In recent years, the epitranscriptomic landscape of eukaryotic cells has rapidly expanded beyond the well-studied N6-methyladenosine (m6A) modification, uncovering a diverse array of chemical modifications that fine-tune RNA function. Among these, non-m6A internal modifications of messenger RNA (mRNA) have emerged as critical regulators of gene expression, particularly within the realm of plant biology. A groundbreaking review by Teng and Shen published in Nature Plants in 2026 delves into the burgeoning field of non-m6A mRNA modifications, highlighting their intricate roles in plant development and environmental responses. As we unravel these lesser-known marks, a new chapter unfolds in our understanding of RNA biology and its profound impact on plant physiology.
The epitranscriptome, defined by dynamic chemical modifications on RNA molecules, constitutes a crucial layer of gene regulation that operates post-transcriptionally. While m6A has traditionally dominated this landscape due to its prevalence and regulatory significance, recent investigations have illuminated other modifications such as 5-methylcytosine (m5C), N4-acetylcytidine (ac4C), and pseudouridine (Ψ) as pivotal mediators of mRNA metabolism in plants. These chemical alterations serve as molecular switches that influence RNA fate, affecting how transcripts are spliced, translated, stabilized, or transported over long distances within the plant organism.
Delving into the realm of m5C, this methylation on cytosine residues was once regarded primarily as a DNA modification but has now gained recognition as an important mRNA modification in plants. The presence of m5C has been linked to the modulation of mRNA stability and translation efficiency, suggesting a nuanced control layer that adjusts protein synthesis rates in accordance with developmental cues or stress signals. The enzymatic machinery responsible for m5C installation, including plant homologs of cytosine methyltransferases, has started to be characterized, revealing convergent and divergent evolutionary pathways compared to animal systems.
Another exciting avenue is the acetylation of cytidine residues resulting in ac4C marks on mRNA. This modification appears to enhance the translational output of targeted transcripts, supporting the biosynthesis of proteins under conditions where rapid adaptation is essential. The detection of ac4C in plant mRNA has required leveraging highly sensitive sequencing technologies, underscoring a trend in epitranscriptomic studies where methodological advances fuel biological discovery. Teng and Shen emphasize the emerging understanding that ac4C plays an indispensable role in stress resilience by optimizing protein production during adverse environmental challenges such as drought or pathogen attack.
Pseudouridine, the isomerization of uridine into a more chemically stable form, represents a ubiquitous RNA modification known from transfer and ribosomal RNAs but now also recognized within plant mRNAs. The structural consequences of Ψ incorporation include altered base pairing and enhanced RNA stability, which can influence splicing decisions and translation fidelity. In plants, pseudouridylation appears to participate in fine-tuning responses to abiotic stresses, ensuring that the transcriptional and translational machinery can adapt flexibly to fluctuating environmental parameters.
An additional and compelling feature of non-m6A modifications is their involvement in the regulation of alternative splicing—an RNA processing event crucial for proteomic diversity. Modifications such as m5C and Ψ occur near splice sites or within regulatory motifs, modulating spliceosome recognition and exon inclusion. This modulation broadens the capacity of plants to generate multiple transcript isoforms from a single gene, thereby expanding the repertoire of proteins available for developmental processes and stress responses.
Beyond local mRNA metabolism, non-m6A modifications contribute markedly to the orchestration of long-distance RNA transport, a phenomenon partly underpinning systemic signaling in plants. For instance, select chemically modified mRNAs are preferentially mobilized through the phloem, enabling the plant to coordinate growth and defense strategies at the organismal level. This transport capability challenges the conventional view of mRNA as a strictly cell-autonomous molecule and opens new prospects for understanding how chemical marks guide intercellular communication.
The detection and mapping of these non-m6A modifications have presented significant technical hurdles that the scientific community is now overcoming with rapid innovation. High-throughput sequencing advances, including chemical conversion-based methods, crosslinking-immunoprecipitation, and direct RNA nanopore sequencing, have transformed our capacity to identify modification sites at nucleotide resolution. Coupled with bioinformatics pipelines specifically designed to decipher modification signatures, these tools are illuminating the epitranscriptomic complexity of plant mRNAs with unprecedented clarity.
Teng and Shen further elaborate on the challenges ahead for the field, highlighting the need for integrative approaches that combine biochemical, genetic, and computational strategies to dissect the functional consequences of each modification. Particularly, the causal relationship between specific non-m6A marks and phenotypic outcomes in plants under diverse environmental regimes demands rigorous in vivo validation. Advancements in CRISPR-based epitranscriptomic editing hold promise for enabling such functional studies by selectively toggling modification presence on target transcripts.
Crucially, understanding the crosstalk between various chemical marks on the same mRNA molecule—epitranscriptomic “code” interactions—represents a frontier in plant RNA biology. Multiple modifications could synergize or antagonize each other’s effects, dynamically shaping mRNA fate in response to developmental stages or external stimuli. Disentangling such complex regulatory layers will provide a holistic view of how plants harness chemical modifications to thrive in challenging environments.
Implications of these insights extend into agricultural biotechnology, where harnessing or manipulating non-m6A modifications could enable the development of crops with enhanced growth rates, improved stress tolerance, or fine-tuned metabolic pathways. Epitranscriptomic engineering may complement traditional genetic modification and breeding techniques, offering precise control over gene expression without altering the underlying DNA sequence.
The review by Teng and Shen thus positions non-m6A mRNA modifications not merely as biochemical curiosities but as central players in the epigenetic modulation of plant life. With mounting evidence of their influence on key molecular processes, these modifications are redefining paradigms in RNA biology and plant science. As researchers continue to probe this rich biochemical landscape, the future promises deeper mechanistic insights and novel applications that leverage the epitranscriptome’s regulatory potential.
In conclusion, the expanding repertoire of non-m6A modifications marks a transformative era in understanding plant mRNA regulation. From m5C’s role in mRNA stability, ac4C’s enhancement of translation, to pseudouridine’s impact on RNA structure and function, these chemical marks orchestrate a sophisticated symphony of RNA metabolism. This expanding knowledge not only enriches fundamental biology but also paves innovative paths for crop improvement and sustainable agriculture in the face of global climate challenges.
Subject of Research: Non-m6A mRNA modifications in plants and their regulatory roles.
Article Title: Emerging roles of non-m6A mRNA modifications in plants.
Article References: Teng, Z., Shen, L. Emerging roles of non-m6A mRNA modifications in plants. Nat. Plants (2026). https://doi.org/10.1038/s41477-026-02284-x
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