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1.
J Agric Food Chem ; 67(42): 11607-11615, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31560536

RESUMO

ζ-carotene desaturase (ZDS) is a key enzyme in carotenoid biosynthesis and plays an important role in plant photosynthesis. We characterized an albino leaf-color mutant obtained from ethyl methanesulfonate treatment: albino and seedling lethality 1 (ale1). The material contains a chloroplast thylakoid defect where photosynthetic pigments declined and reactive oxygen species accumulated resulting in ale1 death within 3 weeks. Positional cloning and sequencing revealed that there was a single base substitution in ALE1, which encoded a ZDS involved in carotenoid biosynthesis. RNAi and complementation tests confirmed the identity of ALE1. Subcellular localization showed that the ALE1 protein is localized in the chloroplast. Expression analysis indicated that the genes involved in chlorophyll and carotenoid biosynthesis were downregulated. We conclude that ALE1 plays an important role in chloroplast and plant growth in rice.


Assuntos
Cloroplastos/enzimologia , Oryza/crescimento & desenvolvimento , Oxirredutases/genética , Proteínas de Plantas/genética , Clorofila/metabolismo , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas , Oryza/enzimologia , Oryza/genética , Oxirredutases/metabolismo , Fotossíntese , Proteínas de Plantas/metabolismo , Interferência de RNA , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento
2.
Plant Mol Biol ; 101(1-2): 183-202, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31286324

RESUMO

KEY MESSAGE: Isoforms of 2-OGDH E1 subunit are not functionally redundant in plant growth and development of A. thaliana. The tricarboxylic acid cycle enzyme 2-oxoglutarate dehydrogenase (2-OGDH) converts 2-oxoglutarate (2-OG) to succinyl-CoA concomitant with the reduction of NAD+. 2-OGDH has an essential role in plant metabolism, being both a limiting step during mitochondrial respiration as well as a key player in carbon-nitrogen interactions. In Arabidopsis thaliana two genes encode for E1 subunit of 2-OGDH but the physiological roles of each isoform remain unknown. Thus, in the present study we isolated Arabidopsis T-DNA insertion knockout mutant lines for each of the genes encoding the E1 subunit of 2-OGDH enzyme. All mutant plants exhibited substantial reduction in both respiration and CO2 assimilation rates. Furthermore, mutant lines exhibited reduced levels of chlorophylls and nitrate, increased levels of sucrose, malate and fumarate and minor changes in total protein and starch levels in leaves. Despite the similar metabolic phenotypes for the two E1 isoforms the reduction in the expression of each gene culminated in different responses in terms of plant growth and seed production indicating distinct roles for each isoform. Collectively, our results demonstrated the importance of the E1 subunit of 2-OGDH in both autotrophic and heterotrophic tissues and suggest that the two E1 isoforms are not functionally redundant in terms of plant growth in A. thaliana.


Assuntos
Arabidopsis/enzimologia , Carbono/metabolismo , Complexo Cetoglutarato Desidrogenase/metabolismo , Nitrogênio/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Complexo Cetoglutarato Desidrogenase/genética , Mitocôndrias/enzimologia , Mutagênese Insercional , Nitratos/metabolismo , Fenótipo , Filogenia , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Isoformas de Proteínas , Subunidades Proteicas , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Sementes/enzimologia , Sementes/genética , Sementes/crescimento & desenvolvimento
3.
Plant Mol Biol ; 101(1-2): 203-220, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31297725

RESUMO

KEY MESSAGE: Here, a functional characterization of a wheat MSR has been presented: this protein makes a contribution to the plant's tolerance of abiotic stress, acting through its catalytic capacity and its modulation of ROS and ABA pathways. The molecular mechanism and function of certain members of the methionine sulfoxide reductase (MSR) gene family have been defined, however, these analyses have not included the wheat equivalents. The wheat MSR gene TaMSRA4.1 is inducible by salinity and drought stress and in this study, we demonstrate that its activity is restricted to the Met-S-SO enantiomer, and its subcellular localization is in the chloroplast. Furthermore, constitutive expression of TaMSRA4.1 enhanced the salinity and drought tolerance of wheat and Arabidopsis thaliana. In these plants constitutively expressing TaMSRA4.1, the accumulation of reactive oxygen species (ROS) was found to be influenced through the modulation of genes encoding proteins involved in ROS signaling, generation and scavenging, while the level of endogenous abscisic acid (ABA), and the sensitivity of stomatal guard cells to exogenous ABA, was increased. A yeast two-hybrid screen, bimolecular fluorescence complementation and co-immunoprecipitation assays demonstrated that heme oxygenase 1 (HO1) interacted with TaMSRA4.1, and that this interaction depended on a TaHO1 C-terminal domain. In plants subjected to salinity or drought stress, TaMSRA4.1 reversed the oxidation of TaHO1, activating ROS and ABA signaling pathways, but not in the absence of HO1. The aforementioned properties advocate TaMSRA4.1 as a candidate for plant genetic enhancement.


Assuntos
Heme Oxigenase-1/metabolismo , Metionina Sulfóxido Redutases/metabolismo , Transdução de Sinais , Estresse Fisiológico , Triticum/enzimologia , Ácido Abscísico/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Arabidopsis/fisiologia , Secas , Perfilação da Expressão Gênica , Heme Oxigenase-1/genética , Metionina Sulfóxido Redutases/genética , Oxirredução , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Salinidade , Tolerância ao Sal , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Triticum/genética , Triticum/fisiologia , Técnicas do Sistema de Duplo-Híbrido
4.
Plant Physiol Biochem ; 141: 456-465, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31247428

RESUMO

Alfalfa (Medicago sativa L.) is an important perennial legume and used as a forage crop worldwide, and has extensive resistance to various abiotic stresses. Nitric oxide (NO) plays a critical role in response to external and internal cues to regulate plant growth and development. However, endogenous NO-mediated molecular mechanisms of drought tolerance in alfalfa is poorly understood. To get a deeper insight into the regulate pathway of NO, RNA-Seq was used to profile transcriptome changes of alfalfa seedlings, which were treated with NO scavenger under normal and drought conditions. A total of 1,025 and 3,461 differently-expressed genes (FDR < 0.0001; fold change ≥ 2) were observed while NO absence under normal and drought conditions, respectively. Based on GO enrich and KEGG pathway analysis, we found NO absence induced photosynthesis, carbon fixation in photosynthetic organisms and primary metabolism were significantly up-enriched. Most oxidoreductase, dehydrogenase, reductase and transferase genes were down-regulated in the above processes. Moreover, NO absence restrained chlorophyll biosynthesis and decreased different sugar content. Therefore, this work provides insights into the mechanism that NO-mediated enhanced photosynthesis and carbohydrate metabolism in alfalfa under drought stress.


Assuntos
Metabolismo dos Carboidratos , Secas , Medicago sativa/enzimologia , Medicago sativa/fisiologia , Óxido Nítrico/química , Fotossíntese , Parede Celular/metabolismo , Clorofila/química , Cloroplastos/metabolismo , Perfilação da Expressão Gênica , Biblioteca Gênica , Plântula/enzimologia , Plântula/fisiologia , Análise de Sequência de RNA , Amido/química , Estresse Fisiológico , Sacarose/química
5.
Ecotoxicol Environ Saf ; 181: 491-498, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31229839

RESUMO

Indian mustard (Brassica juncea L.) was more tolerance to Cs than some sensitive plants, such as Arabidopsis thaliana and Vicia faba, and may have a special detoxification mechanism. In this study, the effects on reactive oxygen species (ROS) content, the antioxidant enzyme system and chelation system in Indian mustard were studied by observing different plant physiological responses. In addition, we focused on the analysis of gene regulatory networks related to ROS formation, ROS scavenging system, and other stress-response genes to Cs exposure using a transcriptome-sequencing database. The results showed that ROS and malonaldehyde content in seedlings increased significantly in Cs-treatment groups. The enzyme activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were increased, and the synthesis of antioxidants glutathione, phytochelatin and metallothionein also increased under Cs treatment. Further analysis showed that ROS formation pathways were primarily the photosynthetic electron transport chain process and photorespiration process in the peroxisome. Antioxidant enzyme systems and the respiratory burst oxidase homolog protein-mediated signal transduction pathway played a key role in ROS scavenging. In summary, one of the mechanisms of tolerance and detoxification of Indian mustard to Cs was that it enhanced the scavenging ability of antioxidant enzymes to ROS, chelated free Cs ions in cells and regulated the expression of related disease-resistant genes.


Assuntos
Antioxidantes/metabolismo , Césio/metabolismo , Mostardeira/fisiologia , Poluentes do Solo/metabolismo , Estresse Fisiológico/genética , Redes Reguladoras de Genes , Mostardeira/enzimologia , Mostardeira/genética , Mostardeira/metabolismo , Oxirredução , Fitoquelatinas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Plântula/enzimologia , Plântula/metabolismo
6.
Ecotoxicol Environ Saf ; 181: 49-59, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31170649

RESUMO

N-acetylcysteine (N-Acetyl L-cysteine, NAC) is a thiol compound derived from the addition of the acetyl group to cysteine amino acid. NAC has been used as an antioxidant, free radical scavenger, and chelating agent for reducing the deleterious effects on plants of biotic and abiotic environmental stresses. It can also relieve heavy metal (HM) toxicity, although its alleviating mechanism remains unknown. In this study, we compared HM-stressed (Cu, Hg, Cd and Pb, 100 µM each) wheat seedlings without NAC treatment and in combination with NAC (1 mM). In comparison to HMs alone, NAC treatment in combination with HMs (Cu, Cd, Hg and Pb, respectively) stimulated root growth (1.1-, 1.5-, 10.5- and 1.9-fold), and significantly increased fresh (1.3-, 1.5-, 4.3- and 1.4-fold) and dry (1.2-, 1.5-, 2.5- and 1.2-fold) mass. Combination treatment also led to significant reductions in HM concentrations (1.3-, 1.4-, 4- and 1.1-fold, respectively). GSH (1.1 - 1.8-fold), TBARS (1.4 - 2.7-fold) and H2O2 (1.6 - 1.8-fold) contents in treatment with HMs alone were significantly mitigated by the NAC combination. Some of the antioxidant enzyme activities increased or reduced by some HM treatments alone were stimulated by a combination of NAC with HMs, or remained unchanged or changed only insignificantly, supported by the phenolic pool of the plant. Ferulic, p-comaric and syringic acids were the major phenolic acids (PAs) in the roots in free, ester, glycoside and ester-bound forms, and their concentrations were increased by HM treatments alone, in comparison to the control seedlings, while PAs concentrations were relatively reduced by NAC in combination with HMs. These results indicate that NAC can alleviate HM toxicity and improve the growth of HM-stressed wheat seedlings by coordinated induction of the phenolic pool and the antioxidant defence system.


Assuntos
Acetilcisteína/farmacologia , Antioxidantes/farmacologia , Metais Pesados/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Triticum/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Hidroxibenzoatos/metabolismo , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/crescimento & desenvolvimento , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Triticum/enzimologia , Triticum/crescimento & desenvolvimento
7.
Ecotoxicol Environ Saf ; 181: 345-352, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31202935

RESUMO

Nanomaterials are being used increasingly in various areas such as electronic devices manufacture, medicine, mechanical devices production, and even food industry. Therefore, the evaluation of their toxicity is mandatory. Graphene oxide (GO) has been shown to have both positive as well as negative impact on different crop plants, depending on species, dose, and duration of exposure. The current study evaluated the impact of GO sheets at different concentrations (500, 1000 and 2000 mg/L) on physiological, biochemical and genetic levels to determine the possible toxic action. Wheat caryopses were treated with GO for 48 h and 7 days. The germination rate and roots elongation decreased in a dose-response manner, except the sample treated with GO at a concentration of 1000 mg/L. Mitotic index has ascendant trend; its increase may be due to the accumulation of prophases GO induced significant accumulation of the cells with aberrations, their presence suggests a clastogenic/aneugenic effect of these carbon nanomaterials. Regarding enzymatic and non-enzymatic antioxidant system defence, the activity varied depending on the dose of GO. Thus, chlorophyll a pigments content decreased significantly at high dose (2000 mg/L), while the carotenoid pigments had lower content at 500 mg/L of GO, and no statistical difference encountered in case of chlorophyll b amount. The antioxidant enzyme activity (CAT, POD, and SOD) was higher at low dose of GO, indicating the presence of oxidative stress generated as a response to the GO treatment. Also, the free radical scavenging activity of the polyphenolic compounds was enhanced upon GO exposure. The GO accumulation has been identified by transmission electron microscopy only at plumules level, near the intercellular space.


Assuntos
Grafite/toxicidade , Nanoestruturas/toxicidade , Triticum/efeitos dos fármacos , Antioxidantes/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Germinação/efeitos dos fármacos , Estresse Oxidativo , Óxidos/toxicidade , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/metabolismo , Triticum/enzimologia , Triticum/crescimento & desenvolvimento , Triticum/metabolismo
8.
Environ Pollut ; 251: 45-55, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31071632

RESUMO

Hydrogen gas (H2) has been shown as an important factor in plant tolerance to abiotic stresses, but the underlying mechanisms remain unclear. In the present study, the effects of H2 and its interaction with nitric oxide (NO) on alleviating cadmium (Cd) stress in Brassica campestris seedlings were investigated. NO donor (SNP) or hydrogen-rich water (HRW) treatment showed a significant improvement in growth of Cd-stressed seedlings. Cd treatment upregulated both endogenous NO and H2 (36% and 66%, respectively), and the increase of H2 was prior to NO increase. When treated with NO scavenger (PTIO) or NO biosynthesis enzyme inhibitors (L-NAME and Gln), HRW-induced alleviation under Cd stress was prevented. Under Cd stress, HRW pretreatment significantly enhanced the NO accumulation, and together up-regulated the activity of NR (nitrate reductase) and expression of NR. HRW induced lower reactive oxygen species (ROS), higher AsA content, enhanced activity of POD (peroxidase) and SOD (superoxide dismutase) in seedling roots were inhibited by PTIO, L-NAME and Gln. Through proteomic analysis, the level of 29 proteins were changed in response to H2 and NO-induced amelioration of Cd stress. Nearly half of them were involved in oxidation-reduction processes (about 20%) or antioxidant enzymes (approximately 20%). These results strongly indicate that in Cd-stressed seedlings, pretreatment with HRW induces the accumulation of H2 (biosynthesized or permeated), which further stimulates the biosynthesis of NO through the NR pathway. Finally, H2 and NO together enhance the antioxidant capabilities of seedlings in response to Cd toxicity.


Assuntos
Antioxidantes/metabolismo , Brassica/efeitos dos fármacos , Cádmio/toxicidade , Hidrogênio/farmacologia , Óxido Nítrico/biossíntese , Poluentes do Solo/toxicidade , Brassica/enzimologia , Brassica/metabolismo , Cádmio/metabolismo , Doadores de Óxido Nítrico/farmacologia , Oxirredução , Proteômica , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/metabolismo , Poluentes do Solo/metabolismo , Regulação para Cima/efeitos dos fármacos
9.
Environ Sci Pollut Res Int ; 26(20): 20208-20218, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31098903

RESUMO

Cyanate (CNO-) has been produced in the environment through either natural or anthropogenic sources. However, due to industrialization, it has been led more over-loads. In this study, interaction of CNO- uptake by rice seedlings with nitrate assimilation was investigated using gene expression analysis after an acute phytotoxicity assay. Our results showed that CNO- exposure caused inhibition on relative growth rates of plants. CNO- analysis demonstrated that rice seedlings had higher potential for CNO- uptake and the removal rates showed a zero-order kinetic. PCR analysis exposed that OsCYN transcript was not significantly induced by CNO- treatments in rice tissues and CNO- exposure also repressed gene expression of the collaborative enzyme carbonic anhydrase (CA), suggesting that assimilation of CNO- initiated by the enzyme cyanase (CYN) in rice seedlings was an enzyme-limitation reaction. Gene expression of other enzymes involved in nitrate metabolism was tissue-specific under CNO- exposure, suggesting that rice seedlings were able to trigger its intrinsic regulative and responsive mechanisms to cope up with uneven N conditions. Significant upregulation of three OsGDH isogenes, except for OsGDH1 in roots, was detected in both rice materials with enhancing CNO- concentrations, suggesting that GDH may play a primary role to maintain the balance of C and N in plants under CNO- exposure. In conclusion, because the innate pool of CYN activity was non-sufficient to degrade exogenous CNO- by rice seedlings, CNO-derived ammonium only can serve as a supporting N source to support growth of rice seedling under non-effective doses of CNO- exposure.


Assuntos
Carbono-Nitrogênio Liases/genética , Cianatos/metabolismo , Expressão Gênica/efeitos dos fármacos , Nitratos/metabolismo , Oryza/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Transporte Biológico , Cianatos/farmacologia , Oryza/enzimologia , Oryza/genética , Plântula/enzimologia , Plântula/genética
10.
Plant Sci ; 280: 321-329, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30824011

RESUMO

Cysteine functions not only as an amino acid in proteins but also as a precursor for a large number of essential biomolecules. Cysteine is synthesized via the incorporation of sulfide to O-acetylserine under the catalysis of O-acetylserine(thiol)lyase (OASTL). In dicotyledonous Arabidopsis, nine OASTL genes have been reported. However, in their null mutants, only the mutant of CS26 encoding S-sulfocysteine synthase showed the visible phenotypic changes, displaying significantly small plants and pale-green leaves under long-day condition but not short-day condition. Up to now, no OASTL gene or mutant has been identified in monocotyledon. In this study, we isolated a green-revertible albino mutant gra78 in rice (Oryza sativa). Its albino phenotype at the early seedling stage was sensitive to temperature but independent of photoperiod. Map-based cloning revealed that candidate gene LOC_Os01g59920 of GRA78 encodes a putative S-sulfocysteine synthase showing significant similarity with Arabidopsis CS26. Complementation experiment confirmed that mutation in LOC_Os01g59920 accounted for the mutant phenotype of gra78. GRA78 is constitutively expressed in all tissues and its encoded protein is targeted to the chloroplast. In addition, qRT-PCR suggested that expression levels of four OASTL homolog genes and five photosynthetic genes were remarkably down-regulated.


Assuntos
Liases/metabolismo , Oryza/enzimologia , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Liases/genética , Liases/ultraestrutura , Mutação , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/ultraestrutura , Fenótipo , Fotossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/ultraestrutura
11.
Plant Physiol Biochem ; 139: 197-206, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30908971

RESUMO

Proteases play a main role in the mobilization of storage proteins during seed germination. Until today, there is little information about the involvement of serine proteases, particularly subtilases, in the germination of barley grains. The aims of the present work were to study the contribution of serine proteases to the total proteolytic activity induced during germination of barley grains and evaluate the specific involvement of subtilases in this process. Proteolytic activity assayed against azocasein in the presence of specific inhibitors, showed that serine proteases contributed between 10 and 20% of total activity along germination. Subtilase activity increased from day 1 after imbibition with a peak between days 4-5. Moreover, in vivo determination of subtilase activity in germinating grains revealed increasing activity along germination mainly localized in the seed endosperm and developing rootlets. Finally, the expression of 19 barley genes encoding subtilases was measured by real time PCR during germination. Three of the analyzed genes increased their expression along germination, five showed a transient induction, one was down-regulated, nine remained unchanged and one was not expressed. The present work demonstrates the involvement of subtilases in germination of barley grains and describes the positive association of eight subtilase genes to this process.


Assuntos
Germinação , Hordeum/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Plântula/crescimento & desenvolvimento , Subtilisinas/metabolismo , Aminoácidos/metabolismo , Regulação da Expressão Gênica de Plantas , Hordeum/enzimologia , Hordeum/metabolismo , Proteólise , Reação em Cadeia da Polimerase em Tempo Real , Plântula/enzimologia , Plântula/metabolismo
12.
Molecules ; 24(3)2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30717241

RESUMO

Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) and ethylamine mainly in roots, and that theanine accumulation depends on the availability of ethylamine which is derived from alanine (Ala) decarboxylation catalyzed by alanine decarboxylase (AlaDC). However, the specific gene encoding AlaDC protein remains to be discovered in tea plants or in other species. To explore the gene of AlaDC in tea plants, the differences in theanine contents and gene expressions between pretreatment and posttreatment of long-time nitrogen starvation were analyzed in young roots of two tea cultivars. A novel gene annotated as serine decarboxylase (SDC) was noted for its expression levels, which showed high consistency with theanine content, and the expression was remarkably high in young roots under sufficient nitrogen condition. To verify its function, full-length complementary DNA (cDNA) of this candidate gene was cloned from young roots of tea seedlings, and the target protein was expressed and purified from Escherichia coli (E. coli). The enzymatic activity of the protein for Ala and Ser was measured in vitro using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). The results illustrated that the target protein could catalyze the decarboxylation of Ala despite of its high similarity with SDC from other species. Therefore, this novel gene was identified as AlaDC and named CsAlaDC. Furthermore, the gene expression levels of CsAlaDC in different tissues of tea plants were also quantified with quantitative real-time PCR (qRT-PCR). The results suggest that transcription levels of CsAlaDC in root tissues are significantly higher than those in leaf tissues. That may explain why theanine biosynthesis preferentially occurs in the roots of tea plants. The expression of the gene was upregulated when nitrogen was present, suggesting that theanine biosynthesis is regulated by nitrogen supply and closely related to nitrogen metabolism for C. sinensis. The results of this study are significant supplements to the theanine biosynthetic pathway and provide evidence for the differential accumulation of theanine between C. sinensis and other species.


Assuntos
Alanina/metabolismo , Camellia sinensis/genética , Carboxiliases/genética , Regulação da Expressão Gênica de Plantas , Glutamatos/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/genética , Camellia sinensis/enzimologia , Carboxiliases/metabolismo , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Etilaminas/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Nitrogênio/deficiência , Nitrogênio/farmacologia , Especificidade de Órgãos , Filogenia , Folhas de Planta/enzimologia , Folhas de Planta/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/enzimologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Plântula/enzimologia , Plântula/genética , Serina/metabolismo , Chá
13.
Plant Biol (Stuttg) ; 21(4): 634-642, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30664832

RESUMO

Pogonatherum crinitum is a promising lead (Pb) hyperaccumulator due to its high Pb tolerance and accumulation ability. However, the mechanisms that support Pb accumulation and tolerance in P. crinitum are not yet clearly understood. An indoor hydroponic experiment was conducted by cultivating P. crinitum seedlings exposed to intermittent Pb stress for 60 days, divided into four stages (T1, T2, T3 and T4), with a 15-day duration per stage. The following concentrations of Pb were used: 0, 500, 0, 500 mg·l-1 and 0, 1000, 0, 1000 mg·l-1 ). Antioxidant enzyme activity, Pb concentration and subcellular distribution of Pb were measured at each of the above stages. The results showed that superoxide dismutase (SOD) activity in shoots, and SOD, peroxidase (POD) and malondialdehyde (MDA) activity in shoots and roots significantly increased from T1 (no Pb stress) to T2 (Pb stress) in both 500 mg·l-1 and 1000 mg·l-1 treatments; however, no significant difference was noted between stages T3 (no Pb stress) and T4 (Pb stress). There was no obvious effect of Pb stress on catalase (CAT) activity in shoots and roots among different stages. The Pb concentration in shoots was up to 5090.90 mg·kg-1 and 7573.57 mg·kg-1 , and the bioconcentration factor (BFC) was 10.18 and 7.57 for the 500 mg·l-1 and 1000 mg·l-1 treatments, respectively, which confirmed the Pb hyperaccumulator characteristics of P. crinitum. For plants under Pb stress, most of the Pb was fixed in the cell walls, with a smaller amount in leaves and root vacuoles. Both SOD and POD scavenging of reactive oxygen radicals and fixing and compartmentalisation of Pb in the cell wall might play important roles in detoxification of P. crinitum seedlings in response to Pb stress. There was no phased response of P. crinitum to intermittent Pb stress and the physiological response to Pb stress may be contiguous.


Assuntos
Catalase/efeitos dos fármacos , Chumbo/metabolismo , Peroxidase/efeitos dos fármacos , Proteínas de Plantas/efeitos dos fármacos , Poaceae/efeitos dos fármacos , Plântula/efeitos dos fármacos , Superóxido Dismutase/efeitos dos fármacos , Catalase/metabolismo , Relação Dose-Resposta a Droga , Chumbo/toxicidade , Malondialdeído/metabolismo , Peroxidase/metabolismo , Proteínas de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Poaceae/enzimologia , Poaceae/crescimento & desenvolvimento , Poaceae/metabolismo , Plântula/enzimologia , Plântula/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Frações Subcelulares/metabolismo , Superóxido Dismutase/metabolismo
14.
Artigo em Inglês | MEDLINE | ID: mdl-30596331

RESUMO

The roles of enzymatic reactions and redox reactions caused by reactive oxygen species (ROS) in formaldehyde metabolism in tomatoes and wheat seedlings and the changes in peroxidase (POD) and catalase (CAT) activities in plants were investigated. Differences in the breakdown of added formaldehyde between fresh and boiled plant extracts were determined to calculate the contributions of different removal mechanisms. Two plant seedlings efficiently removed formaldehyde from air when its level varied from 0.65 to 1.91 mg m-3; meanwhile, the maximum rate at which tomato seedlings transported formaldehyde from air to the rhizosphere solution reached 182.26 µg h-1 kg-1 FW (fresh weight). Metabolism in plants was mainly responsible for the formaldehyde dissipation. The enzymatic contribution to formaldehyde dissipation decreased with increasing shoot exposure time or air formaldehyde level, while the redox contribution increased in importance because of an increasing level of ROS. The different enzymatic antioxidant activities of plants resulted in different levels of ROS and hence different tolerance and removal efficiencies toward formaldehyde. The self-enhancing ability of plants to remove formaldehyde via redox reactions suggested that the formaldehyde removal efficiency could be enhanced by plant adaptation to environmental stress.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/prevenção & controle , Antioxidantes/metabolismo , Formaldeído/análise , Espécies Reativas de Oxigênio/metabolismo , Plântula/enzimologia , Catalase/metabolismo , Lycopersicon esculentum/enzimologia , Lycopersicon esculentum/crescimento & desenvolvimento , Oxirredução , Peroxidases/metabolismo , Plântula/crescimento & desenvolvimento , Estresse Fisiológico , Triticum/enzimologia , Triticum/crescimento & desenvolvimento
15.
J Plant Physiol ; 232: 65-73, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30537614

RESUMO

Protective compounds such as non-enzymatic antioxidants, osmolytes and signal molecules have been applied to plants exposed to various environmental stresses to increase their stress tolerance. However, there are not enough records about the response of plants to alpha lipoic acid (ALA) application with antioxidant properties. Therefore, this study was designed to evaluate the function of exogenous ALA on the photosynthetic performance of maize seedlings grown in hydroponic conditions under drought stress. Three weeks old seedlings were treated with or without ALA (12 µM) and they were subjected to drought stress induced by 10% polyethylene glycol (PEG6000) for 24 h. Chlorophyll content, gas exchange parameters, chlorophyll fluorescence and the expression levels of genes involved in CO2 fixation (ribulose-1,5-bisphosphate carboxylase (rubisco), phosphoenolpyruvate carboxylase (PEPc), Rubisco activase (RCA)) and chlorophyll metabolism (magnesium chelatase (Mg-CHLI) and chlorophyllase (Chlase)) were determined. The application of ALA increased chlorophyll content and the activity of photosystem II in comparison to the untreated seedlings under drought stress. The relative expression levels of Rubisco, PEPc, RCA and Mg-CHLI significantly increased while the Chlase gene expression decreased in seedlings to which ALA was applied in comparison those to which it was not applied under the stress. These results suggest that exogenous ALA can enhance the photosynthetic performance of maize seedlings exposed to drought by inducing photosystem II activity and the gene expressions of carbon fixation and chlorophyll metabolism enzymes.


Assuntos
Ciclo do Carbono/efeitos dos fármacos , Clorofila/metabolismo , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Plântula/efeitos dos fármacos , Ácido Tióctico/farmacologia , Zea mays/efeitos dos fármacos , Western Blotting , Desidratação , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Plântula/enzimologia , Plântula/metabolismo , Zea mays/enzimologia , Zea mays/metabolismo
16.
Int J Biol Macromol ; 125: 361-369, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30528996

RESUMO

Oat (Avena sativa L.) seedling extract exhibited a high degree of catalytic activities. Bioinformatics were used to identify ß-amylases as abundant enzymes in the oat seedling extract. These identified oat enzymes are a member of the GH14 family. Proteins in the Avena sativa seedling extract were separated by SDS-PAGE and 2 major protein bands with an apparent molecular weights of 53 and 42 kDa were the subject of this study. These materials were digested with trypsin and the amino acid sequences of the tryptic peptides were determined by LC/ESI/MS/MS and database searches. These sequences were used to identify cDNAs from expressed sequence tags (EST) and Transcriptome Shotgun Assembly (TSA) of Avena sativa. Based upon EST and TSA sequences, at least 6 predicted different sequences were identified and assigned as ß-amylases. Insights into structural characterization of the oat predicted ß-amylases were analyzed using in silico approaches. The identified ß-amylases conserved the two Glu residues assigned as the "putative" catalytic residues, which would act as an acid and base pair in the catalytic process. A similar core (ß/α)8-barrel architecture was found in the predicted oat ß-amylases with a specific location of the active site in a pocket-like cavity structure made at one end of this core (ß/α)8-barrel domain. This suggests an accessibility of the non-reducing end of the substrate towards the oat ß-amylases and thus confirming that are exo-acting hydrolases. The results provide a detailed view of the main residues involved in catalysis in this kind of enzyme.


Assuntos
Avena/química , Extratos Vegetais/química , Plântula/química , beta-Amilase/química , Sequência de Aminoácidos , Avena/enzimologia , Biologia Computacional/métodos , Extração Líquido-Líquido , Modelos Moleculares , Filogenia , Conformação Proteica , Plântula/enzimologia , Solubilidade , Relação Estrutura-Atividade , beta-Amilase/classificação , beta-Amilase/isolamento & purificação
17.
Plant Sci ; 276: 220-228, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30348322

RESUMO

The U-Box E3 ubiquitin ligase, AtPUB46, functions in the drought response: T-DNA insertion mutants of this single paralogous gene are hypersensitive to water- and oxidative stress (Adler et al. BMC Plant Biology 17:8, 2017). Here we analyze the phenotype of AtPUB46 overexpressing (OE) plants. AtPUB46-OE show increased tolerance to water stress and have smaller leaf blades and reduced stomatal pore area and stomatal index compared with wild type (WT). Despite this, the rate of water loss from detached rosettes is similar in AtPUB46-OE and WT plants. Germination of AtPUB46-OE seeds was less sensitive to salt than WT whereas seedling greening was more sensitive. We observed a complex response to oxidative stress applied by different agents: AtPUB46-OE plants were hypersensitive to H2O2 but hyposensitive to methyl viologen. AtPUB46-GFP fusion protein is cytoplasmic, however, in response to H2O2 a considerable proportion translocates to the nucleus. We conclude that the differential stress phenotype of the AtPUB46-OE does not result from its smaller leaf size but from a change in the activity of a stress pathway(s) regulated by a degradation substrate of the AtPUB46 E3 and also from a reduction in stomatal pore size and index.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Peróxido de Hidrogênio/farmacologia , Ubiquitina-Proteína Ligases/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Citoplasma/enzimologia , Desidratação , Secas , Genes Reporter , Germinação , Estresse Oxidativo , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Estômatos de Plantas/enzimologia , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Proteínas Recombinantes de Fusão , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Sementes/enzimologia , Sementes/genética , Sementes/fisiologia , Cloreto de Sódio/metabolismo , Estresse Fisiológico , Ubiquitina-Proteína Ligases/genética
18.
Planta ; 248(4): 1017-1027, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30027414

RESUMO

MAIN CONCLUSIONS: ALDH7B4 expression contributes to abiotic stress tolerance. The NAC transcription factor ATAF1 is a main regulator of expression of the ALDH7B4 gene in Arabidopsis thaliana as shown by ATAF1 mutants. The aldehyde dehydrogenase 7B4 (ALDH7B4) protein has important roles in detoxification of excessive aldehydes, elimination of reactive oxygen species (ROS) and inhibition of lipid peroxidation when plants are exposed to abiotic stress. However, the regulation of the expression of the ALDH7B4 gene under stress is largely unknown. Promoter studies revealed crucial cis-elements in the ALDH7B4 promoter in response to heat and stress combinations. Using a yeast one-hybrid assay, several NAC transcription factors, including ATAF1 were isolated. These transcription factors play an important role in plant adaptation to abiotic stress. ATAF1 activates the expression of the ALDH7B4 gene by directly binding to the promoter. Overexpression of ATAF1 in Arabidopsis plants results in elevated expression of ALDH7B4 in seeds, seedlings, and mature plants, whereas ATAF1 knock-out mutant plants abolished the expression of ALDH7B4. This study implies that ATAF1 may confer stress tolerance by up-regulating the target gene ALDH7B4.


Assuntos
Aldeído Desidrogenase/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Regulação da Expressão Gênica de Plantas , Proteínas Repressoras/metabolismo , Adaptação Fisiológica , Aldeído Desidrogenase/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Expressão Gênica , Técnicas de Inativação de Genes , Temperatura Alta , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Proteínas Repressoras/genética , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Sementes/enzimologia , Sementes/genética , Sementes/fisiologia , Estresse Fisiológico , Técnicas do Sistema de Duplo-Híbrido , Regulação para Cima
19.
Biosci Biotechnol Biochem ; 82(10): 1790-1802, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29972345

RESUMO

Rutin, a 3-rutinosyl quercetin, is a representative flavonoid distributed in many plant species, and is highlighted for its therapeutic potential. In this study, we purified uridine diphosphate-rhamnose: quercetin 3-O-glucoside 6″-O-rhamnosyltransferase and isolated the corresponding cDNA (FeF3G6″RhaT) from seedlings of common buckwheat (Fagopyrum esculentum). The recombinant FeF3G6″RhaT enzyme expressed in Escherichia coli exhibited 6″-O-rhamnosylation activity against flavonol 3-O-glucoside and flavonol 3-O-galactoside as substrates, but showed only faint activity against flavonoid 7-O-glucosides. Tobacco cells expressing FeF3G6″RhaT converted the administered quercetin into rutin, suggesting that FeF3G6″RhaT can function as a rhamnosyltransferase in planta. Quantitative PCR analysis on several organs of common buckwheat revealed that accumulation of FeF3G6″RhaT began during the early developmental stages of rutin-accumulating organs, such as flowers, leaves, and cotyledons. These results suggest that FeF3G6″RhaT is involved in rutin biosynthesis in common buckwheat.


Assuntos
Fagopyrum/metabolismo , Hexosiltransferases/metabolismo , Rutina/biossíntese , Cromatografia Líquida de Alta Pressão , Clonagem Molecular , Eletroforese em Gel de Poliacrilamida , Fagopyrum/enzimologia , Hexosiltransferases/genética , Hexosiltransferases/isolamento & purificação , Fenóis/metabolismo , Reação em Cadeia da Polimerase , Plântula/enzimologia , Análise de Sequência de RNA , Especificidade por Substrato
20.
J Basic Microbiol ; 58(8): 686-697, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29901825

RESUMO

The induced resistance against plant pathogens via biocontrol agents is considered as an eco-friendly and promising strategy. In this study, the induced resistance against Magnaporthe oryzae (M. oryzae) in rice seedling by a new potential biocontrol agent Streptomyces JD211 (JD211) was evaluated. The effects of JD211 on defense-related enzymes activities and defense genes expression were investigated. The biocontrol efficacy of different JD211 concentrations was different, and the treatment of 10 g kg-1 JD211 achieved the highest biocontrol efficacy. Activities of catalase, phenylalanine ammonia-lyase (PAL) and ß-1,3-glucanase significantly increased in the presence of JD211. The gene expression level of both PAL and pathogenesis related protein 1 increased when rice seedlings were inoculated with JD211 alone or co-inoculated with M. oryzae, and the expression level of chitinase gene was enhanced by JD211 in the later stage. All results suggested that JD211 could increase the rice resistance by stimulating a series of defense responses, which was the result of induced systemic resistance by JD211. This work will provide a new biocontrol agent against Magnaporthe oryzae in rice seedling.


Assuntos
Agentes de Controle Biológico , Resistência à Doença/fisiologia , Magnaporthe/fisiologia , Oryza/microbiologia , Doenças das Plantas/prevenção & controle , Plântula/microbiologia , Streptomyces/fisiologia , Antibiose , Catalase/genética , Catalase/metabolismo , Quitinases/genética , Resistência à Doença/genética , Fungicidas Industriais , Regulação da Expressão Gênica de Plantas , Glucana 1,3-beta-Glucosidase , Oryza/fisiologia , Fenilalanina Amônia-Liase/genética , Fenilalanina Amônia-Liase/metabolismo , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia
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