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1.
Science ; 371(6526): 276-280, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33446554

RESUMO

Soil compaction represents a major challenge for modern agriculture. Compaction is intuitively thought to reduce root growth by limiting the ability of roots to penetrate harder soils. We report that root growth in compacted soil is instead actively suppressed by the volatile hormone ethylene. We found that mutant Arabidopsis and rice roots that were insensitive to ethylene penetrated compacted soil more effectively than did wild-type roots. Our results indicate that soil compaction lowers gas diffusion through a reduction in air-filled pores, thereby causing ethylene to accumulate in root tissues and trigger hormone responses that restrict growth. We propose that ethylene acts as an early warning signal for roots to avoid compacted soils, which would be relevant to research into the breeding of crops resilient to soil compaction.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Etilenos/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Solo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Raízes de Plantas/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo
2.
Food Chem ; 339: 128151, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33152896

RESUMO

The effects of aloe vera (Aloe vera (L.) Burm. f.) gel treatment on the incidence of superficial scald in 'Starking' apples (Malus domestica Borkh. Var. Starking) during cold storage were studied. Apples were harvested at the pre-climacteric stage and treated with aloe vera gel. The treatment increased malondialdehyde content and membrane lipid damage. Furthermore, it inhibited the release of ethylene at the early stage but increased it in the later stage. The expression level of ACC synthase 1 (MdACS1) also increased, and the antioxidant capacity in apples, particularly, catalase, peroxidase, and superoxide dismutase activities, all decreased, while concomitantly, the content of α-farnesene and its oxidation product, conjugated triene increased, thereby aggravating superficial scald incidence during storage at low temperature.


Assuntos
Conservação de Alimentos/métodos , Malus/fisiologia , Preparações de Plantas , Antioxidantes/metabolismo , Temperatura Baixa , Ciclopropanos/farmacologia , Enzimas/metabolismo , Etilenos/metabolismo , Armazenamento de Alimentos , Frutas/fisiologia , Malus/efeitos dos fármacos , Oxirredução , Preparações de Plantas/farmacologia , Proteínas de Plantas/metabolismo , Sesquiterpenos/metabolismo
3.
Food Chem ; 339: 127981, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32916399

RESUMO

The objective of the present study was to explore the effect of folic acid on the postharvest physiology of broccoli placed in storage. Broccoli heads were immersed in 5 mg L-1 folic acid for 10 min, then stored at 20 ± 1 °C for 4 days. Results indicated that the postharvest treatment of broccoli with folic acid decreased the rate of flower opening and yellowing, inhibited weight loss, reduced the level of respiration, as well as ethylene generation. Folic acid-treated broccoli maintained their level of chlorophyll, total soluble solids, vitamin C, total phenolics, flavonoids, glucosinolate, and folic acid. Treated broccoli also exhibited reduced accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS). Concomitantly, antioxidant enzyme activity and corresponding gene expression were also enhanced. In contrast, chlorophyll-degrading enzyme gene expression was suppressed. These results indicated that folic acid treatment of broccoli could be used to prolong shelf-life.


Assuntos
Brassica/efeitos dos fármacos , Ácido Fólico/farmacologia , Armazenamento de Alimentos/métodos , Antioxidantes/metabolismo , Ácido Ascórbico/análise , Brassica/fisiologia , Catalase/genética , Catalase/metabolismo , Etilenos/metabolismo , Flavonoides/análise , Ácido Fólico/química , Expressão Gênica/efeitos dos fármacos , Malondialdeído/metabolismo , Peroxidases/genética , Peroxidases/metabolismo , Fenóis/análise , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Temperatura
4.
Food Chem ; 338: 128005, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32977138

RESUMO

Peach (Prunus persica L.) fruit are highly susceptible to chilling injury during cold storage, resulting in internal flesh browning and a failure to soften normally. We have examined the effect of a postharvest treatment consisting of a brief (30 s) dip in the natural plant hormone jasmonic acid, prior to storage at 4 °C. Jasmonic acid treatment reduced the severity of internal flesh browning and did not inhibit fruit softening over a 35 d storage period. Two major physiological effects of jasmonic acid on the fruit were observed, an increase in ethylene production and a prevention of the decline in soluble sugar content seen in controls. An increased soluble sugar content may have multiple benefits in resisting chilling stress, scavenging reactive oxygen species and acting to stabilize membranes. Our results show that a treatment with jasmonic acid can enhance chilling tolerance of peach fruit by regulating ethylene and sugar metabolism.


Assuntos
Ciclopentanos/farmacologia , Etilenos/metabolismo , Frutas/efeitos dos fármacos , Oxilipinas/farmacologia , Prunus persica/efeitos dos fármacos , Prunus persica/metabolismo , Açúcares/metabolismo , Temperatura Baixa , Armazenamento de Alimentos/métodos , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Reguladores de Crescimento de Planta/farmacologia , Proteínas de Plantas/genética , Prunus persica/genética
5.
Food Chem ; 334: 127479, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32688181

RESUMO

Calcium treatment effects on malate metabolism and the GABA pathway in 'Cripps Pink' apple fruit during storage were investigated. Postharvest apple fruit treated with 1% and 4% calcium chloride solutions were stored at 25 ± 1 °C. The 4% calcium treatment suppressed declines in titratable acidity and malate content and increased succinate and oxalate concentrations. Calcium treatment also reduced the respiration rate and decreased ethylene production peak during storage. Moreover, 4% calcium treatment significantly enhanced cyNAD-MDH and PEPC activities and upregulated MdMDH1, MdMDH2, MdPEPC1 and MdPEPC2 expression while inhibiting cyNADP-ME and PEPCK activities and downregulating MdME1, MdME4 and MdPEPCK2 expression. Surprisingly, calcium treatment changed the content of some free amino acids (GABA, proline, alanine, aspartic acid and glutamate), two of which (glutamate and GABA) are primary metabolites of the GABA pathway. Furthermore, calcium application enhanced GABA pathway activity by increasing MdGAD1, MdGAD2, MdGABA-T1/2 and MdSSADH transcript levels.


Assuntos
Cálcio/farmacologia , Frutas/efeitos dos fármacos , Malatos/metabolismo , Malus/efeitos dos fármacos , Malus/metabolismo , Ácido gama-Aminobutírico/metabolismo , Aminoácidos/análise , Aminoácidos/metabolismo , Etilenos/metabolismo , Qualidade dos Alimentos , Frutas/química , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Malus/química , Malus/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
6.
Food Chem ; 338: 128055, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32950008

RESUMO

This study examined the ability of l-arginine, l-cysteine and l-methionine, to inhibit postharvest senescence of broccoli. Florets were dipped in aqueous solutions of the amino acids at concentrations from 1.0 to 100 mM and stored at 10 °C. A 5 mM dip was found to be optimal in delaying senescence as measured by retention of green colour, vitamin C and antioxidant activity, and a lower level of ethylene production, respiration, weight loss, phenylalanine ammonia lyase (PAL) activity and ion leakage with the benefits being similar for all three amino acids. Arginine, cysteine and methionine have Generally Recognised As Safe (GRAS) status and should have few impediments in obtaining regulatory approval for commercial use if similar effects were found for other leafy vegetables.


Assuntos
Arginina/farmacologia , Brassica/efeitos dos fármacos , Cisteína/farmacologia , Metionina/farmacologia , Proteínas de Plantas/metabolismo , Amônia-Liases/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Brassica/metabolismo , Etilenos/metabolismo , Fatores de Tempo
7.
Postepy Biochem ; 66(1): 62-71, 2020 03 31.
Artigo em Polonês | MEDLINE | ID: mdl-33320480

RESUMO

Hypoxia in plants is a usually the result of heavy rainfall and the subsequent flooding. All current climate models indicate a notable increase in extreme weather over the coming years. Depending on the species and geographical location, plants have developed two distinct strategies for hypoxia stress adaptation: escape and quiescence. The escape strategy involves rapid growth of part of the shoot above the water level whe­reas the second strategy requires a significant reduction in the metabolic rate of the plant in order to survive until the negative environmental conditions pass. These processes are primarily regulated by ethylen in addition to the transcription factor, ERF (ethylen response factor), which enables the transcription of hypoxia response genes. These processes are primarily regulated by ethylen in addition to the transcription factors, ERFs (ethylen response factors), which enables the transcription of hypoxia response genes. Most ERF genes are constitutively trans­cribed independently of oxygen concentration. However, post-translational modification of the N-terminus of ERFs leads to their degradation in plants growing under physiological conditions. During hypoxia there is an increase in the expression level of genes associated with carbon, nitrogen, glycolysis or anaerobic respiration. However, as shown by studies using ribosome profiling, in order to save energy, plants under hypoxic stress strongly inhibit the process of initiating translation. The regulation of gene expression under stress conditions is also influen­ced by the accumulation of poly(A) RNA in the cell nucleus and cytoplasmic stress granules.


Assuntos
Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Oxigênio/metabolismo , Plantas/genética , Plantas/metabolismo , Estresse Fisiológico/genética , Transcriptoma/genética , Reguladores de Crescimento de Planta/metabolismo , Fatores de Transcrição/metabolismo
8.
PLoS One ; 15(10): e0235446, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33002000

RESUMO

We recently described a regulatory loop, which we termed autoregulation of infection (AOI), by which Sinorhizobium meliloti, a Medicago endosymbiont, downregulates the root susceptibility to secondary infection events via ethylene. AOI is initially triggered by so-far unidentified Medicago nodule signals named signal 1 and signal 1' whose transduction in bacteroids requires the S. meliloti outer-membrane-associated NsrA receptor protein and the cognate inner-membrane-associated adenylate cyclases, CyaK and CyaD1/D2, respectively. Here, we report on advances in signal 1 identification. Signal 1 activity is widespread as we robustly detected it in Medicago nodule extracts as well as in yeast and bacteria cell extracts. Biochemical analyses indicated a peptidic nature for signal 1 and, together with proteomic analyses, a universally conserved Medicago ribosomal protein of the uL2 family was identified as a candidate signal 1. Specifically, MtRPuL2A (MtrunA17Chr7g0247311) displays a strong signal activity that requires S. meliloti NsrA and CyaK, as endogenous signal 1. We have shown that MtRPuL2A is active in signaling only in a non-ribosomal form. A Medicago truncatula mutant in the major symbiotic transcriptional regulator MtNF-YA1 lacked most signal 1 activity, suggesting that signal 1 is under developmental control. Altogether, our results point to the MtRPuL2A ribosomal protein as the candidate for signal 1. Based on the Mtnf-ya1 mutant, we suggest a link between root infectiveness and nodule development. We discuss our findings in the context of ribosomal protein moonlighting.


Assuntos
Medicago truncatula , Proteínas de Plantas/metabolismo , Proteínas Ribossômicas/metabolismo , Nódulos Radiculares de Plantas/metabolismo , Sinorhizobium meliloti/metabolismo , Coinfecção/prevenção & controle , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Medicago truncatula/genética , Medicago truncatula/metabolismo , Medicago truncatula/microbiologia , Imunidade Vegetal/genética , Proteínas de Plantas/genética , Nodulação/fisiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Proteínas Ribossômicas/genética , Nódulos Radiculares de Plantas/microbiologia , Transdução de Sinais , Simbiose
9.
PLoS One ; 15(9): e0238140, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881943

RESUMO

Vitamin E acetate (VEA) is strongly linked to the outbreak of electronic-cigarette or vaping product use-associated lung injury (EVALI). It has been proposed that VEA decomposition to ketene-a respiratory poison that damages lungs at low ppm levels-may play a role in EVALI. However, there is no information available on the temperature at which VEA decomposes and how this correlates with the vaping process. We have studied the temperature-dependent kinetics of VEA decomposition using quantum chemical and statistical mechanical modelling techniques, developing a chemical kinetic model of the vaping process. This model predicts that, under typical vaping conditions, the use of VEA contaminated e-cigarette products is unlikely to produce ketene at harmful levels. However, at the high temperatures encountered at low e-cigarette product levels, which produce 'dry hits', ketene concentrations are predicted to reach acutely toxic levels in the lungs (as high as 30 ppm). We therefore hypothesize that dry hit vaping of e-cigarette products containing VEA contributes to EVALI.


Assuntos
Etilenos/metabolismo , Cetonas/metabolismo , Lesão Pulmonar/patologia , Vaping/efeitos adversos , Vitamina E/metabolismo , Etilenos/química , Etilenos/toxicidade , Humanos , Cetonas/química , Cetonas/toxicidade , Cinética , Lesão Pulmonar/induzido quimicamente , Temperatura , Vitamina E/química
10.
PLoS One ; 15(8): e0238055, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845898

RESUMO

Lodgepole pine, a prominent Pinaceae tree species native to western North America, is well-known for its ability to thrive in highly disturbed and degraded areas. One such area is the Sub-Boreal Pine-Spruce xeric-cold (SBPSxc) region in British Columbia, Canada, which is characterized by weakly-developed, parched soils that lack an organic forest floor and essential plant-available nutrients. We hypothesized that plant growth-promoting bacteria could play a significant role in sustaining the growth of lodgepole pine trees in the SBPSxc region. Testing this hypothesis, we evaluated plant growth-promoting abilities of six endophytic bacterial strains previously isolated from lodgepole pine trees growing in this region. These bacterial strains significantly enhanced the length and biomass of their natural host (lodgepole pine) as well as a foreign host (hybrid white spruce) in a 540-day long greenhouse trial. This growth stimulation could be linked to the diverse plant growth-promoting (PGP) abilities detected in these strains using in vitro assays for inorganic/organic phosphate-solubilization, siderophore production IAA production, ACC deaminase activity, lytic enzymes (chitinase, ß-1,3-glucanase, protease, and cellulase) activity, ammonia production and catalase activity. ACC deaminase activity was also detected in vivo for all strains using ethylene-sensitive plants-canola and tomato. Notably, strains belonging to the Burkholderiaceae family (HP-S1r, LP-R1r and LP-R2r) showed the greatest potential in all PGP assays and enhanced pine and spruce seedling length and biomass by up to 1.5-fold and 4-fold, respectively. Therefore, such bacterial strains with multifarious PGP abilities could be crucial for survival and growth of lodgepole pine trees in the SBPSxc region and could potentially be utilized as bioinoculant for Pinaceae trees in highly disturbed and nutrient-poor ecosystems.


Assuntos
Bactérias/isolamento & purificação , Pinaceae/crescimento & desenvolvimento , Biomassa , Fosfatos de Cálcio/química , Fosfatos de Cálcio/metabolismo , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Ecossistema , Etilenos/metabolismo , Ácidos Indolacéticos/metabolismo , Picea/crescimento & desenvolvimento , Picea/metabolismo , Picea/microbiologia , Pinaceae/metabolismo , Pinaceae/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/microbiologia , Plântula/fisiologia , Sideróforos/metabolismo
11.
PLoS One ; 15(8): e0238144, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32857790

RESUMO

The efficacy of auxinic herbicides, a valuable weed control tool for growers worldwide, has been shown to vary with the time of day in which applications are made. However, little is known about the mechanisms causing this phenomenon. Investigating the differential in planta behavior of these herbicides across different times of application may grant an ability to advise which properties of auxinic herbicides are desirable when applications must be made around the clock. Radiolabeled herbicide experiments demonstrated a likely increase in ATP-binding cassette subfamily B (ABCB)-mediated 2,4-D and dicamba transport in Palmer amaranth (Amaranthus palmeri S. Watson) at simulated dawn compared to mid-day, as dose response models indicated that many orders of magnitude higher concentrations of N-1-naphthylphthalamic acid (NPA) and verapamil, respectively, are required to inhibit translocation by 50% at simulated sunrise compared to mid-day. Gas chromatographic analysis displayed that ethylene evolution in A. palmeri was higher when dicamba was applied during mid-day compared to sunrise. Furthermore, it was found that inhibition of translocation via 2,3,5-triiodobenzoic acid (TIBA) resulted in an increased amount of 2,4-D-induced ethylene evolution at sunrise, and the inhibition of dicamba translocation via NPA reversed the difference in ethylene evolution across time of application. Dawn applications of these herbicides were associated with increased expression of a putative 9-cis-epoxycarotenoid dioxygenase biosynthesis gene NCED1, while there was a notable lack of trends observed across times of day and across herbicides with ACS1, encoding 1-aminocyclopropane-1-carboxylic acid synthase. Overall, this research indicates that translocation is differentially regulated via specific protein-level mechanisms across times of application, and that ethylene release, a chief phytotoxic process involved in the response to auxinic herbicides, is related to translocation. Furthermore, transcriptional regulation of abscisic acid involvement in phytotoxicity and/or translocation are suggested.


Assuntos
Amaranthus/efeitos dos fármacos , Amaranthus/fisiologia , Resistência a Herbicidas/fisiologia , Herbicidas/farmacologia , Fotoperíodo , Ácido 2,4-Diclorofenoxiacético/farmacologia , Dicamba/farmacologia , Relação Dose-Resposta a Droga , Etilenos/metabolismo , Ftalimidas/metabolismo , Proteínas de Plantas/metabolismo , Ácidos Tri-Iodobenzoicos/metabolismo , Verapamil/metabolismo
12.
Nat Commun ; 11(1): 4082, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32796832

RESUMO

The phytohormone ethylene has numerous effects on plant growth and development. Its immediate precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), is a non-proteinogenic amino acid produced by ACC SYNTHASE (ACS). ACC is often used to induce ethylene responses. Here, we demonstrate that ACC exhibits ethylene-independent signaling in Arabidopsis thaliana reproduction. By analyzing an acs octuple mutant with reduced seed set, we find that ACC signaling in ovular sporophytic tissue is involved in pollen tube attraction, and promotes secretion of the pollen tube chemoattractant LURE1.2. ACC activates Ca2+-containing ion currents via GLUTAMATE RECEPTOR-LIKE (GLR) channels in root protoplasts. In COS-7 cells expressing moss PpGLR1, ACC induces the highest cytosolic Ca2+ elevation compared to all twenty proteinogenic amino acids. In ovules, ACC stimulates transient Ca2+ elevation, and Ca2+ influx in octuple mutant ovules rescues LURE1.2 secretion. These findings uncover a novel ACC function and provide insights for unraveling new physiological implications of ACC in plants.


Assuntos
Arabidopsis/metabolismo , Etilenos/metabolismo , Óvulo Vegetal/metabolismo , Tubo Polínico/metabolismo , Aminoácidos Cíclicos/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cálcio/metabolismo , Regulação da Expressão Gênica de Plantas , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Liases/metabolismo , Reguladores de Crescimento de Planta/metabolismo
13.
Ecotoxicol Environ Saf ; 201: 110804, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32502907

RESUMO

Phenanthrene (PHE) is harmful to human health and is difficult to be eliminated from environment. In this study, an aerobic bacterium capable of use PHE as a sole carbon source and energy was isolated and classified as Klebsiella sp. PD3 according to 16S rDNA analysis. The degradation efficiency of PHE reached to about 78.6% after 12 days of incubation with strain PD3. Identification of metabolites formed during PHE degradation process by this strain was carried out by GC-MS. The first degradation step of PHE by PD3 was proposed to generate 1-hydroxy-2-naphthoic acid. Two subsequent different routes for the metabolism of 1-hydroxy-2-naphthoic acid were proposed. Strain PD3 also showed two plant growth promoting properties like phosphate solubilization and ACC deaminase activity. Inoculation with Klebsiella sp. PD3 significantly improved growth performance, biomass production, seed germination rate, photosynthetic capacity, antioxidant levels, relative water content and chlorophyll accumulation in rice (Oryza sativa L.) plants under PHE stress conditions in comparison with non-inoculation treatment. Moreover, PD3-inoculated rice showed lower ROS accumulation, ethylene production, ACC content, ACC oxidase activity and electrolyte leakage under PHE treatment compared to non-inoculated ones. The combination use of rice plants and strain PD3 was also shown to enhance the removal efficiency of PHE from the soil and decline the PHE accumulation in plants. Synergistic use of plants and bacteria with PHE degradation ability and PGPR attributes to remediate the PHE-contaminated soil will be an important and effective way in the phytoremediation of PHE-contaminated soils.


Assuntos
Adaptação Fisiológica , Klebsiella/metabolismo , Oryza/crescimento & desenvolvimento , Fenantrenos/análise , Microbiologia do Solo , Poluentes do Solo/análise , Biodegradação Ambiental , Clorofila/metabolismo , Etilenos/metabolismo , Klebsiella/isolamento & purificação , Oryza/metabolismo , Oryza/microbiologia , Estresse Oxidativo/efeitos dos fármacos , Fenantrenos/metabolismo , Solo/química , Poluentes do Solo/metabolismo
14.
Mol Genet Genomics ; 295(4): 941-956, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32350607

RESUMO

Water stress is the most important adverse factor limiting rice production. Too much water leads to flood and too little leads to drought. Floods and droughts can severely damage crop at different times of the rice life cycle. So the research on submergence tolerance and drought resistance of rice is particularly urgent. In this study, we reported that OsEBP89 (Oryza sativa Ethylene-responsive element binding protein, clone 89), a member of the AP2/ERF subfamily, is involved in a novel signal transduction associated with the tolerance to drought and submergence stress. OsEBP89 was found to be strongly inhibited by drought stress and promoted by submergence. The OsEBP89 protein was located at the nucleus in the rice protoplast. Loss of OsEBP89 was found to improve the seed germination under submerged conditions and also enhanced the tolerance to drought stress throughout growth stage. Additionally, OsEBP89 knockout rice plants increased the accumulation of proline, improved the ability to scavenge ROS compared to overexpression lines and wild type after PEG treatment. Transcriptome data indicates that knockout of OsEBP89 improved the expression of specific genes in response to adverse factors, such as OsAPX1, OsHsfA3, and OsP5CS. Further results indicate that OsEBP89 can interact with and be phosphorylated by SnRK1α (sucrose non-fermenting-1-related protein kinase-1 gene). These findings provide insight into the mechanism of abiotic stress tolerance, and suggest OsEBP89 as a new genetic engineering resource to improve abiotic stress tolerance in rice.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Proteínas de Homeodomínio/genética , Oryza/genética , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Adaptação Fisiológica/genética , Arabidopsis/genética , Secas , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Técnicas de Inativação de Genes , Oryza/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/genética , Fatores de Transcrição/genética , Áreas Alagadas
15.
Plant Sci ; 294: 110464, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32234220

RESUMO

Both salicylic acid (SA) and ethylene induce stomatal closure and positively regulate stomatal immunity, but their interactions in guard cell signaling are unclear. Here, we observed that SA induced the expression of ethylene biosynthetic genes; the production of ethylene, reactive oxygen species (ROS) and nitric oxide (NO); and stomatal closure in Arabidopsis thaliana. However, SA-induced stomatal closure was inhibited by an ethylene biosynthetic inhibitor and mutations in ethylene biosynthetic genes, ethylene-signaling genes [RESPONSE TO ANTAGONIST 1 (RAN1), ETHYLENE RESPONSE 1 (ETR1), ETHYLENE INSENSITIVE 2 (EIN2), EIN3 and ARABIDOPSIS RESPONSE REGULATOR 2 (ARR2)], NADPH oxidase genes [ATRBOHD and ATRBOHF], and nitrate reductase genes (NIA1 and NIA2). Furthermore, SA-triggered ROS production in guard cells was impaired in ran1, etr1, AtrbohD and AtrbohF, but not in ein2, ein3 or arr2. SA-triggered NO production was impaired in all ethylene-signaling mutants tested and in nia1 and nia2. The stomata of mutants for CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) showed constitutive ROS and NO production and closure. These results indicate that ethylene mediates SA-induced stomatal closure by activating ATRBOHD/F-mediated ROS synthesis in an RAN1-, ETR1- and CTR1-dependent manner. This in turn induces NIA1/2-mediated NO production and subsequent stomatal closure via the ETR1, EIN2, EIN3 and ARR2-dependent pathway(s).


Assuntos
Arabidopsis/metabolismo , Óxido Nítrico/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas de Arabidopsis/metabolismo , Etilenos/metabolismo , NADPH Oxidases/metabolismo , Estômatos de Plantas/metabolismo , Ácido Salicílico/metabolismo
16.
Int J Mol Sci ; 21(8)2020 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-32290539

RESUMO

Target of rapamycin (TOR) acts as a master regulator in coordination of cell growth with energy and nutrient availability. Despite the increased appreciation of the essential role of the TOR complex in interaction with phytohormone signaling, little is known about its function on ethylene signaling. Here, through expression analysis, genetic and biochemical approaches, we reveal that TOR functions in the regulation of ethylene signals. Transcriptional analysis indicates that TOR inhibition by AZD8055 upregulated senescence- and ethylene-related genes expression. Furthermore, ethylene insensitive mutants like etr1-1, ein2-5 and ein3 eil1, showed more hyposensitivity to AZD8055 than that of WT in hypocotyl growth inhibition. Similarly, blocking ethylene signals by ethylene action inhibitor Ag+ or biosynthesis inhibitor aminoethoxyvinylglycine (AVG) largely rescued hypocotyl growth even in presence of AZD8055. In addition, we also demonstrated that Type 2A phosphatase-associated protein of 46 kDa (TAP46), a downstream component of TOR signaling, physically interacts with 1-aminocy-clopropane-1-carboxylate (ACC) synthase ACS2 and ACS6. Arabidopsis overexpressing ACS2 or ACS6 showed more hypersensitivity to AZD8055 than WT in hypocotyl growth inhibition. Moreover, ACS2/ACS6 protein was accumulated under TOR suppression, implying TOR modulates ACC synthase protein levels. Taken together, our results indicate that TOR participates in negatively modulating ethylene signals and the molecular mechanism is likely involved in the regulation of ethylene biosynthesis by affecting ACSs in transcription and protein levels.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Etilenos/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Reguladores de Crescimento de Planta/metabolismo , RNA de Plantas/genética , Transdução de Sinais/fisiologia
17.
Biochem Biophys Res Commun ; 525(2): 491-497, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32111354

RESUMO

Ethylene is a gaseous phytohormone that is perceived by two-component histidine kinase-type receptors. Recent studies identified choline transporter-like 1 (CTL1) essential for Arabidopsis growth and development, including apical hook development in the etiolated seedlings. Here, we report that CTL1 contributes to apical hook development by enhancing ethylene response. The expression of CTL1 was highly correlated with the intensity of ethylene response and was enriched in the apical hook, cotyledon tip and hypocotyl. Genetic analysis showed that the dark-grown ctl1 mutant displayed a defect in ethylene-induced apical hook development as compared with the wild type. Accordingly, the expression of ethylene signaling reporter EBS::GUS in ctl1 mutant was greatly reduced in leaves, apical hook, hypocotyl and root, suggesting that the disruption of CTL1 impairs the ethylene signaling. Furthermore, protein-protein interaction assays demonstrated that CTL1 may interact with ethylene receptors, including ETR1, ETR2, ERS1, ERS2. Importantly, the abundance of CTL1 was diminished when ETR1 was disrupted upon ethylene response. Taken together, our results suggest that CTL1 functions as a positive regulator in ethylene signaling which in turn contributes to apical hook development of etiolated plant seedlings.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Membrana Transportadoras/metabolismo , Plântula/crescimento & desenvolvimento , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/genética , Reguladores de Crescimento de Planta/metabolismo , Plântula/genética , Plântula/metabolismo , Regulação para Cima
18.
Appl Environ Microbiol ; 86(11)2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32198172

RESUMO

Azotobacter vinelandii is an obligate aerobic diazotroph with a verified transient ability to reduce carbon monoxide to ethylene by its vanadium nitrogenase. In this study, we implemented an industrially relevant continuous two-stage stirred-tank system for in vivo biotransformation of a controlled supply of air enriched with 5% carbon monoxide to 302 µg ethylene g-1 glucose consumed. To attain this value, the process required overcoming critical oxygen limitations during cell proliferation while simultaneously avoiding the A. vinelandii respiratory protection mechanism that negatively impacts in vivo nitrogenase activity. Additionally, process conditions allowed the demonstration of carbon monoxide's solubility as a reaction-limiting factor and a competitor with dinitrogen for the vanadium nitrogenase active site, implying that excess intracellular carbon monoxide could lead to a cessation of cell proliferation and ethylene formation as shown genetically using a new strain of A. vinelandii deficient in carbon monoxide dehydrogenase.IMPORTANCE Ethylene is an essential commodity feedstock used for the generation of a variety of consumer products, but its generation demands energy-intensive processes and is dependent on nonrenewable substrates. This work describes a continuous biological method for investigating the nitrogenase-mediated carbon monoxide reductive coupling involved in ethylene production using whole cells of Azotobacter vinelandii If eventually adopted by industry, this technology has the potential to significantly reduce the total energy input required and the ethylene recovery costs, as well as decreasing greenhouse gas emissions associated with current production strategies.


Assuntos
Azotobacter vinelandii/metabolismo , Monóxido de Carbono/metabolismo , Etilenos/metabolismo , Biocombustíveis , Reatores Biológicos
19.
Plant Physiol Biochem ; 151: 124-131, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32220785

RESUMO

Seed germination and early seedling development are two critical phases in plant lifecycle that largely determine crop yield. Phytohormones play an essential role in governing these developmental processes; of these, ethylene (ET; C2H4), the smallest gaseous hormone, plays a major role via crosstalk with other hormones. Typically, the mechanism of hormone (for instance, auxin, cytokinins, ET, and gibberellins) action is determined by cellular context, revealing either synergistic or antagonistic relations. Significant progress has been made, so far, on unveiling ET crosstalk with other hormones and environmental signals, such as light. In particular, stimulatory and inhibitory effects of ET on hypocotyl growth in light and dark, respectively, and its interaction with other hormones provide an ideal model to study the growth-regulatory pathways. In this review, we aim at exploring the mechanisms of multifarious phenomena that occur via ET crosstalk during the germination of seeds (overcoming dormancy), and all through the development of seedlings. Understanding the remarkably complex mechanism of ET crosstalk that emerges from the interaction between hormones and other molecular players to modulate plant growth, remains a challenge in plant developmental biology.


Assuntos
Etilenos/metabolismo , Germinação , Plântula/fisiologia , Sementes/fisiologia , Transdução de Sinais , Reguladores de Crescimento de Planta/fisiologia
20.
Planta ; 251(4): 84, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32189077

RESUMO

MAIN CONCLUSION: In response to low nitrogen stress, multiple hormones together with nitric oxide signaling pathways work synergistically and antagonistically in crop root elongation. Changing root morphology allows plants to adapt to soil nutrient availability. Nitrogen is the most important essential nutrient for plant growth. An important adaptive strategy for crops responding to nitrogen deficiency is root elongation, thereby accessing increased soil space and nitrogen resources. Multiple signaling pathways are involved in this regulatory network, working together to fine-tune root elongation in response to soil nitrogen availability. Based on existing research, we propose a model to explain how different signaling pathways interact to regulate root elongation in response to low nitrogen stress. In response to a low shoot nitrogen status signal, auxin transport from the shoot to the root increases. High auxin levels in the root tip stimulate the production of nitric oxide, which promotes the synthesis of strigolactones to accelerate cell division. In this process, cytokinin, ethylene, and abscisic acid play an antagonistic role, while brassinosteroids and auxin play a synergistic role in regulating root elongation. Further study is required to identify the QTLs, genes, and favorable alleles which control the root elongation response to low nitrogen stress in crops.


Assuntos
Produtos Agrícolas/metabolismo , Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Ácido Abscísico/metabolismo , Brassinosteroides/metabolismo , Citocininas/metabolismo , Etilenos/metabolismo , Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Meristema/metabolismo , Óxido Nítrico/metabolismo , Desenvolvimento Vegetal , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais , Estresse Fisiológico
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