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The phytohormone auxin controls plant growth and development via TIR1-dependent protein degradation of canonical AUX/IAA proteins, which normally repress the activity of auxin response transcription factors (ARFs). IAA33 is a non-canonical AUX/IAA protein lacking a TIR1-binding domain, and its role in auxin signaling and plant development is not well understood. Here, we show that IAA33 maintains root distal stem cell identity and negatively regulates auxin signaling by interacting with ARF10 and ARF16. IAA33 competes with the canonical AUX/IAA repressor IAA5 for binding to ARF10/16 to protect them from IAA5-mediated inhibition. In contrast to auxin-dependent degradation of canonical AUX/IAA proteins, auxin stabilizes IAA33 protein via MITOGEN-ACTIVATED PROTEIN KINASE 14 (MPK14) and does not affect IAA33 gene expression. Taken together, this study provides insight into the molecular functions of non-canonical AUX/IAA proteins in auxin signaling transduction.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/farmacologia , Proteínas Nucleares/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Proteínas Nucleares/genética , Fosforilação , Reguladores de Crescimento de Plantas/farmacologia , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Proteólise , Transdução de SinaisRESUMO
Drought stress globally poses a significant threat to maize (Zea mays L.) productivity and the underlying molecular mechanisms of drought tolerance remain elusive. In this study, we characterized ZmbHLH47, a basic helix-loop-helix (bHLH) transcription factor, as a positive regulator of drought tolerance in maize. ZmbHLH47 expression was notably induced by both drought stress and abscisic acid (ABA). Transgenic plants overexpressing ZmbHLH47 displayed elevated drought tolerance and ABA responsiveness, while the zmbhlh47 mutant exhibited increased drought sensitivity and reduced ABA sensitivity. Mechanistically, it was revealed that ZmbHLH47 could directly bind to the promoter of ZmSnRK2.9 gene, a member of the subgroup III SnRK2 kinases, activating its expression. Furthermore, ZmSnRK2.9-overexpressing plants exhibited enhanced ABA sensitivity and drought tolerance, whereas the zmsnrk2.9 mutant displayed a decreased sensitivity to both. Notably, overexpressing ZmbHLH47 in the zmsnrk2.9 mutant closely resembled the zmsnrk2.9 mutant, indicating the importance of the ZmbHLH47-ZmSnRK2.9 module in ABA response and drought tolerance. These findings provided valuable insights and a potential genetic resource for enhancing the environmental adaptability of maize.
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Ácido Abscísico , Secas , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Estresse Fisiológico , Zea mays , Zea mays/genética , Zea mays/fisiologia , Zea mays/metabolismo , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Plantas Geneticamente Modificadas/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Resistência à SecaRESUMO
The cytokinin response factors (CRFs) are pivotal players in regulating plant growth, development, and responses to diverse stresses. Despite their significance, comprehensive information on CRF genes in the primary food crop, maize, remains scarce. In this study, a genome-wide analysis of CRF genes in maize was conducted, resulting in the identification of 12 members. Subsequently, we assessed the chromosomal locations, gene duplication events, evolutionary relationships, conserved motifs, and gene structures of all ZmCRF members. Analysis of ZmCRF promoter regions indicated the presence of cis-regulatory elements associated with plant growth regulation, hormone response, and various abiotic stress responses. The expression patterns of maize CRF genes, presented in heatmaps, exhibited distinctive patterns of tissue specificity and responsiveness to multiple abiotic stresses. qRT-PCR experiments were conducted on six selected genes and confirmed the involvement of ZmCRF genes in the plant's adaptive responses to diverse environmental challenges. In addition, ZmCRF9 was demonstrated to positively regulate cold and salt tolerance. Ultimately, we explored the putative interaction partners of ZmCRF proteins. In summary, this systematic overview and deep investigation of ZmCRF9 provides a solid foundation for further exploration into how these genes contribute to the complex interplay of plant growth, development, and responses to stress.
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Regulação da Expressão Gênica de Plantas , Família Multigênica , Proteínas de Plantas , Estresse Fisiológico , Zea mays , Zea mays/genética , Zea mays/metabolismo , Estresse Fisiológico/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Filogenia , Genoma de Planta , Regiões Promotoras Genéticas , Citocininas/metabolismo , Estudo de Associação Genômica Ampla , Duplicação GênicaRESUMO
BACKGROUND: The structural basis of chloroplast and the regulation of chloroplast biogenesis remain largely unknown in maize. Gene mutations in these pathways have been linked to the abnormal leaf color phenotype observed in some mutants. Large scale structure variants (SVs) are crucial for genome evolution, but few validated SVs have been reported in maize and little is known about their functions though they are abundant in maize genomes. RESULTS: In this research, a spontaneous maize mutant, pale green leaf-shandong (pgl-sd), was studied. Genetic analysis showed that the phenotype of pale green leaf was controlled by a recessive Mendel factor mapped to a 156.8-kb interval on the chromosome 1 delineated by molecular markers gy546 and gy548. There were 7 annotated genes in this interval. Reverse transcription quantitative PCR analysis, SV prediction, and de novo assembly of pgl-sd genome revealed that a 137.8-kb deletion, which was verified by Sanger sequencing, might cause the pgl-sd phenotype. This deletion contained 5 annotated genes, three of which, including Zm00001eb031870, Zm00001eb031890 and Zm00001eb031900, were possibly related to the chloroplast development. Zm00001eb031870, encoding a Degradation of Periplasmic Proteins (Deg) homolog, and Zm00001eb031900, putatively encoding a plastid pyruvate dehydrogenase complex E1 component subunit beta (ptPDC-E1-ß), might be the major causative genes for the pgl-sd mutant phenotype. Plastid Degs play roles in protecting the vital photosynthetic machinery and ptPDCs provide acetyl-CoA and NADH for fatty acid biosynthesis in plastids, which were different from functions of other isolated maize leaf color associated genes. The other two genes in the deletion were possibly associated with DNA repair and disease resistance, respectively. The pgl-sd mutation decreased contents of chlorophyll a, chlorophyll b, carotenoids by 37.2%, 22.1%, and 59.8%, respectively, and led to abnormal chloroplast. RNA-seq revealed that the transcription of several other genes involved in the structure and function of chloroplast was affected in the mutant. CONCLUSIONS: It was identified that a 137.8-kb deletion causes the pgl-sd phenotype. Three genes in this deletion were possibly related to the chloroplast development, which may play roles different from that of other isolated maize leaf color associated genes.
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Proteínas de Plantas , Zea mays , Zea mays/genética , Zea mays/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Clorofila A/metabolismo , Fotossíntese/genética , Clorofila/metabolismo , Cloroplastos/genética , Cloroplastos/metabolismo , Fenótipo , Folhas de Planta/metabolismo , Mutação , Regulação da Expressão Gênica de PlantasRESUMO
Cytokinins are phytohormones that regulate plant development, growth, and responses to stress. In particular, cytokinin has been reported to negatively regulate plant adaptation to high salinity; however, the molecular mechanisms that counteract cytokinin signaling and enable salt tolerance are not fully understood. Here, we provide evidence that salt stress induces the degradation of the cytokinin signaling components Arabidopsis (Arabidopisis thaliana) response regulator 1 (ARR1), ARR10 and ARR12. Furthermore, the stress-activated mitogen-activated protein kinase 3 (MPK3) and MPK6 interact with and phosphorylate ARR1/10/12 to promote their degradation in response to salt stress. As expected, salt tolerance is decreased in the mpk3/6 double mutant, but enhanced upon ectopic MPK3/MPK6 activation in an MKK5DD line. Importantly, salt hypersensitivity phenotypes of the mpk3/6 line were significantly alleviated by mutation of ARR1/12. The above results indicate that MPK3/6 enhance salt tolerance in part via their negative regulation of ARR1/10/12 protein stability. Thus, our work reveals a new molecular mechanism underlying salt-induced stress adaptation and the inhibition of plant growth, via enhanced degradation of cytokinin signaling components.
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Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Proteína Quinase 3 Ativada por Mitógeno , Tolerância ao Sal/genéticaRESUMO
In plant cells, multiple paralogs from ribosomal protein (RP) families are always synchronously expressed, which is likely contributing to ribosome heterogeneity or functional specialization. However, previous studies have shown that most RP mutants share common phenotypes. Consequently, it is difficult to distinguish whether the phenotypes of the mutants have resulted from the loss of specific genes or a global ribosome deficiency. Here, to investigate the role of a specific RP gene, we employed a gene overexpression strategy. We found that Arabidopsis lines overexpressing RPL16D (L16D-OEs) display short and curled rosette leaves. Microscopic observations reveal that both the cell size and cell arrangement are affected in L16D-OEs. The severity of the defect is positively correlated with RPL16D dosage. By combining transcriptomic and proteomic profiling, we found that overexpressing RPL16D decreases the expression of genes involved in plant growth, but increases the expression of genes involved in immune response. Overall, our results suggest that RPL16D is involved in the balance between plant growth and immune response.
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Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteômica , Folhas de Planta/metabolismo , Regulação da Expressão Gênica de Plantas , FenótipoRESUMO
Uneven germination is still a common problem in sweet maize planting. The mesocotyl is a key driver for ground-breaking sweet maize, and deep-sowing has a longer mesocotyl. However, the physiological and molecular mechanisms of sweet maize mesocotyl elongation in response to deep-sowing remain unknown. Here we found that sweet maize inbred line Ltx05 could obtain longer mesocotyls in deep soil of 10 cm depth, and that 20 mg/L GA3 was the optimal concentration to promote mesocotyl elongation and seedling emergence. Microstructure observation showed that the longitudinal cell length of mesocotyl at 10 cm sowing depth was significantly longer than that of 1 cm. Transcriptome analysis showed that microtubule process related differentially expressed genes may contribute to the longitudinal cell elongation. The content of GAs in the mesocotyl at 10 cm sowing depth was markedly higher than that of 1 cm. Combining transcriptome data and qRT-PCR at different developmental stages, ZmGA20ox1, ZmGA20ox4 and ZmGA20ox5 were identified as three positive regulation candidate genes during mesocotyl elongation under deep-sowing conditions, and this was further confirmed by the significant elongation of the hypocotyl in heterologous transformation of Arabidopsis thaliana. These results lay a foundation for improving the ability of sweet maize to tolerate deep-sowing stress and improving the breeding of excellent deep-sowing-tolerant germplasms.
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KEY MESSAGE: Plant growth is greatly inhibited in tightly sealed Petri dishes for lack of CO2. Bacteria which co-cultured with plant can produce CO2 to promote plant growth in sealed systems. Bacteria produce a wide variety of volatiles, some of which can support and others can damage plant growth. It is a controversial issue whether CO2 or other bacterial volatile compounds promote plant growth in sealed systems. CO2 is critical for photosynthesis. Here, we show that CO2 is a key constituent of the plant growth-promoting volatiles generated by bacteria in a sealed system. We revealed that the growth of Arabidopsis seedlings in an airtight container was retarded due to insufficient supply of the CO2. When either CO2 was introduced into the container, or the seedlings were co-cultured along with certain bacterial species, the plants' growth was restored. CONCLUSION: The benefit of co-culturing was largely due to the CO2 generated by respiration of the bacteria.
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Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Dióxido de Carbono/metabolismo , Ar , Arabidopsis/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Clorofila/metabolismo , Escherichia coli/metabolismo , Permeabilidade , Pseudomonas syringae/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Serratia marcescens/metabolismo , Compostos Orgânicos VoláteisRESUMO
Persistent lesion mimic can cause leaf senescence, affecting grain yield in crops. However, knowledge about the regulation of lesion mimic and leaf senescence in crop plants is still limited. Here, we report that the amino acid transporter OsAAP3, a negative regulator of tiller bud elongation and rice grain yield, is involved in lesion mimic and leaf senescence. Altered expression of OsAAP3 can initiate the nitric oxide signaling pathway through excessive accumulation of arginine in rice leaves, influencing ROS accumulation, antioxidant enzymes activities, proline concentration, and malondialdehyde concentration. This finally triggers cell death which ultimately leads to lesion mimic and leaf senescence by regulating the degradation of chloroplast and the expression abundance of components in the photosynthetic pathway. Overall, the results not only provide initial insights into the regulatory role of amino acid transport genes in rice growth and development, but also help to understand the factors regulating the leaf senescence.
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Arginina/metabolismo , Oryza/fisiologia , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Sistemas de Transporte de Aminoácidos/genética , Sistemas de Transporte de Aminoácidos/metabolismo , Transporte Biológico/genética , Morte Celular/genética , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Óxido Nítrico/metabolismo , Oryza/genética , Fotossíntese/genética , Folhas de Planta/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Espécies Reativas de Oxigênio/metabolismo , Metabolismo Secundário/genéticaRESUMO
During embryogenesis and organ formation, establishing proper gradient is critical for auxin function, which is achieved through coordinated regulation of both auxin metabolism and transport. Expression of auxin biosynthetic genes is often tissue specific and is regulated by environmental signals. However, the underlying regulatory mechanisms remain elusive. Here, we investigated the transcriptional regulation of a key auxin biosynthetic gene, l-Tryptophan aminotransferase of Arabidopsis1 (TAA1). A canonical and a novel Arabidopsis (Arabidopsis thaliana) response regulator (ARR) binding site were identified in the promoter and the second intron of TAA1, which were required for its tissue-specific expression. C-termini of a subset of the type B ARRs selectively bind to one or both cis elements and activate the expression of TAA1 We further demonstrated that the ARRs not only mediate the transcriptional regulation of TAA1 by cytokinins, but also mediate its regulation by ethylene, light, and developmental signals. Through direct protein-protein interactions, the transcriptional activity of ARR1 is enhanced by ARR12, DELLAs, and ethylene-insenstive3 (EIN3). Our study thus revealed the ARR proteins act as key node that mediate the regulation of auxin biosynthesis by various hormonal, environmental, and developmental signals through transcriptional regulation of the key auxin biosynthesis gene TAA1.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Transcrição Gênica , Arabidopsis/efeitos dos fármacos , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Sequência de Bases , Citocininas/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Mutação/genética , Regiões Promotoras Genéticas , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/efeitos da radiação , Transdução de Sinais/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/efeitos da radiaçãoRESUMO
Extraction of valuable metals besides silica from high-alumina fly ash is one of the most important high-value utilization pathways. However, it is difficult to realize high-efficiency extraction due to the stable structure e.g. of quartz and mullite. In this paper, mineral phase transformation for valuable metal recovery and mesoporous silica in situ preparation from fly ash by a selective acid leaching method was proposed. The mineral phase transformation, dissolution behavior of each metal, and pore structure of fly ash derived mesoporous silica were systematically investigated. The results show that the co-activation of fly ash by Na2CO3-K2CO3 formed the phases of kalsilite and (Na, K)AlSiO4. During the acid leaching process, Al, Li, and Ga could be leached with the efficiencies of 86.17%, 89%, and 80% in the FK system. In the FN system, the efficiencies of Al, Li, and Ga are 92.38%, 95%, and 83%, respectively. The crystal plane (002) was destroyed for kaliophilite while all the crystal planes were destroyed for nepheline. With the increase of HCl solution concentration, the porous silica exhibited the same change order of pore shape. The pore structure of as-prepared porous silica was type IV and the hysteresis loop was type H3, and the specific surface areas could be 565.54, 448.02, and 746.76 m2 g-1, respectively. Finally, the leaching liquors can be used to produce crystal aluminum chloride, lithium carbonate and gallium. This paper might provide technical support for full recycling of high-value resources from fly ash.
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Nitrogen, as an essential nutrient, largely contributes to the coastal eutrophication. However, the accurate depiction and evaluation of how external loadings, hydrodynamics, and biogeochemical reactions mediate the occurrence, transport, and transformation of nitrate (NO3-) within coastal embayment still pose ongoing challenges to date. In this study, we took advantage of dual isotopes of NO3- to track external NO3- loadings, radium and dual isotopes of H2O to characterize the influences of hydrodynamic on NO3- transport, δ18O-NO3- and δ18O-H2O along with microbial analysis to explore major NO3- biogeochemical reactions in Tolo Harbour, Hong Kong. The multiple isotopic evidence showed that NO3- in surface harbour water was predominantly contributed by precipitation in wet season and its impact was strengthened by stratification. In dry season, NO3- in the surface harbour water became largely influenced by benthic input and biogeochemical reactions due to intensified vertical mixing. Based on NO3- mass balance model, biogeochemical reaction, especially nitrification, was found to be the major process to secure the closure of NO3- budget and increase NO3- inventory from wet to dry season. Hydrodynamics redistributed the external NO3- loadings and mediated nitrogen biogeochemical reactions, both of which further synergistically regulated the fate of NO3- in the embayment.
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Estuaries are hotspots where terrestrially originated dissolved organic matter (DOM) is modified in molecular composition before entering marine environments. However, very few research has considered nitrogen (N) modifications of DOM molecules in estuaries, limiting our understanding of dissolved organic nitrogen (DON) cycling and the associated carbon cycling in estuaries. This study integrated optical, stable isotopes (δ15N and δ13C) and molecular composition (FT-ICR MS) to characterize the transformation of DOM in the Yangtze River Estuary. Both concentration of dissolved organic carbon (DOC) and DON decreased with increasing salinity, while their δ13C and δ15N increased with the increasing salinity. A significant positive correlation was found between δ15N and δ13C during the transportation of DOM to marginal seas, indicating that the behavior of both DOC and DON are primarily controlled by the mixing of freshwater and the seawater in the YRE. During the mixing process, the DON addition was observed using the conservative mixing curves. In the view of molecular composition, DOM molecules became more aromatic as the number of N atoms increased. Spearman correlations reveal that DOM molecules with fewer N atoms exhibited a higher enrichment in protein-like components, while those with more N atoms were more enriched in humic-like components. In addition, the δ15N and δ13C tended to increase as the N content of DOM decreased. Therefore, DON molecules with fewer N atoms were likely to be transformed into those with more N atoms based on the isotopic fractionation theory. This study establishes a linkage between the molecular composition and the δ15N of DOM, and discovers the N transformation pattern within DOM molecules during the transportation to marginal seas.
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Matéria Orgânica Dissolvida , Nitrogênio , Isótopos de Nitrogênio/análise , Oceanos e Mares , Nitrogênio/análise , Estuários , Rios/químicaRESUMO
Water splitting is an important way to obtain hydrogen applied in clean energy, which mainly consists of two half-reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the kinetics of the OER of water splitting, which occurs at the anode, is slow and inefficient, especially in acid. Currently, the main OER catalysts are still based on noble metals, such as Ir and Ru, which are the main active components. Hence, the exploration of new OER catalysts with low cost, high activity, and stability has become a key issue in the research of electrolytic water hydrogen production technology. In this paper, the reaction mechanism of OER in acid was discussed and summarized, and the main methods to improve the activity and stability of non-noble metal OER catalysts were summarized and categorized. Finally, the future prospects of OER catalysts in acid were made to provide a little reference idea for the development of advanced OER catalysts in acid in the future.
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Analyzing the molecular composition change of dissolved organic matter (DOM) during transportation in estuaries can enhance our understanding of the fate of DOM. However, the impact of hydrologic conditions resulting from large river plumes on the DOM cycle are less explored, and previous studies were insufficient to capture the molecular fate that occur during the transportation process. In this study, we used a range of bulk and optical techniques, as well as Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), to determine the concentration and characteristics of DOM along two trajectories of downstream plumes of diluted water of the Yangtze (Changjiang) River estuary (YRE) during the high discharge season. These two plumes situated along the route of the summer Changjiang diluted water (CDW) have been identified and named CDW-North (CDW-N) and CDW-South (CDW-S), respectively. Despite having the same riverine end-member origin, the turbidity zone in YRE significantly modifies the molecular characteristics and composition of DOM. The results of FT-ICR MS indicated a spatial variation of DOM composition in the coastal zone of the two plumes. The relative intensities of the CHO, CHOS, and CHONS compounds are negatively correlated with salinity. In addition, the coastal zones of both CDW-N and CDW-S are characterized by more autochthonous DOM sources. More CHON compounds in CDW-N are probably due to the production of autochthonous DOM in offshore waters. The activity of phytoplankton increased the surface dissolved oxygen level of CDW-N in the coastal zone. However, the hypoxic zone formed at the bottom of the CDW-N due to microbial degradation of organic matter and may further benefit the preservation of CHON compounds. Our study emphasizes that the characteristics and composition of the estuarine DOM can be significantly shaped by distinct large river plumes. Furthermore, using FT-ICR MS in combination with complementary techniques can better assist in identifying the sources and transformation mechanisms of estuarine DOM in large river plume-affected systems and provide more valuable insights into the role of DOM in the estuarine biogeochemical cycle.
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Understanding the molecular composition and fate of dissolved organic matter (DOM) during transport in estuaries is essential for gaining a comprehensive understanding of its role within the global biogeochemical cycle. In 2020, a catastrophic flood occurred in the Yangtze River basin. It is currently unknown whether differences in hydrologic conditions due to extreme flooding will significantly impact the estuarine to oceanic DOM cycle. We determined the DOM composition in the Yangtze River estuary (YRE) to the East China Sea by using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) during the high discharge and the flood period (monthly average discharge was 1.2 times higher) on the same trajectory. Our study found that the composition of DOM is more diverse, and more DOM molecules were introduced to the YRE during the flood, especially in the freshwater end member. The result revealed that the DOM was significantly labile and unstable during the flood period. A total of 1840 unique molecular formulas were identified during the flood period, most of which were CHON, CHONS, and CHOS compounds, most likely resulting from anthropogenic inputs from upstream. Only 194 of these molecules were detected in the seawater end member after transporting to the sea, suggesting that the YRE served as a 'filter' of DOM. However, the flood enhances the transport of a group of terrigenous DOM, that is resistant to photodegradation and biodegradation. As a result, YRE experienced ~1.6 times higher terrigenous DOC flux than high discharge period. Considering the increased frequency of future floods, our study provides a preliminary basis for further research on how floods affect the composition and characteristics of estuarine DOM. With the help of the FT-ICR MS technique, we can now better understand the dynamic of DOM composition and characteristics in large river estuaries.
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Designing and developing suitable oxygen evolution reaction (OER) catalysts with high activity and stability remain challenging in electrolytic water splitting. Hence, NiFe@NC@MoS2 core-bishell composites wrapped by molybdenum disulphide (MoS2) and nitrogen-doped graphene (NC) were prepared using hydrothermal synthesis in this research. NiFe@NC@MoS2 composite exhibits excellent performance with an overpotential of 288 mV and a Tafel slope of 53.2 mV·dec-1 at a current density of 10 mA·cm-2 in 1 M KOH solution, which is superior to commercial RuO2. NC and MoS2 bishells create profuse edge active sites that enhance the adsorption ability of OOH* while lowering the overall overpotential of the product and improving its oxygen precipitation performance. The density function theory(DFT) analysis confirms that the layered MoS2 in NiFe@NC@MoS2 provides additional edge active sites and enhances electron transfer, thus increasing the intrinsic catalytic activity. This research paves a novel way for developing OER electrocatalysts with excellent catalytic performance.
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Maize is the most important cereal crop globally. However, in recent years, maize production faced numerous challenges from environmental factors due to the changing climate. Salt stress is among the major environmental factors that negatively impact crop productivity worldwide. To cope with salt stress, plants developed various strategies, such as producing osmolytes, increasing antioxidant enzyme activity, maintaining reactive oxygen species homeostasis, and regulating ion transport. This review provides an overview of the intricate relationships between salt stress and several plant defense mechanisms, including osmolytes, antioxidant enzymes, reactive oxygen species, plant hormones, and ions (Na+, K+, Cl-), which are critical for salt tolerance in maize. It addresses the regulatory strategies and key factors involved in salt tolerance, aiming to foster a comprehensive understanding of the salt tolerance regulatory networks in maize. These new insights will also pave the way for further investigations into the significance of these regulations in elucidating how maize coordinates its defense system to resist salt stress.
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The growth and productivity of maize (Zea mays), along with other crop plants, can be significantly hindered by salt stress. Nevertheless, the precise molecular mechanism underlying salt tolerance in maize has yet to be fully elucidated. Hence, it was attempted to identify ZmIAA9, a member of the maize Aux/IAA gene family, as a positive regulator of salt tolerance in maize, which was accompanied by the increased ROS detoxification and elevated transcript abundances of ROS scavenging genes. Molecular and biochemical assays have provided compelling evidence that ZmbHLH32, a transcription factor belonging to the bHLH family, was capable of binding directly to the promoter region of ZmIAA9, thereby activating its expression. This interaction between ZmbHLH32 and ZmIAA9 could be critical for the regulation of salt tolerance in maize. As expected, overexpression of ZmbHLH32 led to the enhanced salt tolerance. In contrast, decreased salt tolerance was attained after application of knockout mutants of ZmbHLH32. Furthermore, ZmARF1, which could act as a downstream of ZmIAA9, was found to physically interact with ZmIAA9 and repress the expression levels of ROS scavenging genes. Thus, our work uncovers a novel mechanism of ZmbHLH32-ZmIAA9-ZmARF1 module-mediated salt tolerance in maize, which can be exploited for breeding salt-tolerant maize varieties.
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Tolerância ao Sal , Zea mays , Tolerância ao Sal/genética , Espécies Reativas de Oxigênio/metabolismo , Melhoramento Vegetal , Fatores de Transcrição/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genéticaRESUMO
Marginal seas play a crucial role in the cycling of dissolved organic nitrogen (DON) between the terrestrial and marine environments. However, very few studies have considered the molecular transformation of DON in marginal seas, leaving the DON molecular modifications in its cycling largely unknown. Therefore, this study examined DON cycling in the Bohai Sea and Yellow Sea, two semi-closed marginal seas in northern China, using stable isotopes (δ15N and δ13C), optical characteristics, and molecular compositions. Compared to the Yellow Sea, the Bohai Sea had a weaker exchange with the open ocean, resulting in higher concentrations, lower δ15N, and more recalcitrant properties in DON. The DON cycling showed significant differences inside and outside the Yellow Sea Cold Water (YSCW). Degradation was the major sink of DON in the YSCW, during which more highly unsaturated compounds and carboxyl-rich alicyclic molecules were produced. Nitrogen atoms were found to be removed from the molecules with more N atoms to those with fewer ones during the DON degradation. This study discovered the molecular modifications in DON cycling and highlighted the intrinsic mechanisms in the cycling of DON in marginal seas.