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SUMMARY Plants respond to low temperatures by altering the mRNA abundance of thousands of genes contributing to numerous physiological and metabolic processes that allow them to adapt. At the post‐transcriptional level, these cold stress‐responsive transcripts undergo alternative splicing, microRNA‐mediated regulation and alternative polyadenylation, amongst others. Recently, m6A, m5C and other mRNA modifications that can affect the regulation and stability of RNA were discovered, thus revealing another layer of post‐transcriptional regulation that plays an important role in modulating gene expression. The importance of m6A in plant growth and development has been appreciated, although its significance under stress conditions is still underexplored. To assess the role of m6A modifications during cold stress responses, methylated RNA immunoprecipitation sequencing was performed in Arabidopsis seedlings esposed to low temperature stress (4°C) for 24 h. This transcriptome‐wide m6A analysis revealed large‐scale shifts in this modification in response to low temperature stress. Because m6A is known to affect transcript stability/degradation and translation, we investigated these possibilities. Interestingly, we found that cold‐enriched m6A‐containing transcripts demonstrated the largest increases in transcript abundance coupled with increased ribosome occupancy under cold stress. The significance of the m6A epitranscriptome on plant cold tolerance was further assessed using themtamutant in which the major m6A methyltransferase gene was mutated. Compared to the wild‐type, along with the differences inCBFsandCORgene expression levels, themtamutant exhibited hypersensitivity to cold treatment as determined by primary root growth, biomass, and reactive oxygen species accumulation. Furthermore, and most importantly, both non‐acclimated and cold‐acclimatedmtamutant demonstrated hypersensitivity to freezing tolerance. Taken together, these findings suggest a critical role for the epitranscriptome in cold tolerance of Arabidopsis.
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mRNA ADENOSINE METHYLASE promotes drought tolerance through N6 ‐methyladenosine‐dependent and independent impacts on mRNA regulation in Arabidopsis
Summary Among many mRNA modifications, adenine methylation at the N6position (N6‐methyladenosine, m6A) is known to affect mRNA biology extensively. The influence of m6A has yet to be assessed under drought, one of the most impactful abiotic stresses.We show thatArabidopsis thaliana(L.) Heynh. (Arabidopsis) plants lacking mRNA ADENOSINE METHYLASE (MTA) are drought‐sensitive. Subsequently, we comprehensively assess the impacts of MTA‐dependent m6A changes during drought on mRNA abundance, stability, and translation in Arabidopsis.During drought, there is a global trend toward hypermethylation of many protein‐coding transcripts that does not occur inmta. We also observe complex regulation of m6A at a transcript‐specific level, possibly reflecting compensation by other m6A components. Importantly, a subset of transcripts that are hypermethylated in an MTA‐dependent manner exhibited reduced turnover and translation inmta, compared with wild‐type (WT) plants, during drought. Additionally, MTA impacts transcript stability and translation independently of m6A. We also correlate drought‐associated deposition of m6A with increased translation of modulators of drought response, such asRD29A,COR47,COR413,ALDH2B,ERD7, andABF4in WT, which is impaired inmta.m6A is dynamic during drought and, alongside MTA, promotes tolerance by regulating drought‐responsive changes in transcript turnover and translation.
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- PAR ID:
- 10552307
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 245
- Issue:
- 1
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 183-199
- Size(s):
- p. 183-199
- Sponsoring Org:
- National Science Foundation
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