skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Overexpression of stress granule protein TZF1 enhances salt stress tolerance by targeting ACA11 mRNA for degradation in Arabidopsis
Tandem CCCH zinc finger (TZF) proteins play diverse roles in plant growth and stress response. Although as many as 11 TZF proteins have been identified inArabidopsis, little is known about the mechanism by which TZF proteins select and regulate the target mRNAs. Here, we report thatArabidopsisTZF1 is a bona-fide stress granule protein. Ectopic expression ofTZF1(TZF1 OE), but not an mRNA binding-defective mutant (TZF1H186YOE), enhances salt stress tolerance inArabidopsis. RNA-seq analyses of NaCl-treated plants revealed that the down-regulated genes inTZF1 OEplants are enriched for functions in salt and oxidative stress responses. Because many of these down-regulated mRNAs contain AU- and/or U-rich elements (AREs and/or UREs) in their 3’-UTRs, we hypothesized that TZF1—ARE/URE interaction might contribute to the observed gene expression changes. Results from RNA immunoprecipitation-quantitative PCR analysis, gel-shift, and mRNA half-life assays indicate that TZF1 binds and triggers degradation of theautoinhibited Ca2+-ATPase 11(ACA11) mRNA, which encodes a tonoplast-localized calcium pump that extrudes calcium and dampens signal transduction pathways necessary for salt stress tolerance. Furthermore, this salt stress-tolerance phenotype was recapitulated inaca11null mutants. Collectively, our findings demonstrate that TZF1 binds and initiates degradation of specific mRNAs to enhance salt stress tolerance.  more » « less
Award ID(s):
1906060
PAR ID:
10558257
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
Frontiers in Plant Science
Date Published:
Journal Name:
Frontiers in Plant Science
Volume:
15
ISSN:
1664-462X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. 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. 
    more » « less
  2. Plants employ distinct mechanisms to respond to environmental changes. Modification of mRNA byN 6-methyladenosine (m6A), known to affect the fate of mRNA, may be one such mechanism to reprogram mRNA processing and translatability upon stress. However, it is difficult to distinguish a direct role from a pleiotropic effect for this modification due to its prevalence in RNA. Through characterization of the transient knockdown-mutants of m6A writer components and mutants of specific m6A readers, we demonstrate the essential role that m6A plays in basal resistance and pattern-triggered immunity (PTI). A global m6A profiling of mock and PTI-inducedArabidopsisplants as well as formaldehyde fixation and cross-linking immunoprecipitation-sequencing of the m6A reader, EVOLUTIONARILY CONSERVED C-TERMINAL REGION2 (ECT2) showed that while dynamic changes in m6A modification and binding by ECT2 were detected upon PTI induction, most of the m6A sites and their association with ECT2 remained static. Interestingly, RNA degradation assay identified a dual role of m6A in stabilizing the overall transcriptome while facilitating rapid turnover of immune-induced mRNAs during PTI. Moreover, polysome profiling showed that m6A enhances immune-associated translation by binding to the ECT2/3/4 readers. We propose that m6A plays a positive role in plant immunity by destabilizing defense mRNAs while enhancing their translation efficiency to create a transient surge in the production of defense proteins. 
    more » « less
  3. Abstract After transcription, a messenger RNA (mRNA) is further post‐transcriptionally regulated by several features including RNA secondary structure and covalent RNA modifications (specifically N6‐methyladenosine, m6A). Both RNA secondary structure and m6A have been demonstrated to regulate mRNA stability and translation and have been independently linked to plant responses to soil salinity levels. However, the effect of m6A on regulating RNA secondary structure and the combinatorial interplay between these two RNA features during salt stress response has yet to be studied. Here, we globally identify RNA‐protein interactions and RNA secondary structure during systemic salt stress. This analysis reveals that RNA secondary structure changes significantly during salt stress, and that it is independent of global changes in RNA‐protein interactions. Conversely, we find that m6A is anti‐correlated with RNA secondary structure in a condition‐dependent manner, with salt‐specific m6A correlated with a decrease in mRNA secondary structure during salt stress. Taken together, we suggest that salt‐specific m6A deposition and the associated loss of RNA secondary structure results in increases in mRNA stability for transcripts encoding abiotic stress response proteins and ultimately increases in protein levels from these stabilized transcripts. In total, our comprehensive analyses reveal important post‐transcriptional regulatory mechanisms involved in plant long‐term salt stress response and adaptation. 
    more » « less
  4. Gene expression is typically quantified as RNA abundance, which is influenced by both synthesis (transcription) and decay. Cytoplasmic decay typically initiates by deadenylation, after which decay can occur through any of three cytoplasmic decay pathways. Recent advances reveal several mechanisms by which RNA decay is regulated to control RNA abundance. mRNA can be post-transcriptionally modified, either indirectly through secondary structure or through direct modifications to the transcript itself, sometimes resulting in subsequent changes in mRNA decay rates. mRNA abundances can also be modified by tapping into pathways normally used for RNA quality control. Regulated mRNA decay can also come about through post-translational modification of decapping complex subunits. Likewise, mRNAs can undergo changes in subcellular localization (for example, the deposition of specific mRNAs into processing bodies, or P-bodies, where stabilization and destabilization occur in a transcript- and context-dependent manner). Additionally, specialized functions of mRNA decay pathways were implicated in a genome-wide mRNA decay analysis in Arabidopsis. Advances made using plants are emphasized in this review, but relevant studies from other model systems that highlight RNA decay mechanisms that may also be conserved in plants are discussed. 
    more » « less
  5. Summary Pre‐mRNA splicing is an essential step for the regulation of gene expression. In order to specifically capture splicing variants in plants for genome‐wide association studies (GWAS), we developed a software tool to quantify and visualise Variations of Splicing in Population (VaSP).VaSP can quantify splicing variants from short‐read RNA‐seq datasets and discover genotype‐specific splicing (GSS) events, which can be used to prioritise causal pre‐mRNA splicing events in GWAS. We applied our method to an RNA‐seq dataset with 328 samples from 82 genotypes from a rice diversity panel exposed to optimal and saline growing conditions.In total, 764 significant GSS events were identified in salt stress conditions. GSS events were used as markers for a GWAS with the shoot Na+accumulation, which identified six GSS events in five genes significantly associated with the shoot Na+content. Two of these genes,OsNUC1andOsRAD23emerged as top candidate genes with splice variants that exhibited significant divergence between the variants for shoot growth under salt stress conditions.VaSP is a versatile tool for alternative splicing analysis in plants and a powerful tool for prioritising candidate causal pre‐mRNA splicing and corresponding genomic variations in GWAS. 
    more » « less