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ABSTRACT Modifications to RNA have recently been recognized as a pivotal regulator of gene expression in living organisms. More than 170 chemical modifications have been identified in RNAs, with N6‐methyladenosine (m6A) being the most abundant modification in eukaryotic mRNAs. The addition and removal of m6A marks are catalyzed by methyltransferases (referred to as “writers”) and demethylases (referred to as “erasers”), respectively. In addition, the m6A marks in mRNAs are recognized and interpreted by m6A‐binding proteins (referred to as “readers”), which regulate the fate of mRNAs, including stability, splicing, transport, and translation. Therefore, exploring the mechanism underlying the m6A reader‐mediated modulation of RNA metabolism is essential for a much deeper understanding of the epigenetic role of RNA modification in plants. Recent discoveries have improved our understanding of the functions of m6A readers in plant growth and development, stress response, and disease resistance. This review highlights the latest developments in m6A reader research, emphasizing the diverse RNA‐binding domains crucial for m6A reader function and the biological and cellular roles of m6A readers in the plant response to developmental and environmental signals. Moreover, we propose and discuss the potential future research directions and challenges in identifying novel m6A readers and elucidating the cellular and mechanistic role of m6A readers in plants. [ABSTRACT FROM AUTHOR]

Climate change has emerged as a crucial global issue that significantly threatens the survival of plants. In particular, low temperature (LT) is one of the critical environmental factors that influence plant morphological, physiological, and biochemical changes during both the vegetative and reproductive growth stages. LT, including abrupt drops in temperature, as well as winter conditions, can cause detrimental effects on the growth and development of tomato plants, ranging from sowing, transplanting, truss appearance, flowering, fertilization, flowering, fruit ripening, and yields. Therefore, it is imperative to understand the comprehensive mechanisms underlying the adaptation and acclimation of tomato plants to LT, from the morphological changes to the molecular levels. In this review, we discuss the previous and current knowledge of morphological, physiological, and biochemical changes, which contain vegetative and reproductive parameters involving the leaf length (LL), plant height (PH) stem diameter (SD), fruit set (FS), fruit ripening (FS), and fruit yield (FY), as well as photosynthetic parameters, cell membrane stability, osmolytes, and ROS homeostasis via antioxidants scavenging systems during LT stress in tomato plants. Moreover, we highlight recent advances in the understanding of molecular mechanisms, including LT perception, signaling transduction, gene regulation, and fruit ripening and epigenetic regulation. The comprehensive understanding of LT response provides a solid basis to develop the LT-resistant varieties for sustainable tomato production under the ever-changing temperature fluctuations. [ABSTRACT FROM AUTHOR]

N6‐methyladenosine (m6A) is an mRNA modification widely found in eukaryotes and plays a crucial role in plant development and stress responses. FIONA1 (FIO1) is a recently identified m6A methyltransferase that regulates Arabidopsis (Arabidopsis thaliana) floral transition; however, its role in stress response remains unknown. In this study, we demonstrate that FIO1‐mediated m6A methylation plays a vital role in salt stress response in Arabidopsis. The loss‐of‐function fio1 mutant was sensitive to salt stress. Importantly, the complementation lines expressing the wild‐type FIO1 exhibited the wild‐type phenotype, whereas the complementation lines expressing the mutant FIO1m, in which two critical amino acid residues essential for methyltransferase activity were mutated, did not recover the wild‐type phenotype under salt stress, indicating that the salt sensitivity is associated with FIO1 methyltransferase activity. Furthermore, FIO1‐mediated m6A methylation regulated ROS production and affected the transcript level of several salt stress‐responsive genes via modulating their mRNA stability in an m6A‐dependent manner in response to salt stress. Importantly, FIO1 is associated with salt stress response by specifically targeting and differentially modulating several salt stress‐responsive genes compared with other m6A writer. Collectively, our findings highlight the molecular mechanism of FIO1‐mediated m6A methylation in the salt stress adaptation. Summary Statement: FIONA1 (FIO1), a recently identified m6A methyltransferase, plays a vital role in salt stress response by modulating the stability of several m6A‐modified salt stress‐responsive genes in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]

Although several studies have shown that AlkB homolog (ALKBH) proteins are potential RNA demethylases (referred to as 'erasers'), biological functions of only a few ALKBH proteins have been characterized to date. In this study, we determined the function of ALKBH9C (At4g36090) in seed germination and seedling growth of Arabidopsis thaliana in response to abiotic stress and abscisic acid (ABA). Seed germination of the alkbh9c mutant was delayed in response to salt, drought, cold and ABA. Moreover, seedling growth of the mutant was repressed under salt stress or ABA but enhanced under drought conditions. Notably, the stress‐responsive phenotypes were associated with the altered expression of several m6A‐modified transcripts related to salt, drought or ABA response. Global m6A levels were increased in the alkbh9c mutant, and ALKBH9C bound to m6A‐modified RNAs and had in vitro m6A demethylase activity, suggesting its potential role as an m6A eraser. The m6A levels in several stress‐responsive genes were increased in the alkbh9c mutant, and the stability of m6A‐modified transcripts was altered in the mutant. Collectively, our results suggest that m6A eraser ALKBH9C is crucial for seed germination and seedling growth of Arabidopsis in response to abiotic stresses or ABA via affecting the stability of stress‐responsive transcripts. Summary statement: Addition and removal of methylation marks in RNAs is critical for the response of plants to abiotic stresses and abscisic acid. In this study, we show that ALKBH9C is a potential m6A demethylase that plays a crucial role in seed germination and seedling growth of Arabidopsis in response to salt stress, drought stress, and abscisic acid. [ABSTRACT FROM AUTHOR]