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Kućko A, Wilmowicz E, Ostrowski M. Spatio-temporal IAA gradient is determined by interactions with ET and governs flower abscission. JOURNAL OF PLANT PHYSIOLOGY 2019; 236:51-60. [PMID: 30878877 DOI: 10.1016/j.jplph.2019.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/10/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
The abscission zone (AZ) is a specialized tissue that usually develops at the base of an organ and is highly sensitive to phytohormones, e.g., abscisic acid (ABA), ethylene (ET), and gibberellins (GAs). A current model of organ abscission assumes that the formation of an auxin gradient around the AZ area determines the time of shedding; however, that thesis is supported by studies that are primarily concerned with auxin transporters. To better understand the events underlying the progression of abscission, we focused for the first time on indole-3-acetic acid (IAA) distribution following AZ activation. We performed a series of immunolocalization studies in proximal and distal regions of floral AZ cells in yellow lupine, which is an agriculturally important legume. The examined phytohormone was abundant in natural active AZ cells, as well as above and below parts of this structure. A similar gradient of IAA was observed during the early steps of abscission, which was induced artificially by flower removal. Surprisingly, IAA was not detected in inactive AZ cells. This paper is also a consequence of our comprehensive studies concerning the phytohormonal regulation of flower abscission in yellow lupine. We present new data on interactions between IAA and ET, previously pointed out as a strong modulator of flower separation. The detailed analysis shows that disruption of the natural auxin gradient around the AZ area through the application of synthetic IAA had a positive effect on ET biosynthesis genes. We proved that these changes are accompanied by an accumulation of the ET precursor. On the other hand, exposure to ET significantly affected IAA localization in the whole AZ area in a time-dependent manner. Our results provide insight into the existence of a spatio-temporal sequential pattern of the IAA gradient related to the abscission process; this pattern is maintained by interactions with ET. We present new valuable evidence for the existence of conservative mechanisms that regulate generative organ separation and can help to improve the yield of agronomically significant species in the future.
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Affiliation(s)
- Agata Kućko
- Chair of Plant Physiology and Biotechnology, Nicolaus Copernicus University, 1 LwowskaStreet, 87-100, Toruń, Poland; Chair of Plant Physiology and Biotechnology, University of Gdańsk, 59 Wita Stwosza, 80-308 Gdańsk, Poland.
| | - Emilia Wilmowicz
- Chair of Plant Physiology and Biotechnology, Nicolaus Copernicus University, 1 LwowskaStreet, 87-100, Toruń, Poland.
| | - Maciej Ostrowski
- Department of Biochemistry, Nicolaus Copernicus University, 1 LwowskaStreet, 87-100, Toruń, Poland.
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2
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Elías JM, Guerrero-Molina MF, Martínez-Zamora MG, Díaz-Ricci JC, Pedraza RO. Role of ethylene and related gene expression in the interaction between strawberry plants and the plant growth-promoting bacterium Azospirillum brasilense. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:490-496. [PMID: 29350442 DOI: 10.1111/plb.12697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/16/2018] [Indexed: 05/23/2023]
Abstract
Induced systemic resistance (ISR) is one of the indirect mechanisms of growth promotion exerted by plant growth-promoting bacteria, and can be mediated by ethylene (ET). We assessed ET production and the expression of related genes in the Azospirillum-strawberry plant interaction. Ethylene production was evaluated by gas chromatography in plants inoculated or not with A. brasilense REC3. Also, plants were treated with AgNO3 , an inhibitor of ET biosynthesis; with 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ET biosynthesis; and with indole acetic acid (IAA). Plant dry biomass and the growth index were determined to assess the growth-promoting effect of A. brasilense REC3 in strawberry plants. Quantitative real time PCR (qRT-PCR) was performed to analyse relative expression of the genes Faetr1, Faers1 and Faein4, which encode ET receptors; Factr1 and Faein2, involved in the ET signalling pathway; Faacs1 encoding ACC synthase; Faaco1 encoding ACC oxidase; and Faaux1 and Faami1 for IAA synthesis enzymes. Results showed that ET acts as a rapid and transient signal in the first 12 h post-treatment. A. brasilense REC3-inoculated plants had a significantly higher growth index compared to control plants. Modulation of the genes Faetr1, Faers1, Faein4, Factr1, Faein2 and Faaco1 indicated activation of ET synthesis and signalling pathways. The up-regulation of Faaux1 and Faami1 involved in IAA synthesis suggested that inoculation with A. brasilense REC3 induces production of this auxin, modulating ET signalling. Ethylene production and up-regulation of genes associated with ET signalling in strawberry plants inoculated with A. brasilense REC3 support the priming activation characteristic of ISR. This type of resistance and the activation of systemic acquired resistance previously observed in this interaction indicate that both are present in strawberry plants, could act synergistically and increase protection against pathogens.
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Affiliation(s)
- J M Elías
- Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - M F Guerrero-Molina
- Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
- Instituto Superior de Investigaciones Biológicas (INSIBIO CONICET-UNT), and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina
| | - M G Martínez-Zamora
- Instituto Superior de Investigaciones Biológicas (INSIBIO CONICET-UNT), and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina
| | - J C Díaz-Ricci
- Instituto Superior de Investigaciones Biológicas (INSIBIO CONICET-UNT), and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina
| | - R O Pedraza
- Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
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Shibuya K. Molecular aspects of flower senescence and strategies to improve flower longevity. BREEDING SCIENCE 2018; 68:99-108. [PMID: 29681752 PMCID: PMC5903976 DOI: 10.1270/jsbbs.17081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/14/2017] [Indexed: 05/06/2023]
Abstract
Flower longevity is one of the most important traits for ornamental plants. Ethylene plays a crucial role in flower senescence in some plant species. In several species that show ethylene-dependent flower senescence, genetic modification targeting genes for ethylene biosynthesis or signaling has improved flower longevity. Although little is known about regulatory mechanisms of petal senescence in flowers that show ethylene-independent senescence, a recent study of Japanese morning glory revealed that a NAC transcription factor, EPHEMERAL1 (EPH1), is a key regulator in ethylene-independent petal senescence. EPH1 is induced in an age-dependent manner irrespective of ethylene signal, and suppression of EPH1 expression dramatically delays petal senescence. In ethylene-dependent petal senescence, comprehensive transcriptome analyses revealed the involvement of transcription factors, a basic helix-loop-helix protein and a homeodomain-leucine zipper protein, in the transcriptional regulation of the ethylene biosynthesis enzymes. This review summarizes molecular aspects of flower senescence and discusses strategies to improve flower longevity by molecular breeding.
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Affiliation(s)
- Kenichi Shibuya
- Institute of Vegetable and Floriculture Science, NARO,
2-1 Fujimoto, Tsukuba, Ibaraki 305-0852,
Japan
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4
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Jakubowicz M, Gałgańska H, Nowak W, Sadowski J. Exogenously induced expression of ethylene biosynthesis, ethylene perception, phospholipase D, and Rboh-oxidase genes in broccoli seedlings. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:3475-91. [PMID: 20581125 PMCID: PMC2905205 DOI: 10.1093/jxb/erq177] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 05/21/2010] [Accepted: 05/25/2010] [Indexed: 05/20/2023]
Abstract
In higher plants, copper ions, hydrogen peroxide, and cycloheximide have been recognized as very effective inducers of the transcriptional activity of genes encoding the enzymes of the ethylene biosynthesis pathway. In this report, the transcriptional patterns of genes encoding the 1-aminocyclopropane-1-carboxylate synthases (ACSs), 1-aminocyclopropane-1-carboxylate oxidases (ACOs), ETR1, ETR2, and ERS1 ethylene receptors, phospholipase D (PLD)-alpha1, -alpha2, -gamma1, and -delta, and respiratory burst oxidase homologue (Rboh)-NADPH oxidase-D and -F in response to these inducers in Brassica oleracea etiolated seedlings are shown. ACS1, ACO1, ETR2, PLD-gamma1, and RbohD represent genes whose expression was considerably affected by all of the inducers used. The investigations were performed on the seedlings with (i) ethylene insensitivity and (ii) a reduced level of the PLD-derived phosphatidic acid (PA). The general conclusion is that the expression of ACS1, -3, -4, -5, -7, and -11, ACO1, ETR1, ERS1, and ETR2, PLD-gamma 1, and RbohD and F genes is undoubtedly under the reciprocal cross-talk of the ethylene and PA(PLD) signalling routes; both signals affect it in concerted or opposite ways depending on the gene or the type of stimuli. The results of these studies on broccoli seedlings are in agreement with the hypothesis that PA may directly affect the ethylene signal transduction pathway via an inhibitory effect on CTR1 (constitutive triple response 1) activity.
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Affiliation(s)
- Małgorzata Jakubowicz
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland.
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Ludwików A, Kierzek D, Gallois P, Zeef L, Sadowski J. Gene expression profiling of ozone-treated Arabidopsis abi1td insertional mutant: protein phosphatase 2C ABI1 modulates biosynthesis ratio of ABA and ethylene. PLANTA 2009; 230:1003-17. [PMID: 19705149 DOI: 10.1007/s00425-009-1001-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 08/05/2009] [Indexed: 05/09/2023]
Abstract
We report on the characterization of the interaction between reactive oxygen species signalling and abscisic acid (ABA)-mediated gene network in ozone (O(3)) stress response. To identify the stress-related signalling pathways and possible cross-talk controlled by an ABA-negative regulator, the protein phosphatase 2C abscisic acid insensitive1 (ABI1), we performed a genome-wide transcription profiling of O(3)-treated wild-type and ABI1 knockout (abi1td) plants. In addition, to better understand ABA signalling and the interactions between stress response pathways, we performed a microarray analysis of drought-treated plants. Functional categorization of the identified genes showed that ABI1 is involved in the modulation of several cellular processes including metabolism, transport, development, information pathways and variant splicing. Comparisons with available transcriptome data sets revealed the extent of ABI1 involvement in both ABA-dependent and ABA-independent gene expression. Furthermore, in O(3) stress the ABA hypersensitivity of abi1td resulted in a significant reduction of the ABA level, ethylene (ET) over-production and O(3) tolerance. Moreover, the physical interaction of ABI1 with ACC synthase2 and ACC synthase6 was shown. We provide a model explaining how ABI1 can regulate both ABA and ET biosynthesis. Altogether, our findings indicate that ABI1 plays the role of a general signal transducer linking ABA and ET biosynthesis as well as signalling pathways to O(3) stress tolerance.
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Affiliation(s)
- Agnieszka Ludwików
- Department of Biotechnology, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, 61-614 Poznan, Poland
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6
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Duguay J, Jamal S, Liu Z, Wang TW, Thompson JE. Leaf-specific suppression of deoxyhypusine synthase in Arabidopsis thaliana enhances growth without negative pleiotropic effects. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:408-20. [PMID: 16600425 DOI: 10.1016/j.jplph.2006.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 02/10/2006] [Indexed: 05/08/2023]
Abstract
Deoxyhypusine synthase (DHS) mediates the first of two enzymatic reactions required for the post-translational activation of eukaryotic translation initiation factor 5A (eIF5A), which in turn is thought to facilitate translation of specific mRNAs. Analyses of GUS activity in transgenic Arabidopsis plants expressing the GUS reporter gene under regulation of the promoter for AtDHS revealed that the expression of DHS changes both spatially and temporally as development progresses. In particular, DHS is expressed not only in rosette leaves, but also in the anthers of developing flowers. To determine the role of DHS in leaves, transgenic plants in which DHS was selectively suppressed in rosettes of Arabidopsis plants were prepared. This was achieved by expressing AtDHS 3'-UTR cDNA as a transgene under regulation of the promoter for AtRbcS2, a gene encoding the small subunit of Rubisco. The dominant phenotypic traits of the DHS-suppressed plants proved to be a dramatic enhancement of both vegetative and reproductive growth. As well, the onset of leaf senescence in the DHS-suppressed plants was delayed by approximately 1 week, but there was no change in the timing of bolting. In addition, there was no evidence for the negative pleiotropic effects, including stunted reproductive growth and reduced seed yield, noted previously for transgenic plants in which DHS was constitutively suppressed. The results indicate that DHS plays a pivotal role in both growth and senescence.
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Affiliation(s)
- Jeremy Duguay
- Department of Biology, University of Waterloo, Waterloo, Ont, Canada
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7
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Padham AK, Hopkins MT, Wang TW, McNamara LM, Lo M, Richardson LGL, Smith MD, Taylor CA, Thompson JE. Characterization of a plastid triacylglycerol lipase from Arabidopsis. PLANT PHYSIOLOGY 2007; 143:1372-84. [PMID: 17259290 PMCID: PMC1820909 DOI: 10.1104/pp.106.090811] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Accepted: 01/03/2007] [Indexed: 05/13/2023]
Abstract
Full-length cDNA corresponding to Arabidopsis (Arabidopsis thaliana) gene At2g31690, which has been annotated in GenBank as a putative triacylglycerol (TAG) lipase, was obtained by reverse transcription-polymerase chain reaction using RNA from senescing rosette leaves of Arabidopsis as a template. The cognate protein was found to contain the lipase active site sequence, and corresponding recombinant protein proved capable of deesterifying TAG. In vitro chloroplast import assays indicated that the lipase is targeted to chloroplasts. This was confirmed by confocal microscopy of rosette leaf tissue treated with fluorescein isocyanate-labeled, lipase-specific antibody, which revealed that lipase protein colocalizes with plastoglobular neutral lipids. Western-blot analysis indicated that the lipase is expressed in roots, inflorescence stems, flowers, siliques, and leaves and that it is strongly up-regulated in senescing rosette leaf tissue. Transgenic plants with suppressed lipase protein levels were obtained by expressing At2g31690 cDNA in antisense orientation under the regulation of a constitutive promoter. Transgenic plants bolted and flowered at the same time as wild-type plants, but were severely stunted and exhibited delayed rosette senescence. Moreover, the stunted growth phenotype correlated with irregular chloroplast morphology. The chloroplasts of transgenic plants were structurally deformed, had reduced abundance of thylakoids that were abnormally stacked, and contained more plastoglobular neutral lipids than chloroplasts of wild-type plants. These observations collectively indicate that this TAG lipase plays a role in maintaining the structural integrity of chloroplasts, possibly by mobilizing the fatty acids of plastoglobular TAG.
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Affiliation(s)
- Anita K Padham
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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8
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Wang TW, Zhang CG, Wu W, Nowack LM, Madey E, Thompson JE. Antisense suppression of deoxyhypusine synthase in tomato delays fruit softening and alters growth and development. PLANT PHYSIOLOGY 2005; 138:1372-82. [PMID: 15951486 PMCID: PMC1176410 DOI: 10.1104/pp.105.060194] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The effects of suppressing deoxyhypusine synthase (DHS) have been examined in tomato (Solanum lycopersicum cv UCT5). DHS mediates the first of two sequential enzymatic reactions that activate eukaryotic translation initiation factor-5A (eIF-5A) by converting a conserved Lys to the unusual amino acid, deoxyhypusine. DHS protein levels were suppressed in transgenic plants by expressing the 3'-untranslated region of tomato DHS under regulation of the constitutive cauliflower mosaic virus promoter. Fruit from the transgenic plants ripened normally, but exhibited delayed postharvest softening and senescence that correlated with suppression of DHS protein levels. Northern-blot analysis indicated that all four gene family members of tomato eIF-5A are expressed in fruit, and that three are up-regulated in parallel with enhancement of DHS mRNA as the fruit begin to senesce and soften. Transgenic plants in which DHS was more strongly suppressed were male sterile, did not produce fruit, and had larger, thicker leaves with enhanced levels of chlorophyll. The activity of PSII was 2 to 3 times higher in these transgenic leaves than in corresponding leaves of wild-type plants, and there was also enhanced deposition of starch in the stems. The data collectively indicate that suppression of DHS has pleiotropic effects on growth and development of tomato. This may, in turn, reflect the fact that there is a single DHS gene in tomato and that its cognate protein is involved in the activation of four distinct isoforms of eIF-5A.
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Affiliation(s)
- Tzann-Wei Wang
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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9
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Chou WC, Huang YW, Tsay WS, Chiang TY, Huang DD, Huang HJ. Expression of genes encoding the rice translation initiation factor, eIF5A, is involved in developmental and environmental responses. PHYSIOLOGIA PLANTARUM 2004; 121:50-57. [PMID: 15086817 DOI: 10.1111/j.0031-9317.2004.00292.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Eukaryotic translation initiation factor 5 A (eIF5A) is the only cellular protein known to contain the unusual amino acid hypusine. However, the precise cellular function of eIF5A is to date unknown. In the present study, we report on the characterization of two cDNA clones encoding eIF5A in rice (Oryza sativa). Sequence analysis revealed that the two cDNAs share 93% amino acid sequence identity. Phylogenetic analysis of the eIF5A genes revealed paraphyly of OseIF5A-1 and OseIF5A-2. Analysis at the mRNA level has shown that OseIF5A-1 and OseIF5A-2 are expressed in rice leaves and panicles and high relative amounts of both genes were detected in old leaves. In addition, both OseIF5A-1 and OseIF5A-2 were spatially regulated during rice leaf development. In suspension-cultured cells, the transcripts of OseIF5A genes were strongly reduced after sugar starvation. Abiotic stresses, salt and heavy metal, induce the accumulation of OseIF5A-1 and OseIF5A-2 mRNAs in rice cells. These results suggested that both OseIF5A genes might be regulated by plant development and environmental stresses.
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Affiliation(s)
- Wan-Chi Chou
- Department of Biology, Center for Biosciences and Biotechology, National Cheng Kung University, Tainan 701, Taiwan
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Wang D, Fan J, Ranu RS. Cloning and expression of 1-aminocyclopropane-1-carboxylate synthase cDNA from rosa (Rosa x hybrida). PLANT CELL REPORTS 2004; 22:422-429. [PMID: 14579075 DOI: 10.1007/s00299-003-0721-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Revised: 09/05/2003] [Accepted: 09/08/2003] [Indexed: 05/24/2023]
Abstract
The role of 1-aminocyclopropane-1-carboxylate (ACC) synthase in rose flower petal senescence was investigated. A cDNA library from senescing petals of rose ( Rosa x hybrid cv. Kardinal) prepared in lambdacDNA ZAP Express Vector was probed with a rose-specific 400-bp probe, and seven putative positive ACC synthase clones were isolated. Except for differences in length, the sequences of these clones were identical. A full-length clone, RKacc7, 1,750 bp long, coded for an open reading frame of 480 amino acids that contained the 11 conserved amino acid residues, the substrate and pyridoxal 5'-phosphate binding sites, all of which are characteristic of all ACC synthases. The transcripts prepared in vitro from the full-length clone when translated in rabbit reticulocyte lysates exhibited a 55-KDa polypeptide that comigrated with a polypeptide synthesized from a mRNA fraction isolated from senescing petals, and both were immunoselected by anti-ACC synthase antibodies. Reverse transcriptase-PCR-based studies showed that in planta RKacc7 is specifically expressed in rose petals, ovary and sepals. The expression of ACC synthase increased dramatically as the flower matured to senescence and also correlated positively with ethylene levels. The results of genomic Southern blots probed with RKacc7 are consistent with a pattern expected from a multigene family.
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Affiliation(s)
- D Wang
- Laboratory of Plant Molecular Biology/Biotechnology, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523-1177, USA
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Wang TW, Lu L, Zhang CG, Taylor C, Thompson JE. Pleiotropic effects of suppressing deoxyhypusine synthase expression in Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY 2003; 52:1223-35. [PMID: 14682621 DOI: 10.1023/b:plan.0000004332.80792.4d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A full-length cDNA clone encoding deoxyhypusine synthase (DHS) was isolated from a cDNA expression library prepared from senescing leaves of Arabidopsis thaliana. Southern blot analysis indicated that DHS is encoded by a single-copy gene in Arabidopsis. During leaf development, the abundance of DHS mRNA in the third pair of rosette leaves peaked at days 14 and 35 after emergence coincident with the initiation of bolting and the later stages of leaf senescence, respectively. These changes in DHS expression were paralleled by corresponding changes in transcript abundance for eIF-5A1, one of three isoforms of eIF-5A in Arabidopsis. Levels of DHS transcript also increased in detached leaves coincident with post-harvest senescence. DHS was suppressed in transgenic plants by introducing antisense full-length or 3'-untranslated Arabidopsis DHS cDNA under the regulation of the constitutive cauliflower mosaic virus (CaMV-35S) promoter. Plants expressing the antisense transgenes had reduced levels of leaf DHS protein and, depending on the level of DHS suppression, exhibited delayed natural leaf senescence, delayed bolting, increased rosette leaf and root biomass, and enhanced seed yield. Suppression of DHS also delayed premature leaf senescence induced by drought stress resulting in enhanced survival in comparison with wild-type plants. In addition, detached leaves from DHS-suppressed plants exhibited delayed post-harvest senescence. These pleiotropic effects of DHS suppression indicate that the protein plays a central role in plant development and senescence.
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Affiliation(s)
- Tzann-Wei Wang
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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12
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Rodriguez-Gacio Md MDC, Matilla AJ. The last step of the ethylene biosynthesis pathway in turnip tops (Brassica rapa) seeds: Alterations related to development and germination and its inhibition during desiccation. PHYSIOLOGIA PLANTARUM 2001; 112:273-279. [PMID: 11454233 DOI: 10.1034/j.1399-3054.2001.1120216.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The involvement of ethylene in zygotic embryogenesis is a little known aspect of the growth and development in higher plants. In the present work, we study the alterations of the last step of the ethylene biosynthesis pathway during the formation period of turnip tops (Brassica rapa cv. Rapa) seeds and its repercussions in the germination process and post-germinative growth. For this, we chose 11 different phases of silique development, the first being the recently fertilized pistil and the last being the silique just prior to its dehiscence (ca. 2 months post-anthesis). In the 11 phases, ethylene production was detected in both whole silique (with or without seeds) and in the seeds enclosed by the silique wall. The levels of ACC, ACO and ethylene production proved high in seeds belonging to: (1) the pod in the very early phases, when the seeds were growing but without photosynthetic competence; (2) the silique at maximum growth, in which the seeds will initiate desiccation and loss of photosynthetic activity. During the phases prior to dehiscence, there was a marked inhibition in the last step of the ethylene biosynthesis pathway. In viable dry seeds, no ACO activity was detected and the ACC levels were 4-fold lower than at the onset of the silique senescence. Germination brings about a net synthesis of ACC with respect of the stores dry seed. This fact, together with other results presented in this work, point towards, as in other seeds, a dependence of ethylene synthesis for radicle emergence. The possible role played by the silique wall in the control of ethylene biosynthesis during zygotic embryogenesis, as well as the participation of ethylene as a hormonal signal in the triggering of seed desiccation in Brassica rapa cv. Rapa, are discussed in depth.
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Affiliation(s)
- María del Carmen Rodriguez-Gacio Md
- Departamento de Biología Vegetal, Laboratorio de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, A Coruña, Spain
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13
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Wang TW, Lu L, Wang D, Thompson JE. Isolation and characterization of senescence-induced cDNAs encoding deoxyhypusine synthase and eucaryotic translation initiation factor 5A from tomato. J Biol Chem 2001; 276:17541-9. [PMID: 11278418 DOI: 10.1074/jbc.m008544200] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Full-length cDNA clones encoding deoxyhypusine synthase (DHS) and eucaryotic initiation factor 5A (eIF-5A) have been isolated from a cDNA expression library prepared from tomato leaves (Lycopersicon esculentum, cv. Match) exposed to environmental stress. DHS mediates the first of two enzymatic reactions that activate eIF-5A by converting a conserved lysine to the unusual amino acid, deoxyhypusine. Recombinant protein obtained by expressing tomato DHS cDNA in Escherichia coli proved capable of carrying out the deoxyhypusine synthase reaction in vitro in the presence of eIF-5A. Of particular interest is the finding that DHS mRNA and eIF-5A mRNA show a parallel increase in abundance in senescing tomato flowers, senescing tomato fruit, and environmentally stressed tomato leaves exhibiting programmed cell death. Western blot analyses indicated that DHS protein also increases at the onset of senescence. It is apparent from previous studies with yeast and mammalian cells that hypusine-modified eIF-5A facilitates the translation of a subset of mRNAs mediating cell division. The present study provides evidence for senescence-induced DHS and eIF-5A in tomato tissues that may facilitate the translation of mRNA species required for programmed cell death.
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Affiliation(s)
- T W Wang
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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15
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Schlagnhaufer CD, Arteca RN, Pell EJ. Sequential expression of two 1-aminocyclopropane-1-carboxylate synthase genes in response to biotic and abiotic stresses in potato (Solanum tuberosum L.) leaves. PLANT MOLECULAR BIOLOGY 1997; 35:683-688. [PMID: 9426590 DOI: 10.1023/a:1005857717196] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plants produce ethylene in response to many biotic and abiotic stresses. In response to ozone the foliage of potato plants sequentially expressed two ACC synthase genes (ST-ACS4, ST-ACS5). The same expression pattern of the two genes also occurred in response to Cu2+ and infection with Alternaria solani. ST-ACS5 expression increases very rapidly reaching a maximum earlier than ST-ACS4 transcripts, after which ST-ACS5 expression declines. ST-ACS4 expression increases at a slower rate and reaches its maximum after ST-ACS5. The sequential nature of expression argues that the two genes have different signal transduction and gene regulatory mechanisms.
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Affiliation(s)
- C D Schlagnhaufer
- Department of Horticulture, Pennsylvania State University, University Park 16802, USA
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Clark DG, Richards C, Hilioti Z, Lind-Iversen S, Brown K. Effect of pollination on accumulation of ACC synthase and ACC oxidase transcripts, ethylene production and flower petal abscission in geranium (Pelargonium x hortorum L.H. Bailey). PLANT MOLECULAR BIOLOGY 1997; 34:855-65. [PMID: 9290638 DOI: 10.1023/a:1005877809905] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Self-pollination of diploid zonal geranium (Pelargonium x hortorum L.H. Bailey) florets leads to a dramatic rise in ethylene production, followed by abscission within 4 h. Neither wounding of the stigma, pollination with tetraploid pollen, nor heat-killed self pollen could elicit as much ethylene production and petal abscission as self-pollination. A cDNA sharing sequence identity with ACC synthase (GACS2) and three different cDNAs sharing sequence identity with ACC oxidase (GACO1, GACO2, GACO3) were isolated from geranium pistils. Transcripts hybridizing with these probes increased slightly in response to self-pollination, but the degree of accumulation in response to various treatments did not correlate with ethylene production. When calculated on a per-plant-part basis, transcripts hybridizing with GACS2 were equally distributed among the stigma+style, sterile ovary, and ovary tissues, but transcripts hybridizing with the three ACC oxidase clones were differentially distributed. All transcripts were differentially expressed among the other tissues of the plant, with GACO1 being the most widely distributed. Ethylene production in geranium pistils was not autocatalytic. Propylene failed to induce ethylene production and ethylene did not induce the accumulation of ACC synthase or ACC oxidase transcripts. ACC accumulated in the stigma and style, and to a smaller extent in the sterile ovary, after pollination. These data support a model of pollination-induced ethylene production by post-transcriptional regulation of ethylene biosynthetic gene expression.
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Affiliation(s)
- D G Clark
- Department of Horticulture, Penn State University, University Park 16802, USA
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