RESUMO
Cadmium (Cd) is a dispensable element that can be absorbed by crops, posing a threat to human health through the food chains. Melatonin (MT), as a plant growth regulator, has been used to alleviate Cd toxicity in many plant species; however, the underlying molecular mechanisms responsible for Cd toxicity in wheat are still poorly understood. In this study, the suitable exogenous MT concentration (50 µM) was screened to mitigate Cd toxicity of wheat plants by increasing the plant height, root length, fresh or dry weight and chlorophyll content, or decreasing the malondialdehyde (MDA) content. In addition, MT application significantly increased ascorbic acid (ASA) and glutathione (GSH) content by reducing ROS production, especially in roots, further decreasing Cd content in fraction of organelles. Moreover, the expression levels of ASA-GSH synthesis genes, APX, GR, and GST were significantly increased by 171.5%, 465.2%, and 256.8% in roots, respectively, whereas GSH, DHAR, or MDHAR were significantly decreased by 48.5%, 54.3%, or 60.0% in roots under MT + Cd stress. However, the expression levels of Cd-induced metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, and TaLCT1 were significantly decreased by 53.7%, 50.1%, 86.5%, 87.2%, and 94.5% in roots under MT + Cd stress compared with alone Cd treatment, respectively. In conclusion, our results suggesting that MT alleviate Cd toxicity in wheat by enhancing ASA-GSH metabolism, suppressing Cd transporter gene expression, and regulating Cd uptake and translocation in wheat plants.
Assuntos
Ácido Ascórbico , Melatonina , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Ácido Ascórbico/metabolismo , Ácido Ascórbico/farmacologia , Cádmio/metabolismo , Cádmio/toxicidade , Glutationa/metabolismo , Humanos , Melatonina/metabolismo , Melatonina/farmacologia , Estresse Oxidativo , Raízes de Plantas/metabolismo , Plântula/metabolismo , Triticum/metabolismoRESUMO
Melatonin (MT) is involved in various physiological processes and stress responses in animals and plants. However, little is known about the molecular mechanisms by which MT regulates potassium deficiency (DK) tolerance in crops. In this study, an appropriate concentration (50 µmol/L) was found to enhance the tolerance of wheat plants against DK. RNA-seq analysis showed that a total of 6253 and 5873 differentially expressed genes (DEGs) were separately identified in root and leaf tissues of the DK + MT-treated wheat plants. They functionally involved biological processes of secondary metabolite, signal transduction, and transport or catabolism. Of these, an upregulated high-affinity K transporter 1 (TaHAK1) gene was next characterized. TaHAK1 overexpression markedly enhanced the K absorption, while its transient silencing exhibited the opposite effect, suggesting its important role in MT-mediated DK tolerance. Moreover, yeast one-hybrid (Y1H) was used to screen the upstream regulators of TaHAK1 gene and the transcription factor TaNAC71 was identified. The binding between TaNAC71 and TaHAK1 promoter was evidenced by using Y1H, LUC, and EMSA assays. Transient overexpression of TaNAC71 in wheat protoplasts activated the TaHAK1 expression, whereas its transient silencing inhibited the TaHAK1 expression and aggravated the sensitivity to DK. Exogenous MT application greatly upregulated the expression of TaHAK1 in both transient overexpression and silencing systems. Our findings revealed some molecular mechanisms underlying MT-mediated DK tolerance and helped broaden its practical application in agriculture.
Assuntos
Proteínas de Transporte de Cátions/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Melatonina/metabolismo , Proteínas de Plantas/metabolismo , Deficiência de Potássio/metabolismo , Triticum/metabolismo , Adaptação Fisiológica/fisiologia , Produtos Agrícolas/metabolismo , Reguladores de Crescimento de Plantas/metabolismoRESUMO
Glutathione S-transferase (GST) is the key enzyme in glutathione (GSH) synthesis, and plays a crucial role in copper (Cu) detoxification. Nonetheless, its regulatory mechanisms remain largely unclear. In this study, we identified a Cu-induced glutathione S-transferase 1 (TaGST1) gene in wheat. Yeast one-hybrid (Y1H) screened out TaWRKY74, which was one member from the WRKY transcription factor family. The bindings between TaGST1 promoter and TaWRKY74 were further verified by using another Y1H and luciferase assays. Expression of TaWRKY74 was induced more than 30-folds by Cu stress. Functions of TaWRKY74 were tested by using transiently silence methods. In transiently TaWRKY74-silenced wheat plants, TaWRKY74 and TaGST1 expression, GST activity, and GSH content was significantly inhibited by 25.68%, 19.88%, 27.66%, and 12.68% in shoots, and 53.81%, 52.11%, 23.47%, and 17.11% in roots, respectively. However, contents of hydrogen peroxide, malondialdehyde, or Cu were significantly increased by 2.58%, 12.45%, or 37.74% in shoots, and 25.24%, 53.84%, and 103.99% in roots, respectively. Notably, exogenous application of GSH reversed the adverse effects of transiently TaWRKY74-silenced wheat plants during Cu stress. Taken together, our results suggesting that TaWRKY74 regulated TaGST1 expression and affected GSH accumulation under Cu stress, and could be useful to ameliorate Cu toxicity for crop food safety.
Assuntos
Cobre/toxicidade , Glutationa Transferase/metabolismo , Glutationa/metabolismo , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Triticum/efeitos dos fármacos , Fatores de Transcrição/genética , Triticum/genética , Triticum/metabolismo , Técnicas do Sistema de Duplo-Híbrido , Leveduras/genéticaRESUMO
Cadmium (Cd), a toxic heavy metal, is harmful to plants and human health. Glutathione (GSH) could alleviate Cd toxicity of plant species, whereas its mechanism responsible for wheat remains poorly understood. Here, we found that exogenous GSH application significantly increased the fresh and dry weight, root elongation, chlorophyll contents, while decreased the contents of malondialdehyde (MDA) and GSH, and translocation factor of Cd compared with Cd treatment. Moreover, GSH application significantly increased activities of antioxidant enzymes and expression of related genes, which involved in GSH synthesis, especially in roots. In addition, we found that GSH application suppressed Cd-induced expression of metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1 and TaIRT2 in roots. Taken together, our results suggested that GSH could alleviate Cd toxicity in wheat by increasing GSH synthesis gene expression or suppressing Cd transporter genes expression, and further affecting Cd uptake and translocation in wheat plants.
Assuntos
Cádmio , Triticum , Antioxidantes , Cádmio/toxicidade , Clorofila , Glutationa , Humanos , Raízes de PlantasRESUMO
BACKGROUND: Drought is one of the most adverse environmental factors limiting crop productions and it is important to identify key genetic determinants for food safety. Calcium-dependent protein kinases (CPKs) are known to be involved in plant growth, development, and environmental stresses. However, biological functions and regulatory mechanisms of many plant CPKs have not been explored. In our previous study, abundance of the wheat CPK34 (TaCPK34) protein was remarkably upregulated in wheat plants suffering from drought stress, inferring that it could be involved in this stress. Therefore, here we further detected its function and mechanism in response to drought stress. RESULTS: Transcripts of the TaCPK34 gene were significantly induced after PEG-stimulated water deficiency (20% PEG6000) or 100 µM abscisic acid (ABA) treatments. The TaCPK34 gene was transiently silenced in wheat genome by using barley stripe mosaic virus-induced silencing (BSMV-VIGS) method. After 14 days of drought stress, the transiently TaCPK34-silenced wheat seedlings showed more sensitivity compared with control, and the plant biomasses and relative water contents significantly decreased, whereas soluble sugar and MDA contents increased. The iTRAQ-based quantitative proteomics was employed to measure the protein expression profiles in leaves of the transiently TaCPK34-silenced wheat plants after drought stress. There were 6103 proteins identified, of these, 51 proteins exhibited significantly altered abundance, they were involved in diverse function. And sequence analysis on the promoters of genes, which encoded the above identified proteins, indicated that some promoters harbored some ABA-responsive elements. We determined the interactions between TaCPK34 and three identified proteins by using bimolecular fluorescent complementation (BiFC) method and our data indicated that TaCPK34directly interacted with the glutathione S-transferase 1 and prx113, respectively. CONCLUSIONS: Our study suggested that the TaCPK34 gene played positive roles in wheat response to drought stress through directly or indirectly regulating the expression of ABA-dependent manner genes, which were encoding identified proteins from iTRAQ-based quantitative proteomics. And it could be used as one potential gene to develop crop cultivars with improved drought tolerance.
Assuntos
Secas , Triticum , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Triticum/genética , Triticum/metabolismoRESUMO
Whilst WRKY transcription factors are known to be involved in diverse plant responses to biotic stresses, their involvement in abiotic stress tolerance is poorly understood. OsFRDL4, encoding a citrate transporter, has been reported to be regulated by ALUMINUM (Al) RESISTANCE TRANSCRIPTION FACTOR 1 (ART1) in rice, but whether it is also regulated by other transcription factors is unknown. We define the role of OsWRKY22 in response to Al stress in rice by using mutation and transgenic complementation assays, and characterize the regulation of OsFRDL4 by OsWRKY22 via yeas one-hybrid, electrophoretic mobility shift assay and ChIP-quantitative PCR. We demonstrate that loss of OsWRKY22 function conferred by the oswrky22 T-DNA insertion allele causes enhanced sensitivity to Al stress, and a reduction in Al-induced citrate secretion. We next show that OsWRKY22 is localized in the nucleus, functions as a transcriptional activator and is able to bind to the promoter of OsFRDL4 via W-box elements. Finally, we find that both OsFRDL4 expression and Al-induced citrate secretion are significantly lower in art1 oswrky22 double mutants than in the respective single mutants. We conclude that OsWRKY22 promotes Al-induced increases in OsFRDL4 expression, thus enhancing Al-induced citrate secretion and Al tolerance in rice.
Assuntos
Alumínio/toxicidade , Proteínas de Transporte/metabolismo , Ácido Cítrico/metabolismo , Oryza/genética , Fatores de Transcrição/metabolismo , Proteínas de Transporte/genética , Oryza/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Estresse Fisiológico , Fatores de Transcrição/genéticaRESUMO
The APETALA2/ethylene response factor (AP2/ERF) superfamily is involved in the responses of plants to biotic and abiotic stresses; however, the functions and mechanisms of some members of this family in plants are unclear. In our previous study, expression of TaERFL1a, a member of the AP2/ERF family, was remarkably induced in wheat seedlings suffering freezing stress. In this study, we show that its expression was rapidly upregulated in response to salt, cold, and water deficiency, suggesting roles in the responses to abiotic stresses. Further, transient barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) resulted in significantly reduced tolerance to 20% PEG6000-stimulated water deficiency. Subcellular localization and transcriptional activation assays separately showed that TaERFL1a was targeted to the nucleus and possessed transcriptional activation activity. Yeast two-hybrid library screening identified six interacting proteins, and of these, the interactions between TaERFL1a and TaSGT1, and TaERFL1a and TaDAD2 proteins were further confirmed by yeast co-transformation and bimolecular fluorescent complementation (BiFC). Collectively, our results suggest that TaERFL1a is a stress-responsive transcription factor, which could be functionally related to proteins involved in the abiotic stress responses of plants.
Assuntos
Secas , Proteínas de Plantas/genética , Estresse Fisiológico , Fatores de Transcrição/genética , Triticum/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Fatores de Transcrição/metabolismo , Triticum/metabolismoRESUMO
BACKGROUND: Mercury (Hg) is not only a threat to public health but also a growth risk factor to plants, as it is readily accumulated by higher plants. Accumulation of Hg in plants disrupts many cellular-level functions and inhibits growth and development; however, the detoxification and tolerance mechanisms of plants to Hg stress are still not fully understood. Exposure to toxic Hg also occurs in some crops cultivated under anoxic conditions, such as rice (Oryza sativa L.), a model organism and one of the most important cultivated plants worldwide. In this study, we functionally characterized a rice translationally controlled tumor protein gene (Os11g43900, OsTCTP) involved in Hg stress tolerance. RESULTS: OsTCTP was ubiquitously expressed in all examined plant tissues, especially in actively dividing and differentiating tissues, such as roots and nodes. OsTCTP was found to localize both the cytosol and the nucleus. OsTCTP was induced by mercuric chloride, cupric sulfate, abscisic acid, and hydrogen peroxide at the protein level in a time-dependent manner. Overexpression of OsTCTP potentiated the activities of several antioxidant enzymes, reduced the Hg-induced H2O2 levels, and promoted Hg tolerance in rice, whereas knockdown of OsTCTP produced opposite effects. And overexpression of OsTCTP did not prevent Hg absorption and accumulation in rice. We also demonstrated that Asn 48 and Asn 97 of OsTCTP amino acids were not the potential N-glycosylation sites. CONCLUSIONS: Our results suggest that OsTCTP is capable of decreasing the Hg-induced reactive oxygen species (ROS), therefore, reducing the damage of ROS and enhancing the tolerance of rice plants to Hg stress. Thus, OsTCTP is a valuable gene for genetic engineering to improve rice performance under Hg contaminated paddy soils.
Assuntos
Adaptação Fisiológica , Mercúrio/toxicidade , Oryza/fisiologia , Proteínas de Plantas/metabolismo , Tumores de Planta/genética , Ácido Abscísico/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/genética , Processamento Alternativo/efeitos dos fármacos , Processamento Alternativo/genética , Antioxidantes/metabolismo , Cobre/toxicidade , Dosagem de Genes , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Glutationa/metabolismo , Peróxido de Hidrogênio/farmacologia , Mutação , Oryza/efeitos dos fármacos , Oryza/genética , Fenótipo , Filogenia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Biossíntese de Proteínas/efeitos dos fármacos , Interferência de RNA/efeitos dos fármacos , Homologia de Sequência de Aminoácidos , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Homologia Estrutural de Proteína , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismoRESUMO
To explore the effects of different concentrations of zinc ï¼Znï¼ on the growth and root architecture classification of maize seedlings under cadmium ï¼Cdï¼ stressï¼ a hydroponic experiment was conducted to study the effects of different concentrations of Zn ï¼0ï¼ 10ï¼ 25ï¼ 50ï¼ 100ï¼ 200ï¼ and 400 µmol·L-1ï¼ on the growthï¼ root architecture and classification characteristicsï¼ Cd contentï¼ root Cd uptake capacityï¼ and photosynthetic system of maize seedlings under Cd stress ï¼50 µmol·L-1ï¼ by using Zhengdan 958 as the experimental material. Principal component analysis and the membership function method were used for comprehensive evaluation. The results showed that the 50 µmol·L-1 Cd stress had a significant toxic effect on maize seedlingsï¼ which significantly reduced chlorophyll content and photosynthetic parameters. The main root lengthï¼ plant heightï¼ biomassï¼ root forksï¼ and root tipsï¼ including the root length and root surface area of the grade â -â ¢ diameter range and the root volume of the grade â -â ¡ diameter rangeï¼ decreased significantlyï¼ which hindered the normal growth and development of maize seedlings. Compared with that under no Zn applicationï¼ 100 µmol·L-1 and 200 µmol·L-1 Zn application reduced the uptake of Cd by maize seedlingsï¼ significantly reduced the Cd content in shoots and roots and the Cd uptake efficiency. The toxic effect on maize seedlings was alleviatedï¼ and the fresh weightï¼ dry weightï¼ tolerance indexï¼ and root forks of shoots and roots were significantly increased. The photosynthesis of maize seedlings was significantly enhancedï¼ and the photosynthetic rate and the total chlorophyll content was significantly increased. The RLï¼ SAï¼ and RV in the â -â ¡ diameter range reached the maximum at 100 µmol·L-1 Znï¼ and the RLï¼ SAï¼ and RV in the â ¢ diameter range reached the maximum at 200 µmol·L-1 Znï¼ which were significantly higher than those without Zn treatment. The comprehensive evaluation of the growth tolerance of maize seedlings showed that 100 µmol·L-1 and 200 µmol·L-1 Zn had better effects on alleviating Cd toxicity. Comprehensive analysis showed that the application of appropriate concentration of Zn could reduce the Cd content in maize seedlingsï¼ the Cd uptake capacityï¼ and Cd uptake efficiency of rootsï¼ increase the biomass accumulation of maize seedlingsï¼ reduce the effect of Cd toxicity on root architectureï¼ reduce the effect on the light and systemï¼ and improve the tolerance of maize seedlings to Cd.
Assuntos
Plântula , Poluentes do Solo , Zinco , Cádmio , Zea mays , Raízes de Plantas , ClorofilaRESUMO
This research aimed to clarify the effects of exogenously applied chitosan on the physiological characteristics, antioxidant activities, and Cd accumulation of wheat (Triticum aestivum L.) seedlings under cadmium (Cd) stress and to identify the key indicators based on the partial least squares model. The wheat variety studied was Bainong207 (BN207), and Cd-stress was achieved by growing seedlings in a hydroponic culture experiment with 10 and 25 µmol·L-1 Cd2+ added to the culture solution. It was found that both Cd-stress at 10 and 25 µmol·L-1 significantly inhibited the chlorophyll content, photosynthesis, and biomass accumulation of wheat seedlings. Seedling roots became shorter and thicker, and the lateral roots decreased under Cd-stress. The Cd-stress also increased H2O2 and MDA accumulation and the degree of cell membrane lipid peroxidation and affected the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). Under Cd stress, exogenous chitosan decreased the Cd content in the aboveground and underground parts of wheat by 13.22 %-21.63 % and 7.92 %-28.32 % and reduced Cd accumulation in the aboveground and underground parts by 5.37 %-6.71 % and 1.91 %-4.09 %, respectively. Whereas exogenous chitosan application significantly reduced the content of H2O2 in roots and aboveground parts of wheat by 38.21 %-47.46 % and 45.81 %-55.73 % and MDA content by 37.65 %-48.12 % and 29.87 %-32.51 %, it increased the activities of SOD and POD in roots by 2.78 %-5.61 % and 13.81 %-18.33 %, respectively. In summary, exogenous chitosan can improve the photosynthetic characteristics and antioxidant enzyme activities of wheat seedlings under Cd stress, reduce the content and accumulation of Cd in the root and aboveground parts of wheat, and alleviate the damage of lipid peroxidation to the cell membrane. All of these results provide the basal data for the application of exogenous chitosan to alleviate Cd toxicity to wheat seedlings.
Assuntos
Antioxidantes , Cádmio , Quitosana , Plântula , Triticum , Triticum/metabolismo , Triticum/efeitos dos fármacos , Triticum/crescimento & desenvolvimento , Cádmio/toxicidade , Cádmio/metabolismo , Quitosana/metabolismo , Quitosana/farmacologia , Plântula/efeitos dos fármacos , Plântula/metabolismo , Antioxidantes/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Poluentes do Solo/toxicidade , Poluentes do Solo/metabolismoRESUMO
This research aimed to clarify the mitigative effect of exogenously applied rare earth element cerium ï¼Ceï¼ on the growthï¼ zinc ï¼Znï¼ accumulationï¼ and physiological characteristics of wheat ï¼Triticum aestivum L.ï¼ seedlings under Zn stress. The wheat variety studied was Bainong307 ï¼BN307ï¼ï¼ and Zn stress was achieved by growing seedlings in a hydroponic culture experiment with 500 µmol·L-1 Zn2 + added to the culture solution. It was found that Zn stress at 500 µmol·L-1 significantly inhibited the chlorophyll contentï¼ photosynthesisï¼ and biomass accumulation of wheat seedlings. Seedling roots became shorter and thickerï¼ and the lateral roots decreased under Zn stress. The Zn stress also increased MDA accumulation and the degree of cell membrane lipid peroxidation and reduced soluble protein contents and the activities of antioxidant enzymes such as superoxide dismutase ï¼SODï¼ï¼ catalase ï¼CATï¼ï¼ and ascorbate peroxidase ï¼APXï¼. On the contraryï¼ exogenous Ce decreased the adsorption and transport of Zn by the root system and alleviated the damage of Zn stress to wheat seedlings. Specificallyï¼ the increase in chlorophyll content ï¼chlorophyll aï¼ chlorophyll bï¼ and total chlorophyllï¼ and photosynthetic parametersï¼ the enhancement of antioxidant enzymes activities and soluble protein levelsï¼ and the reduction in MDA content and the damage of lipid peroxidation to the cell membrane were all driven by exogenous Ceï¼ which ultimately led to the increase in dry matter biomass of the root system and shoot. In summaryï¼ these results provide basic data for the application of exogenous Ce to alleviate Zn toxicity to plants.
Assuntos
Cério , Zinco , Zinco/metabolismo , Antioxidantes/metabolismo , Plântula , Triticum , Cério/metabolismo , Cério/farmacologia , Clorofila A , Superóxido Dismutase/metabolismo , Clorofila , Estresse OxidativoRESUMO
Cadmium (Cd) is a toxic heavy metal to plants and human health. Ascorbate (ASA)-glutathione (GSH) synthesis pathway plays key roles in Cd detoxification, while its molecular regulatory mechanism remains largely unknown, especially in wheat. Here, we found a WRKY transcription factor-TaWRKY74, and its function in wheat Cd stress is not clear in previous studies. The expression levels of TaWRKY74 were significantly induced by Cd stress. Compared to control, the activities of GST, GR, or APX were significantly increased by 1.55-, 1.43-, or 1.75-fold and 1.63-, 2.65-, or 2.30-fold in shoots and roots of transiently TaWRKY74-silenced wheat plants under Cd stress. Similarly, the contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), GSH, or Cd were also significantly increased by 2.39- or 1.25-fold, 1.54- or 1.20-fold, and 1.34- or 5.94-fold in shoots or roots in transiently TaWRKY74-silenced wheat plants, while ASA content was decreased by 47.4 or 43.3% in shoots, 10.7 or 6.5% in roots in these silenced wheat plants, respectively. Moreover, the expression levels of GSH, GPX, GR, DHAR, MDHAR, and APX genes, which are involved in ASA-GSH synthesis, were separately induced by 2.42-, 2.16-, 3.28-, 2.08-, 1.92-, and 2.23-fold in shoots, or by 10.69-, 3.33-, 3.26-, 1.81-, 16.53-, and 3.57-fold in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants, respectively. However, the expression levels of TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1, and TaIRT1 metal transporters genes were decreased by 21.2-76.3% (56.6%, 59.2%, 76.3%, 53.6%, 35.8%, and 21.2%) in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants. Taken together, our results suggested that TaWRKY74 alleviated Cd toxicity in wheat by affecting the expression of ASA-GSH synthesis genes and suppressing the expression of Cd transporter genes, and further affecting Cd uptake and translocation in wheat plants.