S-nitrosylation of the transcription factor MYB30 facilitates nitric oxide-promoted seed germination in Arabidopsis

The transcription factor MYB30 promotes iron homeostasis by maintaining the stability of the FIT transcription factor

Iron (Fe) is a vital nutrient for the growth and development of plants. In Arabidopsis (Arabidopsis thaliana), the bHLH transcription factor FER-LIKE IRON-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) plays a pivotal role in regulating the response to Fe deficiency. Our study reveals that the R2R3-MYB transcription factor MYB30 is a positive regulator of the Fe-deficiency response by regulating FIT stability. Plants with loss-of-function mutations in MYB30 exhibit pronounced Fe-deficiency symptoms and diminished Fe uptake, while overexpression of MYB30 leads to the opposite effects. We have discovered that MYB30 interacts with BRUTUS LIKE1 (BTSL1) and BTSL2, 2 partially redundant E3 ubiquitin ligases that negatively regulate the Fe-deficiency response. MYB30 binds to the C-terminal region of BTSL1 through its MYB DNA-binding domain, thereby safeguarding FIT from BTSL1-mediated ubiquitination and degradation, resulting in FIT accumulation for Fe-deficiency response. In summary, our research uncovers the role of the transcription factor MYB30 as a regulator of FIT stability, which in turn modulates Fe homeostasis in plants in response to Fe deficiency.

The roles of protein S-nitrosylation in regulating the growth and development of plants: A review

The free radical nitric oxide (NO) is an important redox-related signaling molecule modulating wide range of biological processes in all living plants. The transfer of NO bioactivity could be executed chiefly through a prototypic, redox-based post-translational modification, S-nitrosylation that covalently adds NO moiety to a reactive cysteine thiol of a target protein to form an S-nitrosothiol. Protein S-nitrosylation is recently emerged as an evolutionarily conserved and important mechanism regulating multiple aspects of plant growth and development. Here, we review the recent progress of S-nitrosylated proteins in the modulation of various plant development processes, including seed germination and aging, root development, seedling growth, flowering and fruit ripening and postharvest fruit quality. More importantly, the detailed function mechanism of proteins S-nitrosylation and key challenges in this field are also highlighted.

Nitrate attenuates abscisic acid signaling via NIN-LIKE PROTEIN8 in Arabidopsis seed germination

Abscisic acid (ABA) suppresses Arabidopsis (Arabidopsis thaliana) seed germination and post-germinative growth. Nitrate stimulates seed germination, but whether it directly regulates ABA signaling and the associated underlying molecular mechanisms remain unknown. Here, we showed that nitrate alleviates the repressive effects of ABA on seed germination independently of the nitric oxide (NO) pathway. Moreover, nitrate attenuates ABA signaling activated by ABSCISIC ACID INSENSITIVE3 (ABI3) and ABI5, two critical transcriptional regulators of the ABA pathway. Mechanistic analyses demonstrated that ABI3 and ABI5 physically interact with the nitrate signaling-related core transcription factor NIN-LIKE PROTEIN 8 (NLP8). After ABA treatment, NLP8 suppresses ABA responses during seed germination without affecting ABA content. Notably, nitrate represses ABA signaling mainly through NLP8. Genetic analyses showed that NLP8 acts upstream of ABI3 and ABI5. Specifically, NLP8 inhibits the transcriptional functions of ABI3 and ABI5, as well as their ABA-induced accumulation. Additionally, NLP8 overexpression largely suppresses the ABA hypersensitivity of mutant plants exhibiting impaired NO biosynthesis or signaling. Collectively, our study reveals that nitrate counteracts the inhibitory effects of ABA signaling on seed germination and provides mechanistic insights into the NLP8-ABI3/ABI5 interactions and their antagonistic relationships in ABA signaling.

Protein S-nitrosylation: roles for nitric oxide signaling in the regulation of stress-dependent phytohormones

Nitric oxide (NO) is integral to modulating a wide array of physiological processes in plants, chiefly through its interactions with phytohormones. This review explores the complex dynamics between NO with four principal phytohormones: abscisic acid (ABA), salicylic acid (SA), auxin, and jasmonic acid (JA). The primary focus is on NO-mediated reversible redox-based modifications with a specific emphasis on S-nitrosylation. The impact of NO-induced S-nitrosylation is profound as it regulates crucial proteins involved in hormone signaling pathways, thereby influencing their synthesis, stability, and functional activity. The review elucidates how NO-mediated S-nitrosylation orchestrates the activities of ABA, SA, auxin, and JA under varying stress conditions and developmental stages. By modulating these phytohormones, NO effectively directs plant responses to a spectrum of biotic and abiotic stresses. This comprehensive review synthesizes current knowledge on highlights the essential role of NO in the regulation of hormonal networks and provides a comprehensive understanding of how S-nitrosylation facilitates plant adaptation and enhances stress resilience.

C2-domain abscisic acid-related proteins regulate the dynamics of a plasma membrane H+-ATPase in response to alkali stress

Arabidopsis (Arabidopsis thaliana) H+-ATPase1 (AHA1), a plasma membrane (PM)-localized H+-ATPase, plays a key role in plant alkali stress tolerance by pumping protons from the cytoplasm to the apoplast. However, its molecular dynamics are poorly understood. We report that many C2-domain ABA-related (CAR) protein family members interact with AHA1 in Arabidopsis. Single or double mutants of CAR1, CAR6, and CAR10 had no obvious phenotype of alkali stress tolerance, while their triple mutants showed significantly higher tolerance to this stress. The disruption of AHA1 largely compromised the increased alkali stress tolerance of the car1car6car10 mutant, revealing a key role of CARs in AHA1 regulation during the plant's response to a high alkali pH. Furthermore, variable-angle total internal reflection fluorescence microscopy was used to observe AHA1-mGFP5 in intact Arabidopsis seedlings, revealing the presence of heterogeneous diffusion coefficients and oligomerization states in the AHA1 spots. In the aha1 complementation lines, alkali stress curtailed the residence time of AHA1 at the PM and increased the diffusion coefficient and particle velocity of AHA1. In contrast, the absence of CAR proteins decreased the restriction of the dynamic behavior of AHA1. Our results suggest that CARs play a negative role in plant alkali stress tolerance by interacting with AHA1 and provide a perspective to investigate the regulatory mechanism of PM H+-ATPase activity at the single-particle level.

PlZAT10 binds to the ABA catabolism gene PlCYP707A2 promoter to mediate seed dormancy release in Paeonia lactiflora

KEY MESSAGE

PlZAT10-PlCYP707A2 module promotes Paeonia lactiflora seeds germination. The herbaceous peony (Paeonia lactiflora) seeds exhibit double dormancy in the epicotyl and hypocotyl, which significantly inhibits the process of cultivation and breeding of new varieties. Nevertheless, the molecular mechanism underlying seed dormancy release in P. lactiflora remains to be fully identified. In this current study, we analyzed differentially expressed genes based on transcriptome data and selected the abscisic acid catabolic gene PlCYP707A2 for further investigation. The conserved domain of the protein indicated that PlCYP707A2 possessed a cytochrome P450 monooxygenase domain. Subcellular localization indicated that PlCYP707A2 was localized on the cytoplasm and cell membrane. Overexpression of PlCYP707A2 in P. lactiflora seeds decreased ABA contents and promoted seeds germination. The silencing of PlCYP707A2 resulted in seed dormancy and an alteration in the content of ABA. Moreover, yeast one-hybrid, electrophoretic mobility shift and dual-luciferase reporter assay revealed that PlZAT10 bound to the promoter of PlCYP707A2. In conclusion, the results demonstrated the mechanism of the PlZAT10-PlCYP707A2 module in regulating the dormancy release of P. lactiflora seeds, enriching relevant theories on seed dormancy and having significant implications for the herbaceous peony industry developing.

Reactive Byproducts of Plant Redox Metabolism and Protein Functions

Living organisms exhibit an impressive ability to expand the basic information encoded in their genome, specifically regarding the structure and function of protein. Two basic strategies are employed to increase protein diversity and functionality: alternative mRNA splicing and post-translational protein modifications (PTMs). Enzymatic regulation is responsible for the majority of the chemical reactions occurring within living cells. However, plants redox metabolism perpetually generates reactive byproducts that spontaneously interact with and modify biomolecules, including proteins. Reactive carbonyls resulted from the oxidative metabolism of carbohydrates and lipids carbonylate proteins, leading to the latter inactivation and deposition in the form of glycation and lipoxidation end products. The protein nitrosylation caused by reactive nitrogen species plays a crucial role in plant morphogenesis and stress reactions. The redox state of protein thiol groups modified by reactive oxygen species is regulated through the interplay of thioredoxins and glutaredoxins, thereby influencing processes such as protein folding, enzyme activity, and calcium and hormone signaling. This review provides a summary of the PTMs caused by chemically active metabolites and explores their functional consequences in plant proteins.

Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

Role of protein S-nitrosylation in plant growth and development

In plants, nitric oxide (NO) has been widely accepted as a signaling molecule that plays a role in different processes. Among the most relevant pathways by which NO and its derivatives realize their biological functions, post-translational protein modifications are worth mentioning. Protein S-nitrosylation has been the most studied NO-dependent regulatory mechanism; it is emerging as an essential mechanism for transducing NO bioactivity in plants and animals. In recent years, the research of protein S-nitrosylation in plant growth and development has made significant progress, including processes such as seed germination, root development, photosynthetic regulation, flowering regulation, apoptosis, and plant senescence. In this review, we focus on the current state of knowledge on the role of S-nitrosylation in plant growth and development and provide a better understanding of its action mechanisms.

Protein S-nitrosylation under abiotic stress: Role and mechanism

Abiotic stress is one of the main threats affecting crop growth and production. Nitric oxide (NO), an important signaling molecule involved in wide range of plant growth and development as well as in response to abiotic stress. NO can exert its biological functions through protein S-nitrosylation, a redox-based posttranslational modification by covalently adding NO moiety to a reactive cysteine thiol of a target protein to form an S-nitrosothiol (SNO). Protein S-nitrosylation is an evolutionarily conserved mechanism regulating multiple aspects of cellular signaling in plant. Recently, emerging evidence have elucidated protein S-nitrosylation as a modulator of plant in responses to abiotic stress, including salt stress, extreme temperature stress, light stress, heavy metal and drought stress. In addition, significant mechanism has been made in functional characterization of protein S-nitrosylated candidates, such as changing protein conformation, and the subcellular localization of proteins, regulating protein activity and influencing protein interactions. In this study, we updated the data related to protein S-nitrosylation in plants in response to adversity and gained a deeper understanding of the functional changes of target proteins after protein S-nitrosylation.