RESUMO
The rice zinc finger protein ZFP36 serves as a pivotal regulator of the hydrogen peroxide (H2O2) signaling pathway in response to abscisic acid (ABA). Its role is crucial for integrating H2O2 signals with the plant defense mechanisms against water deficit and oxidative stress. However, it remains unclear whether ZFP36 directly modulates ABA-induced H2O2 signaling. This study explored the effects of oxidative post-translational modifications (OxiPTMs) on ZFP36 in rice, with an emphasis on the H2O2-induced oxidation through its cysteine (Cys) residues. We found that ZFP36 undergoes oxidative modification as a target of H2O2 in the presence of ABA, specifically at Cys32. Employing quantitative detection and fluorescence assays, we observed that ZFP36 oxidation enhances the expression and activity of genes encoding protective antioxidant enzymes. Moreover, our investigation into the thioredoxin (Trx) and glutaredoxin (Grx) families revealed that OsTrxh1 facilitates the reduction of oxidized ZFP36. Genetic evidence indicates that ZFP36 positively influences rice resilience to oxidative and water stress, while OsTrxh1 exerts an opposing effect. These insights reveal a distinctive pathway for plant cells to perceive ABA-induced H2O2 signaling, advance our comprehension of H2O2 signaling dynamics, and ABA-related plant responses, and lay a vital groundwork for enhancing crop stress tolerance.
Assuntos
Ácido Abscísico , Peróxido de Hidrogênio , Oryza , Oxirredução , Proteínas de Plantas , Transdução de Sinais , Oryza/metabolismo , Oryza/genética , Oryza/efeitos dos fármacos , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Peróxido de Hidrogênio/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Transdução de Sinais/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Dedos de Zinco , Processamento de Proteína Pós-TraducionalRESUMO
Rainstorm flooding in developed urban areas has become a global focus. This study proposes a data-driven approach to urban rainstorm flood risk assessment. In contrast to the existing research, this study focuses on terrain watersheds as an assessment unit. Using Changsha as the study area, an inventory of 238 historical rainstorm flood locations was produced using automatic web crawling and literature data mining. Subsequently, an assessment model was developed based on a Bayesian algorithm and 16 influencing factors, and its accuracy was verified using a receiver operating characteristic curve. Because underground infrastructure is prone to backflow at its entrances and exits during rainstorms, the developed model was used to assess the backflow risk of two typical underground structures subjected to three rainstorm return periods: 5 (scenario 1), 10 (scenario 2), and 100 years (scenario 3). The conclusions are as follows: (1) The proposed method has a prediction accuracy of 88 % for flood risk. The most influential factors were H11 (proportion of impervious surface), H4 (mean elevation), and H1 (rainfall), contributing 52 %, 14.3 %, and 11.9 %, respectively. (2) Watersheds are classified into "Very Low," "Low," "High," and "Very High" based on the degree of flooding impact, accounting for 83.6 %, 11.9 %, 3.9 %, and 0.7 %, respectively. Watersheds classified as "Very High" are mainly distributed in the central region. (3) A total of 48 subway stations (7.9 % of the total) and 148 underground parking lots (6.5 % of the total) in the study area are located in "Very High" risk areas. (4) Compared to that in scenario 1, the proportion of underground entrances and exits with a "Very high" protection level in scenario 3 increased by approximately 10 %. In conclusion, this framework can assist urban planners in understanding the risks of urban flooding and mitigating potential flooding impacts.
RESUMO
We introduce a biotinylated D-amino acid probe capable of metabolically incorporating into bacterial PG. Leveraging the robust affinity between biotin and streptavidin, the probe has demonstrated efficacy in imaging, capture, and targeted inactivation of Gram-positive bacteria through synergistic pairings with commercially available streptavidin-modified fluorescent dyes and nanomaterials. The versatility of the probe is underscored by its compatibility with a variety of commercially available streptavidin-modified reagents. This adaptability allows the probe to be applied across diverse scenarios by integrating with these commercial reagents.
Assuntos
Bactérias , Biotina , Estreptavidina/química , Biotina/química , Bactérias/metabolismo , Corantes Fluorescentes/química , Bactérias Gram-Positivas/metabolismoRESUMO
Salinity is a significant abiotic stress factor affecting plant growth, consequently reducing crop yield. Abscisic acid (ABA), a well-known phytohormone, is crucial in conferring resistance to abiotic stress, thus, understanding the mechanisms underlying ABA biosynthesis is crucial. In rice (Oryza sativa L.), OsABA2, a short-chain dehydrogenase protein, has a pivotal role in modulating ABA biosynthesis and salt tolerance by undergoing phosphorylation at Ser197 through mitogen-activated protein kinase OsMPK1. However, the interaction between OsABA2 and other proteins in regulating ABA biosynthesis remains unclear. We employed OsABA2 as a bait in yeast two-hybrid screening: a basic helix-loop-helix transcription factor interacting with OsABA2, named OsbHLH110, was identified. Our results showed that firefly luciferase complementary imaging, pull-down, and co-immunoprecipitation assays validated the interaction between OsbHLH110 and OsABA2, affirming their interaction in vivo and in vitro. Moreover, the expression of OsbHLH110 significantly increases in response to salt and ABA treatments. Additionally, OsbHLH110 can directly bind to the G-box element in the OsABA2 promoter. This binding enhances luciferase activity controlled by the OsABA2 promoter, thereby increasing the expression of the OsABA2 gene and content of the OsABA2 protein, resulting in an increase in ABA content. OsABA2 enhanced the interaction between OsbHLH110 and OsABA2 promoter. This collaborative effect enhanced the regulation of ABA biosynthesis. Subsequent genetic analysis demonstrated that OsbHLH110 improved the tolerance of rice to salt stress.
Assuntos
Ácido Abscísico , Oryza , Ácido Abscísico/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Tolerância ao Sal , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/metabolismo , SalinidadeRESUMO
Peptidoglycan, an essential component within the cell walls of virtually all bacteria, is composed of glycan strands linked by stem peptides that contain D-amino acids. The peptidoglycan biosynthesis machinery exhibits high tolerance to various D-amino acid derivatives. D-amino acid derivatives with different functionalities can thus be specifically incorporated into and label the peptidoglycan of bacteria, but not the host mammalian cells. This metabolic labeling strategy is highly selective, highly biocompatible, and broadly applicable, which has been utilized in various fields. This review introduces the metabolic labeling strategies of peptidoglycan by using D-amino acid derivatives, including one-step and two-step strategies. In addition, we emphasize the various applications of D-amino acid derivative-based metabolic labeling, including bacterial peptidoglycan visualization (existence, biosynthesis, and dynamics, etc.), bacterial visualization (including bacterial imaging and visualization of growth and division, metabolic activity, antibiotic susceptibility, etc.), pathogenic bacteria-targeted diagnostics and treatment (positron emission tomography (PET) imaging, photodynamic therapy, photothermal therapy, gas therapy, immunotherapy, etc.), and live bacteria-based therapy. Finally, a summary of this metabolic labeling and an outlook is provided.
Assuntos
Bactérias , Peptidoglicano , Peptidoglicano/metabolismo , Bactérias/metabolismo , Aminoácidos/química , Parede Celular/metabolismoRESUMO
Rice OsBBX17 encodes a B-box zinc finger transcription factor in which the N-terminal B-box structural domain interacts with OsMPK1. In addition, it directly binds to the G-box of OsHAK2 and OsHAK7 promoters and represses their transcription. Under saline-alkaline conditions, the expression of OsBBX17 was inhibited. Meanwhile, activation of the OsMPK1-mediated mitogen-activated protein kinase cascade pathway caused OsMPK1 to interact with OsBBX17 and phosphorylate OsBBX17 at the Thr-95 site. It reduced OsBBX17 DNA-binding activity and enhanced saline-alkaline tolerance by deregulating transcriptional repression of OsHAK2 and OsHAK7. Genetic assays showed that the osbbx17-KO had an excellent saline-alkaline tolerance, whereas the opposite was in OsBBX17-OE. In addition, overexpression of OsMPK1 significantly improved saline-alkaline tolerance, but knockout of OsMPK1 caused an increased sensitivity. Further overexpression of OsBBX17 in the osmpk1-KO caused extreme saline-alkaline sensitivity, even a quick death. OsBBX17 was validated in saline-alkaline tolerance from two independent aspects, transcriptional level and post-translational protein modification, unveiling a mechanistic framework by which OsMPK1-mediated phosphorylation of OsBBX17 regulates the transcription of OsHAK2 and OsHAK7 to enhance the Na+ /K+ homeostasis, which partially explains light on the molecular mechanisms of rice responds to saline-alkaline stress via B-box transcription factors for the genetic engineering of saline-alkaline tolerant crops.
Assuntos
Oryza , Fatores de Transcrição , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Oryza/metabolismo , Fosforilação , Tolerância ao Sal/genética , Sistema de Sinalização das MAP Quinases , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
Vegetative phase change in plants is regulated by a gradual decline in the level of miR156 and a corresponding increase in the expression of its targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes. Gibberellin (GA), jasmonic acid (JA), and cytokinin (CK) regulate vegetative phase change by affecting genes in the miR156-SPL pathway. However, whether other phytohormones play a role in vegetative phase change remains unknown. Here, we show that a loss-of-function mutation in the brassinosteroid (BR) biosynthetic gene, DWARF5 (DWF5), delays vegetative phase change, and the defective phenotype is primarily attributable to reduced levels of SPL9 and miR172, and a corresponding increase in TARGET OF EAT1 (TOE1). We further show that GLYCOGEN SYNTHASE KINASE3 (GSK3)-like kinase BRASSINOSTEROID INSENSITIVE2 (BIN2) directly interacts with and phosphorylates SPL9 and TOE1 to cause subsequent proteolytic degradation. Therefore, BRs function to stabilize SPL9 and TOE1 simultaneously to regulate vegetative phase change in plants.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , MicroRNAs , Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Proteínas Quinases/genética , Proteínas Quinases/metabolismoRESUMO
In rice, the Ca2+/calmodulin-dependent protein kinase OsDMI3 is an important positive regulator of abscisic acid (ABA) signaling. In ABA signaling, H2O2 is required for ABA-induced activation of OsDMI3, which in turn increase H2O2 production. However, how OsDMI3 regulates H2O2 production in ABA signaling remains unknown. Here we show that OsRbohB is the main NADPH oxidase involved in ABA-induced H2O2 production and ABA-mediated physiological responses. OsDMI3 directly interacts with and phosphorylates OsRbohB at Ser-191, which is OsDMI3-mediated site-specific phosphorylation in ABA signaling. Further analyses revealed that OsDMI3-mediated OsRbohB Ser-191 phosphorylation positively regulates the activity of NADPH oxidase and the production of H2O2 in ABA signaling, thereby enhancing the sensitivity of seed germination and root growth to ABA and plant tolerance to water stress and oxidative stress. Moreover, we discovered that the OsDMI3-mediated OsRbohB phosphorylation and H2O2 production is dependent on the sucrose non-fermenting 1-related protein kinases SAPK8/9/10, which phosphorylate OsRbohB at Ser-140 in ABA signaling. Taken together, these results not only reveal an important regulatory mechanism that directly activates Rboh for ABA-induced H2O2 production but also uncover the importance of this regulatory mechanism in ABA signaling.
Assuntos
Oryza , Proteínas Quinases , Proteínas Quinases/metabolismo , Fosforilação , Peróxido de Hidrogênio/metabolismo , Oryza/metabolismo , Ácido Abscísico/metabolismo , NADPH Oxidases/metabolismoRESUMO
Overly Na+ ion in soil caused by salt stress has a significant negative impact on the growth and production of crops, especially rice (Oryza sativa L.). Therefore, it is vital for us to clarify how salt stress tolerance in rice is caused by Na+ ion toxicity. The UDP-glucuronic acid decarboxylase (UXS) is a critical enzyme in the biosynthesis of UDP-xylose, which is the key substrate of cytoderm synthesis in plants. In this study, we found that OsUXS3, a rice UXS, is a positive regulator to regulate Na+ ion toxicity under salt stress by interacting with OsCATs (Oryza sativa catalase; OsCAT). The expression of OsUXS3 was significantly up-regulated under NaCl and NaHCO3 treatments of rice seedlings. Meanwhile, by the genetic and biochemical evidence, knockout of OsUXS3 significantly increased reactive oxygen species (ROS) levels and decreased CAT activity under NaCl and NaHCO3 treatments in tissue. Furthermore, knockout of OsUXS3 caused excessive accumulation of Na + ion and rapid loss of K+ ion and disrupts Na+/K+ homeostasis under NaCl and NaHCO3 treatments. Based on the results above, we can conclude that OsUXS3 might regulate CAT activity by interacting with OsCATs, which is not only characterized for the first time but also regulating Na+/K+ homeostasis, positively regulating the Na+ ion toxicity tolerance under salt stress in rice.
Assuntos
Oryza , Oryza/metabolismo , Cloreto de Sódio/farmacologia , Cloreto de Sódio/metabolismo , Estresse Salino , Sódio/metabolismoRESUMO
In this work, we illustrate a strategy for constructing heterochiral peptide architectures with distinct structural, mechanical and thermal characteristics. A series of nanotube structures based on diphenylalanine (FF) and its chiral derivatives were examined. Pronounced effects relating to heterochirality on mechanostability and thermal stability can be identified. The homochiral peptide FF and its enantiomer ff formed nanotubes with high thermal and mechanical stabilities (Young's modulus: 20.3 ± 5.9 GPa for FF and 21.2 ± 4.7 GPa for ff). In contrast, heterochiral nanotubes formed by Ff and fF manifest superstructures along the axial direction with differed thermal and mechanical strength (Young's modulus: 7.3 ± 2.4 GPa for Ff and 8.3 ± 2.1 GPa for fF). Combining their single-crystal XRD structure and in silico results, it was demonstrated that the spatial orientations of aromatic moieties were subtly changed by heterochirality of peptide building blocks, which led to intramolecular face-to-face interactions. As the result, both intermolecular axial and interchannel interactions in heterochiral nanotubes were weakened as reflected in the strikingly deteriorated mechanical and thermal stabilities. Conversely, two aromatic side chains of the homochiral peptides were staggered and formed interdigitated steric zippers, which served as strong glues that secured the robustness of nanotubes in both axial and radial orientation. Furthermore, the generality of the heterochiral-mediated stereochemical effects was demonstrated in other "FF class" dipeptides, including fluorinated Ff, FW and FL. Our results unequivocally revealed the relationship between amino acid chirality, peptide molecule packing, and physical stabilities of "FF class" dipeptide self-assembled materials and provide valuable molecular insights into chirality-mediated stereochemical interactions in determining the properties of peptide architectures.
Assuntos
Nanotubos , Peptídeos , Peptídeos/química , Dipeptídeos/química , Fenilalanina/química , Aminoácidos/química , Nanotubos/química , EstereoisomerismoRESUMO
Calcium (Ca2+ )/calmodulin (CaM)-dependent protein kinase (CCaMK) is an important positive regulator of antioxidant defenses and tolerance against oxidative stress. However, the underlying molecular mechanisms are largely unknown. Here, we report that the rice (Oryza sativa) CCaMK (OsDMI3) physically interacts with and phosphorylates OsUXS3, a cytosol-localized UDP-xylose synthase. Genetic and biochemical evidence demonstrated that OsUXS3 acts downstream of OsDMI3 to enhance the oxidative stress tolerance conferred by higher catalase (CAT) activity. Indeed, OsUXS3 interacted with CAT isozyme B (OsCATB), and this interaction was required to increase OsCATB protein abundance under oxidative stress conditions. Furthermore, we showed that OsDMI3 phosphorylates OsUXS3 on residue Ser-245, thereby further promoting the interaction between OsUXS3 and OsCATB. Our results indicate that OsDMI3 promotes the association of OsUXS3 with OsCATB to enhance CAT activity under oxidative stress. These findings reveal OsUXS3 as a direct target of OsDMI3 and demonstrate its involvement in antioxidant defense.
Assuntos
Oryza , Antioxidantes/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Regulação da Expressão Gênica de Plantas , Oryza/metabolismo , Estresse Oxidativo , Fosforilação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
In rice (Oryza Sativa), Osmotic Stress/ABA-activated Protein Kinase 10 (SAPK10) has been shown to be induced by hyperosmotic stress and abscisic acid (ABA). However, the molecular function of SAPK10 and its downstream targets in ABA-induced antioxidant defense is poorly understood. Here, we identified an unknown function DUF1639 family protein, OsDUF1639.1, which interacts with SAPK10 in vitro and in vivo. OsDUF1639.1 positively regulates ABA responses in seed germination and tolerance to drought stress. We found that SAPK10 directly phosphorylates OsDUF1639.1 at Thr-80 in vitro. The transient expression analysis in combination with mutant analysis in rice protoplasts showed that Thr-80 is essential for ABA-induced stimulation of antioxidant defense by SAPK10. These results suggest that SAPK10 functions upstream of OsDUF1639.1 to regulate the activities of antioxidant enzymes, and Thr-80 phosphorylation of OsDUF1639.1 has a crucial role in ABA-induced antioxidant defense.
Assuntos
Ácido Abscísico , Oryza , Ácido Abscísico/metabolismo , Antioxidantes/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Oryza/metabolismo , Pressão Osmótica , Fosforilação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo , Estresse FisiológicoRESUMO
ZFP36 has been shown to be involved in ABA-induced antioxidant defense and enhance rice tolerance to drought, salt stress and oxidative stress. Using ZFP36 as bait, a yeast two-hybrid system was used to obtain the interacting protein OsDjC46, which belongs to heat shock protein and usually exists in the form of molecular chaperone, was identified. Further Co-IP (co-immunoprecipitation), BiFC (bimolecular fluorescence complement) and GST (glutathione-S-transferase) pull-down experiments verified that ZFP36 interacted with OsDjC46 in vivo and in vitro. Heat shock protein has been shown to increase plant resistance to stresses, but whether OsDjC46 was a key factor in plant response to various stresses has not been reported. Here, various stimuli, such as abscisic acid (ABA), hydrogen peroxidase (H2O2), polyethylene (PEG) and sodium chloride (NaCl) markedly induced the expression of OsDjC46 in the seedlings. Overexpression of OsDjC46 in rice can enhance the tolerance to salinity and drought; in contrast, knockout of OsDjC46 rice plants was more sensitive to salt stress and drought. Further investigation revealed that OsDjC46 could participate in regulating the expression and activities of antioxidant of SOD and CAT under drought and salt stress. Taken together, these findings reveal a novel function of OsDjC46 in adjusting ABA-induced antioxidant defense.
RESUMO
The mitogen-activated protein kinase OsMPK1 is involved in abscisic acid (ABA) biosynthesis in rice (Oryza sativa L.). However, the underlying molecular mechanisms of OsMPK1 in regulating ABA biosynthesis are poorly understood. Here, by using yeast two-hybrid assay and firefly luciferase complementary imaging assay, we show that OsMPK1 physically interact with a short-chain dehydrogenase protein OsABA2. However, OsMPK5, a homolog of OsMPK1, does not interact with OsABA2. Further, OsMPK1 can phosphorylate OsABA2S197 in vitro. Phosphorylation at the position of OsABA2S197 does not affect its subcellular localization, but enhances the stability of OsABA2 protein. We also found that OsABA2 has feedback regulation on OsMPK1 kinase activity. Further research reveals that OsMPK1 and OsABA2 coordinately regulate the biosynthesis of ABA, and phosphorylation of OsABA2 at Ser197 by OsMPK1 plays a crucial role in regulating the biosynthesis of ABA. Finally, genetic analysis showed that OsABA2 can enhance the sensitivity of rice to ABA and the tolerance of rice to drought and salt stress.
Assuntos
Ácido Abscísico/metabolismo , Oxirredutases do Álcool/genética , Proteínas Quinases Ativadas por Mitógeno/genética , Oryza/genética , Proteínas de Plantas/genética , Proteínas Recombinantes/genética , Oxirredutases do Álcool/metabolismo , Secas , Retroalimentação Fisiológica , Regulação da Expressão Gênica de Plantas , Genes Reporter , Isoenzimas/genética , Isoenzimas/metabolismo , Luciferases/genética , Luciferases/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Cebolas/genética , Cebolas/metabolismo , Oryza/metabolismo , Fosforilação , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Processamento de Proteína Pós-Traducional , Estabilidade Proteica , Proteínas Recombinantes/metabolismo , Transdução de Sinais , Estresse Fisiológico , Técnicas do Sistema de Duplo-HíbridoRESUMO
A highly enantioselective isocyanide-based multicomponent reaction catalyzed by a chiral N,N'-dioxide/MgII complex was reported. A wide range of substrates were tolerated in this reaction, including alkyl- and aryl-substituted isocyanides with alkylidene malonates and various phenols, affording the corresponding phenoxyimidate products in good to excellent yields (up to 94% yield) with good to excellent enantioselectivities (up to 95.5:4.5 er). A catalytic cycle and transition state were proposed to rationalize the reaction process and enantiocontrol.
RESUMO
Drought stress seriously limits crop productivity. Although studies have been carried out, it is still largely unknown how plants respond to drought stress. Here we find that drought treatment can enhance the phosphorylation activity of brassinosteroid-signaling kinase 1 (ZmBSK1) in maize (Zea mays). Our genetic studies reveal that ZmBSK1 positively affects drought tolerance in maize plants. ZmBSK1 localizes in plasma membrane, interacts with calcium/calmodulin (Ca2+ /CaM)-dependent protein kinase (ZmCCaMK), and phosphorylates ZmCCaMK. Ser-67 is a crucial phosphorylation site of ZmCCaMK by ZmBSK1. Drought stress enhances not only the interaction between ZmBSK1 and ZmCCaMK but also the phosphorylation of Ser-67 in ZmCCaMK by ZmBSK1. Furthermore, Ser-67 phosphorylation in ZmCCaMK regulates its Ca2+ /CaM binding, autophosphorylation and transphosphorylation activity, and positively affects its function in drought tolerance in maize. Our results reveal an important role for ZmBSK1 in drought tolerance and suggest a direct regulatory mode of ZmBSK1 phosphorylating ZmCCaMK.
Assuntos
Brassinosteroides , Zea mays , Cálcio/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Zea mays/metabolismoRESUMO
Due to global warming and population growth, plants need to rescue themselves, especially in unfavorable environments, to fulfill food requirements because they are sessile organisms. Stress signal sensing is a crucial step that determines the appropriate response which, ultimately, determines the survival of plants. As important signaling modules in eukaryotes, plant mitogen-activated protein kinase (MAPK) cascades play a key role in regulating responses to the following four major environmental stresses: high salinity, drought, extreme temperature and insect and pathogen infections. MAPK cascades are involved in responses to these environmental stresses by regulating the expression of related genes, plant hormone production and crosstalk with other environmental stresses. In this review, we describe recent major studies investigating MAPK-mediated environmental stress responses. We also highlight the diverse function of MAPK cascades in environmental stress. These findings help us understand the regulatory network of MAPKs under environmental stress and provide another strategy to improve stress resistance in crops to ensure food security.
Assuntos
Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fenômenos Fisiológicos Vegetais , Estresse Fisiológico , Adaptação Biológica , Secas , Salinidade , TemperaturaRESUMO
Calcium (Ca2+)/calmodulin (CaM)-dependent protein kinase (CCaMK) is an important positive regulator of abscisic acid (ABA) and abiotic stress signaling in plants and is believed to act upstream of mitogen-activated protein kinase (MAPK) in ABA signaling. However, it is unclear how CCaMK activates MAPK in ABA signaling. Here, we show that OsDMI3, a rice (Oryza sativa) CCaMK, directly interacts with and phosphorylates OsMKK1, a MAPK kinase (MKK) in rice, in vitro and in vivo. OsDMI3 was found to directly phosphorylate Thr-25 in the N-terminus of OsMKK1, and this Thr-25 phosphorylation is OsDMI3-specific in ABA signaling. The activation of OsMKK1 and its downstream kinase OsMPK1 is dependent on Thr-25 phosphorylation of OsMKK1 in ABA signaling. Moreover, ABA treatment induces phosphorylation in the activation loop of OsMKK1, and the two phosphorylations, in the N-terminus and in the activation loop, are independent. Further analyses revealed that OsDMI3-mediated phosphorylation of OsMKK1 positively regulates ABA responses in seed germination, root growth, and tolerance to both water stress and oxidative stress. Our results indicate that OsMKK1 is a direct target of OsDMI3, and OsDMI3-mediated phosphorylation of OsMKK1 plays an important role in activating the MAPK cascade and ABA signaling.
Assuntos
Ácido Abscísico/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Cálcio/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Oryza/enzimologia , Proteínas de Plantas/metabolismo , Ácido Abscísico/farmacologia , Quinases de Proteína Quinase Ativadas por Mitógeno/química , Modelos Biológicos , Oryza/efeitos dos fármacos , Oryza/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Fosfotreonina/metabolismo , Ligação Proteica/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , ÁguaRESUMO
Salinity severely reduces plant growth and limits agricultural productivity. Dynamic changes and rearrangement of the plant cell wall is an important response to salt stress, but relatively little is known about the biological importance of specific cell wall components in the response. Here, we demonstrate a specific function of ß-1,4-galactan in salt hypersensitivity. We found that salt stress induces the accumulation of ß-1,4-galactan in root cell walls by up regulating the expression of GALACTAN SYNTHASE 1 (GALS1), which encodes a ß-1,4-galactan synthase. The accumulation of ß-1,4-galactan negatively affects salt tolerance. Exogenous application of D-galactose (D-Gal) causes an increase in ß-1,4-galactan levels in the wild type and GALS1 mutants, especially in GALS1 overexpressors, which correlated with the aggravated salt hypersensitivity. Furthermore, we discovered that the BARLEY B RECOMBINANT/BASIC PENTACYSTEINE transcription factors BPC1/BPC2 positively regulate plant salt tolerance by repressing GALS1 expression and ß-1,4-galactan accumulation. Genetic analysis suggested that GALS1 is genetically epistatic to BPC1/BPC2 with respect to the control of salt sensitivity as well as accumulation of ß-1,4-galactan. Taken together, our results reveal a new regulatory mechanism by which ß-1,4-galactan regulated by the BPC1/BPC2-GALS1 module aggravates salt sensitivity in Arabidopsis thaliana.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Parede Celular/metabolismo , Galactosiltransferases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Parede Celular/genética , Galactosiltransferases/genética , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismoRESUMO
Soil saline-alkalization is a major environmental stress that impairs plant growth and crop productivity. Plant roots are the primary site for the perception of soil stresses; however, the regulation mechanism engaged in the saline-alkaline stress response in plant roots is not well understood. In this study, we identified how a rice Ca2+/calmodulin-dependent protein kinase, OsDMI3, confers saline-alkaline tolerance in rice root growth. We measured the OsDMI3 activity by an in-gel kinase assay, Na+ content by NaHCO3 treatment, and Na+ and H+ fluxes by noninvasive micro-test technology (NMT). Furthermore, a real-time reverse-transcription polymerase chain reaction (RT-PCR) analysis was performed to identify the genes upregulated in response to NaHCO3 treatment in rice roots. The results showed that NaHCO3 significantly increased OsDMI3 expression and activity in rice roots. This was consistent with the results of Na+ content and NMT that indicated OsDMI3 promoted root elongation under saline-alkaline stress by reducing root Na+ and H+ influx. Moreover, real-time RT-PCR analysis revealed that OsDMI3 up-regulated the transcript levels of OsSOS1 and PM-H+-ATPase genes OsA3 and OsA8 in saline-alkaline stressed rice plants. Collectively, our results suggest that OsDMI3 could promote saline-alkaline tolerance in rice roots by modulating the Na+ and H+ influx. These findings provide an important genetic target for protection of growth in rice exposed to saline-alkaline stress.