modification of RNA has been reported to remodel gene expression in response to environmental conditions; however, the biological role of m6A in social insects remains largely unknown. In this study, we explored the role of m6A in the division of labour by worker ants (Solenopsis invicta). We first determined the presence of m6A in RNAs from the brains of worker ants and found that m6A methylation dynamics differed between foragers and nurses. Depletion of m6A methyltransferase or chemical suppression of m6A methylation in foragers resulted in a shift to 'nurse-like' behaviours. Specifically, mRNAs of dopamine receptor 1 (Dop1) and dopamine transporter (DAT) were modified by m6A, and their expression increased dopamine levels to promote the behavioural transition from foragers to nurses. The abundance of Dop1 and DAT mRNAs and their stability were reduced by the inhibition of m6A modification caused by the silencing of Mettl3, suggesting that m6A modification in worker ants modulates dopamine synthesis, which regulates labour division. Collectively, our results provide the first example of the epitranscriptomic regulation of labour division in social insects and implicate m6A regulatory mechanism as a potential novel target for controlling red imported fire ants.