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Goldental-Cohen S, Burstein C, Biton I, Ben Sasson S, Sadeh A, Many Y, Doron-Faigenboim A, Zemach H, Mugira Y, Schneider D, Birger R, Meir S, Philosoph-Hadas S, Irihomovitch V, Lavee S, Avidan B, Ben-Ari G. Ethephon induced oxidative stress in the olive leaf abscission zone enables development of a selective abscission compound. BMC Plant Biol 2017; 17:87. [PMID: 28511694 PMCID: PMC5434568 DOI: 10.1186/s12870-017-1035-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 05/10/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND Table olives (Olea europaea L.), despite their widespread production, are still harvested manually. The low efficiency of manual harvesting and the rising costs of labor have reduced the profitability of this crop. A selective abscission treatment, inducing abscission of fruits but not leaves, is crucial for the adoption of mechanical harvesting of table olives. In the present work we studied the anatomical and molecular differences between the three abscission zones (AZs) of olive fruits and leaves. RESULTS The fruit abscission zone 3 (FAZ3), located between the fruit and the pedicel, was found to be the active AZ in mature fruits and is sensitive to ethephon, whereas FAZ2, between the pedicel and the rachis, is the flower active AZ as well as functioning as the most ethephon induced fruit AZ. We found anatomical differences between the leaf AZ (LAZ) and the two FAZs. Unlike the FAZs, the LAZ is characterized by small cells with less pectin compared to neighboring cells. In an attempt to differentiate between the fruit and leaf AZs, we examined the effect of treating olive-bearing trees with ethephon, an ethylene-releasing compound, with or without antioxidants, on the detachment force (DF) of fruits and leaves 5 days after the treatment. Ethephon treatment enhanced pectinase activity and reduced DF in all the three olive AZs. A transcriptomic analysis of the three olive AZs after ethephon treatment revealed induction of several genes encoding for hormones (ethylene, auxin and ABA), as well as for several cell wall degrading enzymes. However, up-regulation of cellulase genes was found only in the LAZ. Many genes involved in oxidative stress were induced by the ethephon treatment in the LAZ alone. In addition, we found that reactive oxygen species (ROS) mediated abscission in response to ethephon only in leaves. Thus, adding antioxidants such as ascorbic acid or butyric acid to the ethephon inhibited leaf abscission but enhanced fruit abscission. CONCLUSION Our findings suggest that treating olive-bearing trees with a combination of ethephon and antioxidants reduces the detachment force (DF) of fruit without weakening that of the leaves. Hence, this selective abscission treatment may be used in turn to promote mechanized harvest of olives.
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Affiliation(s)
- S. Goldental-Cohen
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - C. Burstein
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - I. Biton
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - S. Ben Sasson
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - A. Sadeh
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - Y. Many
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - A. Doron-Faigenboim
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - H. Zemach
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - Y. Mugira
- The Agricultural Extension Service of Israel, Bet-Dagan, Israel
| | - D. Schneider
- Migal – Galilee Technology Center, P.O. Box 831, 11016 Kiryat Shemona, Israel
| | - R. Birger
- Agriculture Valley Center, P.O. Box 73, 23100 Migdal Haemeq, Israel
| | - S. Meir
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - S. Philosoph-Hadas
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - V. Irihomovitch
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - S. Lavee
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - B. Avidan
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
| | - G. Ben-Ari
- Institute of Plant Sciences, ARO, The Volcani Center, 7528809 Rishon LeZion, Israel
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Meir S, Kochanek B, Glick A, Salim S, Lers A, Burd S, Philosoph-Hadas S, Weiss D. REDUCED PETAL PIGMENTATION IN LISIANTHUS (EUSTOMA GRANDIFLORUM) FLOWERS UNDER LOW LIGHT CONDITIONS IS ASSOCIATED WITH DECREASED EXPRESSION OF ANTHOCYANIN BIOSYNTHESIS GENES. ACTA ACUST UNITED AC 2010. [DOI: 10.17660/actahortic.2010.877.238] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Philosoph-Hadas S, Friedman H, Meir S, Berkovitz-SimanTov R, Rosenberger I, Halevy AH, Kaufman PB, Balk P, Woltering EJ. Gravitropism in cut flower stalks of snapdragon. Adv Space Res 2001; 27:921-932. [PMID: 11596635 DOI: 10.1016/s0273-1177(01)00156-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The negative gravitropic response of cut flower stalks is a complex multistep process that requires the participation of various cellular components acting in succession or in parallel. The process was particularly characterized in snapdragon (Antirrhinum majus L.) spikes with regard to (1) gravity stimulus perception associated with amyloplast reorientation; (2) stimulus transduction mediated through differential changes in the level, action and related genes of auxin and ethylene and their possible interaction; (3) stimulus response associated with differential growth leading to stalk curvature; (4) involvement of cytosolic calcium and actin cytoskeleton. Results show that the gravity-induced amyloplast reorientation, differential over-expression of two early auxin responsive genes and asymmetrical distribution of free IAA are early events in the bending process. These precede the asymmetrical ethylene production and differential stem growth, which was derived from initial shrinkage of the upper stem side and a subsequent elongation of the lower stem side. Results obtained with various calcium- and cytoskeleton-related agents indicate that cytosolic calcium and actin filaments may play essential roles in gravitropism-related processes of cut flower stalks. Therefore, modulators of these two physiological mediators may serve as means for controlling any undesired gravitropic bending.
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Affiliation(s)
- S Philosoph-Hadas
- Dept. of Postharvest Science of Fresh Produce, ARO, The Volcani Center, Bet-Dagan 50250, Israel
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Friedman H, Meir S, Rosenberger I, Halevy AH, Kaufman PB, Philosoph-Hadas S. Inhibition of the gravitropic response of snapdragon spikes by the calcium-channel blocker lanthanum chloride. Plant Physiol 1998; 118:483-92. [PMID: 9765533 PMCID: PMC34823 DOI: 10.1104/pp.118.2.483] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/1998] [Accepted: 06/11/1998] [Indexed: 05/20/2023]
Abstract
The putative Ca(2+)-channel blocker LaCl3 prevented the gravitropic bending of cut snapdragon (Antirrhinum majus L.) spikes (S. Philosoph-Hadas, S. Meir, I. Rosenberger, A.H. Halevy [1996] Plant Physiol 110: 301-310) and inhibited stem curvature to a greater extent than vertical and horizontal stem elongation at the bending zone. This might indicate that LaCl3, which modulates cytosolic Ca2+, does not influence general stem-growth processes but may specifically affect other gravity-associated processes occurring at the stem-bending zone. Two such specific gravity-dependent events were found to occur in the bending zone of snapdragon spikes: sedimentation of starch-containing chloroplasts at the bottom of stem cortex cells, as seen in cross-sections, and establishment of an ethylene gradient across the stem. Our results show that the lateral sedimentation of chloroplasts associated with gravity sensing was prevented in cross-sections taken from the bending zone of LaCl3-treated and subsequently gravistimulated spikes and that LaCl3 completely prevented the gravity-induced, asymmetric ethylene production established across the stem-bending zone. These data indicate that LaCl3 inhibits stem curvature of snapdragon spikes by preventing several gravity-dependent processes. Therefore, we propose that the gravitropic response of shoots could be mediated through a Ca(2+)-dependent pathway involving modulation of cytosolic Ca2+ at various stages.
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Affiliation(s)
- H Friedman
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Bet Dagan, Israel
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Huang FY, Philosoph-Hadas S, Meir S, Callaham DA, Sabato R, Zelcer A, Hepler PK. Increases in Cytosolic Ca2+ in Parsley Mesophyll Cells Correlate with Leaf Senescence. Plant Physiol 1997; 115:51-60. [PMID: 12223791 PMCID: PMC158459 DOI: 10.1104/pp.115.1.51] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The ability to maintain the cytoplasmic Ca2+ concentration ([Ca2+]cyt) at homeostatic levels has been examined during leaf senescence in detached parsley (Petroselinum crispum) leaves. Fluorescence ratiometric imaging of mesophyll cells isolated from parsley leaves at various senescence stages and loaded with the Ca2+ indicator fura-2 has revealed a distinct elevation of [Ca2+]cyt, which was positively correlated with the progress of leaf senescence. This initial increase of [Ca2+]cyt, which was first observed in cells isolated from 3-d-senescent leaves, occurred 1 d before or in parallel with changes in two established senescence parameters, chlorophyll loss and lipid peroxidation. However, the [Ca2+]cyt elevation followed by 2 d the initial increase in the senescence-associated proteolysis. Whereas the [Ca2+]cyt of nonsenescent cells remained at the basal level, the elevated [Ca2+]cyt of the senescent cells was a long-lasting effect. Experimental retardation of senescence processes, achieved by pretreatment of detached leaves with the cytokinin benzyladenine, resulted in maintenance of homeostatic levels of [Ca2+]cyt in cells isolated from 3-d-senescent leaves. These observations demonstrate for the first time to our knowledge a correlation between elevated [Ca2+]cyt and the process of senescence in parsley leaves. Such senescence-associated elevation of [Ca2+]cyt, which presumably results from a loss of the cell's capability to extrude Ca2+, may serve as a signal inducing subsequent deteriorative processes.
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Affiliation(s)
- F. Y. Huang
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, 01003 (F.-Y.H., D.A.C., P.K.H.)
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Philosoph-Hadas S, Meir S, Rosenberger I, Halevy AH. Regulation of the gravitropic response and ethylene biosynthesis in gravistimulated snapdragon spikes by calcium chelators and ethylene inhibitors. Plant Physiol 1996; 110:301-10. [PMID: 11536726 PMCID: PMC157721 DOI: 10.1104/pp.110.1.301] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The possible involvement of Ca2+ as a second messenger in snapdragon (Antirrhinum majus L.) shoot gravitropism, as well as the role of ethylene in this bending response, were analyzed in terms of stem curvature and gravity-induced asymmetric ethylene production rates, ethylene-related metabolites, and invertase activity across the stem. Application of Ca2+ chelators (ethylenediaminetetraacetic acid, trans-1,2-cyclohexane dinitro-N,N,N',N'-tetraacetic acid, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N',-tetraacetic acid) or a Ca2+ antagonist (LaCl3) to the spikes caused a significant loss of their gravitropic response following horizontal placement. Conversely, the Ca2+ ionophore A23187 or the agonist Bay K-8644 increased gravibending. Longitudinally halved stem sections had significantly higher amounts of ethylene, 1-aminocyclopropane-1-carboxylic acid, and 1-(malonylamino) cyclopropane-1-carboxylic acid compared with vertical controls, with the extra production arising exclusively from the lower half of the stem. trans-1,2-cyclohexane dinitro-N,N,N',N'-tetraacetic acid pretreatment completely abolished the gravity-induced ethylene gradient across the stem, thereby leading to a significant reduction of the curvature. Similarly, reduction of the ethylene produced in the gravistimulated with CoCl2 or inhibition of its action by silver thiosulfate or 2,5-norbornadiene significantly inhibited the subsequent gravibending. Silver thiosulfate and CoCl2 also abolished the gravity-induced gradient of invertase activity across the stem, which is associated with the asymmetric stem elongation. These results suggest that cytosolic Ca2+ may regulate auxin action in snapdragon spikes, manifested as increased ethylene production, which is, in turn, intimately correlated with stem bending. Therefore, both hormones seem to play significant roles in induction and progress of the gravibending of snapdragon spikes.
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Affiliation(s)
- S Philosoph-Hadas
- Department of Postharvest Science of Fresh Produce, The Volcani Center, Bet Dagan, Israel.
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Philosoph-Hadas S, Meir S, Rosenberger I, Halevy A. CONTROL AND REGULATION OF THE GRAVITROPIC RESPONSE OF CUT FLOWERING STEMS DURING STORAGE AND HORIZONTAL TRANSPORT. ACTA ACUST UNITED AC 1995. [DOI: 10.17660/actahortic.1995.405.44] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Meir S, Reuveni Y, Rosenberger I, Davidson H, Philosoph-Hadas S. IMPROVEMENT OF THE POSTHARVEST KEEPING QUALITY OF CUT FLOWERS AND CUTTINGS BY APPLICATION OF WATER-SOLUBLE ANTIOXIDANTS. ACTA ACUST UNITED AC 1994. [DOI: 10.17660/actahortic.1994.368.44] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Meir S, Riov J, Philosoph-Hadas S, Aharoni N. Carbohydrates Stimulate Ethylene Production in Tobacco Leaf Discs : III. Stimulation of Enzymic Hydrolysis of Indole-3-Acetyl-l-Alanine. Plant Physiol 1989; 90:1246-8. [PMID: 16666915 PMCID: PMC1061875 DOI: 10.1104/pp.90.4.1246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The sucrose-stimulated in vivo hydrolysis of indole-3-acetyl-l-alanine (IAAIa) in tobacco (Nicotiana tabacum L.) leaf discs was confirmed by in vitro analysis of an IAAIa-hydrolyzing enzyme isolated from the same tissue. The enzymic activity could be stimulated by either aging of the tissue or by application of external IAA or sucrose. A combination of the above three treatments yielded maximal activity.
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Affiliation(s)
- S Meir
- Department of Fruit and Vegetable Storage, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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Philosoph-Hadas S, Aharoni N. Galactose inhibits the conversion of 1-aminocyclopropane-1-carboxylic Acid to ethylene in aged tobacco leaf discs. Plant Physiol 1987; 83:8-11. [PMID: 16665220 PMCID: PMC1056289 DOI: 10.1104/pp.83.1.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
d-Galactose has been shown to have toxic and growth inhibitory effects in plants. When applied at levels of 50 millimolar to tobacco (Nicotiana tabacum L. cv Xanthi) leaf discs galactose caused a rapid increase in ethylene production during the first 2 days of incubation, followed by a rapid return to the basal level on the third day. This pattern of galactose-stimulated ethylene production was accompanied by increased formation of 1-aminocyclopropane-1-carboxylic acid (ACC), which accumulated without being metabolized to ethylene or to the ACC-conjugate. The inhibitory effect of galactose (50 millimolar) on the conversion of ACC of ethylene was relieved partially by d-glucose or sucrose (50 millimolar), and completely by CO(2) (10%), which were shown to enhance this conversion by themselves. Consequently, application of galactose plus any one of these compounds increased ethylene production and decreased free ACC levels. The data suggest that galactose toxicity may result in both an increased ethylene production as well as in accumulation of free ACC in aged discs. The increased ethylene production rates and ACC levels may, in turn, play a role in the development of symptoms associated with galactose toxicity.
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Affiliation(s)
- S Philosoph-Hadas
- Department of Fruit and Vegetable Storage, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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Philosoph-Hadas S, Aharoni N, Yang SF. Carbon dioxide enhances the development of the ethylene forming enzyme in tobacco leaf discs. Plant Physiol 1986; 82:925-9. [PMID: 16665167 PMCID: PMC1056234 DOI: 10.1104/pp.82.4.925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Since CO(2) is known to stimulate ethylene production by promoting the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, the effect of CO(2) on the activity and the development of the ethylene forming enzyme (EFE) was studied in tobacco (Nicotiana tabacum L. cv Havana 425 and Xanthi) leaf discs. In addition to previous observations that EFE activity is dependent on CO(2) concentration and is saturable with 2% CO(2), present data show two saturation curves at 2% and 10% CO(2). Promotion of EFE development was dependent also on CO(2) concentration (saturated at 2% CO(2)) and duration (maximum at 24 in the dark), and was abolished by 20 micromolar cycloheximide. Application of exogenous ethylene (20 microliters per liter) or light treatment further increased the CO(2)-enhanced development of EFE, implying that these two factors can also affect EFE development via interaction with CO(2). The results suggest that CO(2) exerts its stimulatory effect on the conversion of ACC to ethylene by enhancing not only the activity but also the synthesis of EFE in leaf discs.
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Affiliation(s)
- S Philosoph-Hadas
- Department of Vegetable Crops, University of California, Davis, California 95616
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Jiao XZ, Philosoph-Hadas S, Su LY, Yang SF. The Conversion of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid to 1-Aminocyclopropane-1-Carboxylic Acid in Plant Tissues. Plant Physiol 1986; 81:637-41. [PMID: 16664869 PMCID: PMC1075390 DOI: 10.1104/pp.81.2.637] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Since 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the major conjugate of 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues, is a poor ethylene producer, it is generally thought that MACC is a biologically inactive end product of ACC. In the present study we have shown that the capability of watercress (Nasturtium officinale R. Br) stem sections and tobacco (Nicotiana tabacum L.) leaf discs to convert exogenously applied MACC to ACC increased with increasing MACC concentrations (0.2-5 millimolar) and duration (4-48 hours) of the treatment. The MACC-induced ethylene production was inhibited by CoCl(2) but not by aminoethoxyvinylglycin, suggesting that the ACC formed is derived from the MACC applied, and not from the methionine pathway. This was further confirmed by the observation that radioactive MACC released radioactive ACC and ethylene. A cell-free extract, which catalyzes the conversion of MACC to ACC, was prepared from watercress stems which were preincubated with 1 millimolar MACC for 24 hours. Neither fresh tissues nor aged tissues incubated without external MACC exhibited enzymic activity, confirming the view that the enzyme is induced by MACC. The enzyme had a K(m) of 0.45 millimolar for MACC and showed maximal activity at pH 8.0 in the presence of 1 millimolar MnSO(4). The present study indicates that high MACC levels in the plant tissue can induce to some extent the capability to convert MACC to ACC.
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Affiliation(s)
- X Z Jiao
- Department of Vegetable Crops, University of California, Davis, California 95616
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Meir S, Philosoph-Hadas S, Epstein E, Aharoni N. Carbohydrates stimulate ethylene production in tobacco leaf discs : I. Interaction with auxin and the relation to auxin metabolism. Plant Physiol 1985; 78:131-8. [PMID: 16664185 PMCID: PMC1064690 DOI: 10.1104/pp.78.1.131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Various naturally occurring carbohydrates, applied at a concentration range of 1 to 100 mm, stimulated ethylene production for several days in indoleacetic acid (IAA)-treated or untreated tobacco (Nicotiana tabacum L. cv ;Xanthi') leaf discs. The lag period for this sugar-stimulated ethylene production was 8 to 12 hours after excision in the untreated leaf discs, but less than 2 hours in the IAA-treated ones. Among the tested carbohydrates, 12 were found to increase synergistically ethylene production, with d-galactose, sucrose, and lactose being the most active; mannitol and l-glucose had no effect. The extent and duration of the increased ethylene production was dependent upon the type of sugar applied, the tissue's age, and the existence of both exogenous IAA and sugar in the medium. Sucrose appeared to elicit a continuous IAA effect for 48 hours, as expressed by increased ethylene production, even when IAA was removed from the medium after a 4-hour pulse. Sucrose stimulated both the uptake and decarboxylation of [1-(14)C]IAA, as well as the hydrolysis of the esteric and amide IAA conjugates formed in the tissue after application of free IAA. This gradual hydrolysis was accompanied by a further accumulation of a third IAA metabolite. Moreover, synthetic indole-3-acetyl-l-alanine increased ethylene production mainly with sucrose, and this effect was accompanied by its increased decarboxylation and turnover pattern suggesting that release of free IAA was involved. An esteric IAA conjugate, tentatively identified by GC retention time was found to be the major component (84%) of the naturally occurring IAA conjugates in tobacco leaves. Accordingly the sucrose-stimulated ethylene production in tobacco leaves can be ascribed mainly to the sucrose-stimulated hydrolysis of the esteric IAA conjugate.
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Affiliation(s)
- S Meir
- Department of Fruit and Vegetable Storage, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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Philosoph-Hadas S, Meir S, Aharoni N. Carbohydrates Stimulate Ethylene Production in Tobacco Leaf Discs : II. Sites of Stimulation in the Ethylene Biosynthesis Pathway. Plant Physiol 1985; 78:139-43. [PMID: 16664186 PMCID: PMC1064691 DOI: 10.1104/pp.78.1.139] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Galactose, sucrose, and glucose (50 millimolar) applied to tobacco leaf discs (Nicotiana tabacum L. cv ;Xanthi') during a prolonged incubation (5-6 d) markedly stimulated ethylene production which, in turn, could be inhibited by aminoethoxyvinylglycine (2-amino-4-(2'-aminoethoxy)-trans-3-butenoic acid) (AVG) or Co(2+) ions. These three tested sugars also stimulated the conversion of l-[3,4-(14)C]methionine to [(14)C]1-amino-cyclopropane-1-carboxylic acid (ACC) and to [(14)C]ethylene, thus indicating that the carbohydrates-stimulated ethylene production proceeds from methionine via the ACC pathway. Sucrose concentrations above 25 mm considerably enhanced ACC-dependent ethylene production, and this enhancement was related to the increased respiratory carbon dioxide. However, sucrose by itself could directly promote the step of ACC conversion to ethylene, since low sucrose concentrations (1-25 mm) enhanced ACC-dependent ethylene production also in the presence of 15% CO(2).The data suggest that the stimulation of ethylene production by sugars in tobacco leaf discs results from enhancement of ACC formation as well as from the conversion of ACC to ethylene, when both steps could be involved in regulation of ethylene biosynthesis.
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Affiliation(s)
- S Philosoph-Hadas
- Department of Fruit and Vegetable Storage, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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