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Ping Leng - One of the best experts on this subject based on the ideXlab platform.
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Expression analysis of the DkNCED1, DkNCED2 and DkCYP707A1 genes that regulate homeostasis of abscisic acid during the maturation of persimmon fruit
Journal of Horticultural Science & Biotechnology, 2020Co-Authors: Shengli Zhao, Yanping Wang, Kai Ji, Jian-xun Qi, Chaorui Duan, Pei Chen, Ping LengAbstract:SummaryTo reveal details of the role(s) of abscisic acid (ABA) during fruit ripening and the regulation of ABA levels, two 9-Cis-Epoxycarotenoid Dioxygenase genes (DkNCED1 and DkNCED2) and the DkCYP707A1 gene for ABA 8'-hydroxylase were isolated from unripened persimmon fruit. Expression of DkNCED1 increased at the start of fruit maturation and peaked 20 d before harvest, which was consistent with the accumulation of ABA during ripening in persimmon. Expression of the DkNCED2 gene was high in fruit at the immature stage, then declined continuously throughout ripening. Compared to the DkNCED genes, expression of DkCYP707A1 peaked 145 d after full-bloom (DAFB), then declined. Ethylene release decreased gradually from 65 DAFB to 115 DAFB, then peaked at 10 d after harvest. Water-deficit stress enhanced the expression of DkNCED1, but down-regulated transcript levels of DkCYP707A1 in the calyx. These results suggest that endogenous ABA content is modulated by a dynamic balance between ABA biosynthesis and cata...
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functional analysis of slnced1 in pistil development and fruit set in tomato solanum lycopersicum l
Scientific Reports, 2019Co-Authors: Ying Fu, Bin Liang, Qian Li, Juan Wang, Ping LengAbstract:Abscisic acid (ABA) is an important regulator of many plant developmental processes, although its regulation in the pistil during anthesis is unclear. We investigated the role of 9-Cis-Epoxycarotenoid Dioxygenase (SlNCED1), a key ABA biosynthesis enzyme, through overexpression and transcriptome analysis in the tomato pistil. During pistil development, ABA accumulates and SlNCED1 expression increases continually, peaking one day before full bloom, when the maximum amount of ethylene is released in the pistil. ABA accumulation and SlNCED1 expression in the ovary remained high for three days before and after full bloom, but then both declined rapidly four days after full bloom following senescence and petal abscission and expansion of the young fruits. Overexpression of SlNCED1 significantly increased ABA levels and also up-regulated SlPP2C5 expression, which reduced ABA signaling activity. Overexpression of SlNCED1 caused up-regulation of pistil-specific Zinc finger transcription factor genes SlC3H29, SlC3H66, and SlC3HC4, which may have affected the expression of SlNCED1-mediated pistil development-related genes, causing major changes in ovary development. Increased ABA levels are due to SlNCED1 overexpresson which caused a hormonal imbalance resulting in the growth of parthenocarpic fruit. Our results indicate that SlNCED1 plays a crucial role in the regulation of ovary/pistil development and fruit set.
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Role of abscisic acid in regulating fruit set and ripening in squash (Cucurbita pepo L.)
New Zealand Journal of Crop and Horticultural Science, 2016Co-Authors: Pengfei Chen, Bin Liang, Yushu Zhang, Xiawan Zhai, Suihuan He, Ping LengAbstract:ABSTRACTSquash is a non-climacteric fruit, so the release of ethylene plays a limited role in the ripening process; however, there is a large accumulation of abscisic acid (ABA) during fruit maturation and ripening. To investigate the contribution of ABA in squash fruit development, the CpNCED1 gene, which encodes the key enzyme in ABA biosynthesis (9-Cis-Epoxycarotenoid Dioxygenase [NCED]), was cloned from squash fruit, and its transcriptional regulation during fruit development, dehydration and pollination was analysed using a quantitative reverse transcription polymerase chain reaction (qRT-PCR). The expression of CpNCED1 peaked 20 days after full bloom (DAFB) in the pulp and seed, and 25 DAFB in the peel, all of which corresponded with the accumulation of ABA. The application of exogenous ABA increased the expression of CpNCED1 and the release of ethylene, thereby promoting fruit ripening. The expression of CpNCED1 was also induced by dehydration stress and pollination. These findings show that ABA pl...
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Fruit-specific RNAi-mediated suppression of SlNCED1 increases both lycopene and β-carotene contents in tomato fruit
Journal of Experimental Botany, 2012Co-Authors: Bing Yuan, Mei Zhang, Ling Wang, Qi Wang, Ping LengAbstract:Abscisic acid (ABA) plays important roles during tomato fruit ripening. To study the regulation of carotenoid biosynthesis by ABA, the SlNCED1 gene encoding 9-Cis-Epoxycarotenoid Dioxygenase (NCED), a key enzyme in the ABA biosynthesis, was suppressed in tomato plants by transformation with an RNA interference (RNAi) construct driven by a fruit-specific E8 promoter. ABA accumulation and SlNCED1 transcript levels in the transgenic fruit were down-regulated to between 20–50% of that in control fruit. This significant reduction in NCED activity led to the carbon that normally channels to free ABA as well as the ABA metabolite accumulation during ripening to be partially blocked. Therefore, this ‘backlogged’ carbon transformed into the carotenoid pathway in the RNAi lines resulted in increased assimilation and accumulation of upstream compounds in the pathway, chiefly lycopene and β-carotene. Fruit of all RNAi lines displayed deep red coloration compared with the pink colour of control fruit. The decrease in endogenous ABA in these transgenics resulted in an increase in ethylene, by increasing the transcription of genes related to the synthesis of ethylene during ripening. In conclusion, ABA potentially regulated the degree of pigmentation and carotenoid composition during ripening and could control, at least in part, ethylene production and action in climacteric tomato fruit.
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Role of abscisic acid and ethylene in sweet cherry fruit maturation: molecular aspects
New Zealand Journal of Crop and Horticultural Science, 2011Co-Authors: Pengfei Chen, Kai Ji, Ping Li, Qian Li, Ya Wang, Ping LengAbstract:To investigate the role of abscisic acid (ABA) and ethylene in the maturation of sweet cherry fruit, cloning was carried out on one cDNA (PacNCED1) encoding 9-Cis-Epoxycarotenoid Dioxygenase (NCED)—a key enzyme in ABA biosynthesis—and on one cDNA (PacACO1) encoding 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase—an enzyme involved in ethylene biosynthesis. A BLAST homology search revealed that the sequences of DNA and amino acids in both PacNCED1 and PacACO1 showed a high degree of homology to comparable molecules of other plant species. The expression of PacNCED1 increased at the beginning of maturation and peaked 4 days before harvest, which was consistent with ABA accumulation during cherry ripening. Application of exogenous ABA increased the ABA content, inducing the expression of PacNCED1, and promoted ripening via enhancing colour formation and sugar accumulation. The expression of PacACO1 was not observed, and ethylene production was below detection levels, during the entire process of fruit de...
Suzanne R Abrams - One of the best experts on this subject based on the ideXlab platform.
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Sesquiterpene-like inhibitors of a 9-Cis-Epoxycarotenoid Dioxygenase regulating abscisic acid biosynthesis in higher plants
Bioorganic and Medicinal Chemistry, 2009Co-Authors: Jason Boyd, Yuanzhu Gai, Ken M. Nelson, Erica Lukiwski, James Talbot, Stacey Owen, L. Irina Zaharia, Adrian J. Cutler, Mary K. Loewen, Suzanne R AbramsAbstract:Abscisic acid (ABA) is a carotenoid-derived plant hormone known to regulate critical functions in growth, development and responses to environmental stress. The key enzyme which carries out the first committed step in ABA biosynthesis is the carotenoid cleavage 9-Cis-Epoxycarotenoid Dioxygenase (NCED). We have developed a series of sulfur and nitrogen-containing compounds as potential ABA biosynthesis inhibitors of the NCED, based on modification of the sesquiterpenoid segment of the 9-cis-xanthophyll substrates and product. In in vitro assays, three sesquiterpene-like carotenoid cleavage Dioxygenase (SLCCD) inhibitor compounds 13, 17 and 18 were found to act as inhibitors of Arabidopsis thaliana NCED 3 (AtNCED3) with Ki′s of 93, 57 and 87 μM, respectively. Computational docking to a model of AtNCED3 supports a mechanism of inhibition through coordination of the heteroatom with the non-heme iron in the enzyme active site. In pilot studies, pretreatment of osmotically stressed Arabidopsis plants with compound 13 resulted lower levels of ABA and catabolite accumulation compared to levels in mannitol-stressed plant controls. This same inhibitor moderated known ABA-induced gene regulation effects and was only weakly active in inhibition of seed germination. Interestingly, all three inhibitors led to moderation of the stress-induced transcription of AtNCED3 itself, which could further contribute to lowering ABA biosynthesis in planta. Overall, these sesquiterpenoid-like inhibitors present new tools for controlling and investigating ABA biosynthesis and regulation. Crown Copyright © 2009.
Kazuo Shinozaki - One of the best experts on this subject based on the ideXlab platform.
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N-Benzylideneaniline and N-Benzylaniline are Potent Inhibitors of Lignostilbene-α,β-Dioxygenase, a Key Enzyme in Oxidative Cleavage of the Central Double Bond of Lignostilbene
Journal of Enzyme Inhibition and Medicinal Chemistry, 2020Co-Authors: Hiroki Inoue, Masatomo Kobayashi, Kazuo Shinozaki, Tamio Saito, Katsuhiko Sekimata, Tamami Terada, Shigehiro Kamoda, Yoshimasa Saburi, Shigeo YoshidaAbstract:Lignostilbene-α,β-Dioxygenase (LSD, EC 1.13.11.43) is involved in oxidative cleavage of the central double bond of lignostilbene to form the corresponding aldehydes by a mechanism similar to those of 9-Cis-Epoxycarotenoid Dioxygenase and β-carotene 15,15′-Dioxygenase, key enzymes in abscisic acid biosynthesis and vitamin A biosynthesis, respectively. In this study, several N-benzylideneanilines and amine were synthesized and examined for their efficacy as inhibitors of LSD. N-(4-Hydroxybenzylidene)-3-methoxyaniline was found to be a potent inhibitor with IC50 = 0.3 µM and N-(4-hydroxybenzyl)-3-methoxyaniline was also active with IC50 = 10 µM. The information obtained from the structure-activity relationships study here can aid in discovering inhibitors of both abscisic acid and vitamin A biosynthesis.
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Characterization of the promoter region of an Arabidopsis gene for 9-Cis-Epoxycarotenoid Dioxygenase involved in dehydration-inducible transcription.
DNA Research, 2013Co-Authors: Babak Behnam, Satoshi Iuchi, Masatomo Kobayashi, Kazuko Yamaguchi-shinozaki, Miki Fujita, Yasunari Fujita, Hironori Takasaki, Yuriko Osakabe, Kazuo ShinozakiAbstract:Plants respond to dehydration stress and tolerate water-deficit status through complex physiological and cellular processes. Many genes are induced by water deficit. Abscisic acid (ABA) plays important roles in tolerance to dehydration stress by inducing many stress genes. ABA is synthesized de novo in response to dehydration. Most of the genes involved in ABA biosynthesis have been identified, and they are expressed mainly in leaf vascular tissues. Of the products of such genes, 9-Cis-Epoxycarotenoid Dioxygenase (NCED) is a key enzyme in ABA biosynthesis. One of the five NCED genes in Arabidopsis, AtNCED3, is significantly induced by dehydration. To understand the regulatory mechanism of the early stages of the dehydration stress response, it is important to analyse the transcriptional regulatory systems of AtNCED3. In the present study, we found that an overlapping G-box recognition sequence (5′-CACGTG-3′) at −2248 bp from the transcriptional start site of AtNCED3 is an important cis-acting element in the induction of the dehydration response. We discuss the possible transcriptional regulatory system of dehydration-responsive AtNCED3 expression, and how this may control the level of ABA under water-deficit conditions.
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Drought Induction of Arabidopsis 9-Cis-Epoxycarotenoid Dioxygenase Occurs in Vascular Parenchyma Cells
Plant Physiology, 2008Co-Authors: Akira Endo, Yoshiaki Sawada, Hirokazu Takahashi, Masanori Okamoto, Keiichi Ikegami, Hanae Koiwai, Tomonobu Toyomasu, Wataru Mitsuhashi, Kazuo ShinozakiAbstract:The regulation of abscisic acid (ABA) biosynthesis is essential for plant responses to drought stress. In this study, we examined the tissue-specific localization of ABA biosynthetic enzymes in turgid and dehydrated Arabidopsis (Arabidopsis thaliana) plants using specific antibodies against 9-Cis-Epoxycarotenoid Dioxygenase 3 (AtNCED3), AtABA2, and Arabidopsis aldehyde oxidase 3 (AAO3). Immunohistochemical analysis revealed that in turgid plants, AtABA2 and AAO3 proteins were localized in vascular parenchyma cells most abundantly at the boundary between xylem and phloem bundles, but the AtNCED3 protein was undetectable in these tissues. In water-stressed plants, AtNCED3 was detected exclusively in the vascular parenchyma cells together with AtABA2 and AAO3. In situ hybridization using the antisense probe for AtNCED3 showed that the drought-induced expression of AtNCED3 was also restricted to the vascular tissues. Expression analysis of laser-microdissected cells revealed that, among nine drought-inducible genes examined, the early induction of most genes was spatially restricted to vascular cells at 1 h and then some spread to mesophyll cells at 3 h. The spatial constraint of AtNCED3 expression in vascular tissues provides a novel insight into plant systemic response to drought stresses.
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A 9-Cis-Epoxycarotenoid Dioxygenase inhibitor for use in the elucidation of abscisic acid action mechanisms
Bioorganic & Medicinal Chemistry, 2006Co-Authors: Nobutaka Kitahata, Masatomo Kobayashi, Kazuo Shinozaki, Tamio Saito, Shigeo Yoshida, Natsumi Noji, Takeshi Nakano, Kazuyuki Kuchitsu, Shogo MatsumotoAbstract:Abstract The plant hormone abscisic acid (ABA) accumulates in response to drought stress and confers stress tolerance to plants. 9- cis -Epoxycarotenoid Dioxygenase (NCED), the key regulatory enzyme in the ABA biosynthesis pathway, plays an important role in ABA accumulation. Treatment of plants with abamine, the first NCED inhibitor identified, inhibits ABA accumulation. On the basis of structure–activity relationship studies of abamine, we identified an inhibitor of ABA accumulation more potent than abamine and named it abamineSG. An important structural feature of abamineSG is a three-carbon linker between the methyl ester and the nitrogen atom. Treatment of osmotically stressed plants with 100 μM abamineSG inhibited ABA accumulation by 77% as compared to the control, whereas abamine inhibited the accumulation by 35%. The expression of AB A-responsive genes and ABA catabolic genes was strongly inhibited in abamineSG-treated plants under osmotic stress. AbamineSG is a competitive inhibitor of the enzyme NCED, with a K i of 18.5 μM. Although the growth of Arabidopsis seedlings was inhibited by abamine at high concentrations (>50 μM), an effect that was unrelated to the inhibition of ABA biosynthesis, seedling growth was not affected by 100 μM abamineSG. These results suggest that abamineSG is a more potent and specific inhibitor of ABA biosynthesis than abamine.
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A Novel Inhibitor of 9-Cis-Epoxycarotenoid Dioxygenase in Abscisic Acid Biosynthesis in Higher Plants
Plant Physiology, 2004Co-Authors: Nobutaka Kitahata, Masatomo Kobayashi, Kazuko Yamaguchi-shinozaki, Kazuo Shinozaki, Tamio Saito, Shigeo Yoshida, Katsuhiko Sekimata, Kazuo Nakashima, Tadao AsamiAbstract:Abscisic acid (ABA) is a major regulator in the adaptation of plants to environmental stresses, plant growth, and development. In higher plants, the ABA biosynthesis pathway involves the oxidative cleavage of 9-Cis-Epoxycarotenoids, which may be the key regulatory step in the pathway catalyzed by 9-Cis-Epoxycarotenoid Dioxygenase (NCED). We developed a new inhibitor of ABA biosynthesis targeting NCED and named it abamine (ABA biosynthesis inhibitor with an amine moiety). Abamine is a competitive inhibitor of NCED, with a Ki of 38.8 μm. In 0.4 m mannitol solution, which mimics the effects of osmotic stress, abamine both inhibited stomatal closure in spinach (Spinacia oleracea) leaves, which was restored by coapplication of ABA, and increased luminescence intensity in transgenic Arabidopsis containing the RD29B promoter-luciferase fusion. The ABA content of plants in 0.4 m mannitol was increased approximately 16-fold as compared with that of controls, whereas 50 to 100 μm abamine inhibited about 50% of this ABA accumulation in both spinach leaves and Arabidopsis. Abamine-treated Arabidopsis was more sensitive to drought stress and showed a significant decrease in drought tolerance than untreated Arabidopsis. These results suggest that abamine is a novel ABA biosynthesis inhibitor that targets the enzyme catalyzing oxidative cleavage of 9-Cis-Epoxycarotenoids. To test the effect of abamine on plants other than Arabidopsis, it was applied to cress (Lepidium sativum) plants. Abamine enhanced radicle elongation in cress seeds, which could be due to a decrease in the ABA content of abamine-treated plants. Thus, it is possible to think that abamine should enable us to elucidate the functions of ABA in cells or plants and to find new mutants involved in ABA signaling.
Adrian J. Cutler - One of the best experts on this subject based on the ideXlab platform.
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Sesquiterpene-like inhibitors of a 9-Cis-Epoxycarotenoid Dioxygenase regulating abscisic acid biosynthesis in higher plants
Bioorganic and Medicinal Chemistry, 2009Co-Authors: Jason Boyd, Yuanzhu Gai, Ken M. Nelson, Erica Lukiwski, James Talbot, Stacey Owen, L. Irina Zaharia, Adrian J. Cutler, Mary K. Loewen, Suzanne R AbramsAbstract:Abscisic acid (ABA) is a carotenoid-derived plant hormone known to regulate critical functions in growth, development and responses to environmental stress. The key enzyme which carries out the first committed step in ABA biosynthesis is the carotenoid cleavage 9-Cis-Epoxycarotenoid Dioxygenase (NCED). We have developed a series of sulfur and nitrogen-containing compounds as potential ABA biosynthesis inhibitors of the NCED, based on modification of the sesquiterpenoid segment of the 9-cis-xanthophyll substrates and product. In in vitro assays, three sesquiterpene-like carotenoid cleavage Dioxygenase (SLCCD) inhibitor compounds 13, 17 and 18 were found to act as inhibitors of Arabidopsis thaliana NCED 3 (AtNCED3) with Ki′s of 93, 57 and 87 μM, respectively. Computational docking to a model of AtNCED3 supports a mechanism of inhibition through coordination of the heteroatom with the non-heme iron in the enzyme active site. In pilot studies, pretreatment of osmotically stressed Arabidopsis plants with compound 13 resulted lower levels of ABA and catabolite accumulation compared to levels in mannitol-stressed plant controls. This same inhibitor moderated known ABA-induced gene regulation effects and was only weakly active in inhibition of seed germination. Interestingly, all three inhibitors led to moderation of the stress-induced transcription of AtNCED3 itself, which could further contribute to lowering ABA biosynthesis in planta. Overall, these sesquiterpenoid-like inhibitors present new tools for controlling and investigating ABA biosynthesis and regulation. Crown Copyright © 2009.
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Formation and breakdown of ABA
Trends in Plant Science, 1999Co-Authors: Adrian J. Cutler, Joan E. KrochkoAbstract:The phytohormone, abscisic acid (ABA) is found in all photosynthetic organisms. The amount of ABA present is determined by the dynamic balance between biosynthesis and degradation: these two processes are influenced by development, environmental factors such as light and water stress, and other growth regulators. ABA is synthesized from a C40carotenoid precursor and the first enzyme committed specifically to ABA synthesis is a plastid-localized 9-Cis-Epoxycarotenoid Dioxygenase, which cleaves an epoxycarotenoid precursor to form xanthoxin. Subsequently, xanthoxin is converted to ABA by two cytosolic enzymes via abscisic aldehyde, but there appears to be at least one minor alternative pathway. The major catabolic route leads to 8'-hydroxy ABA and phaseic acid formation, catalyzed by the cytochrome P450 enzyme ABA 8'-hydroxylase. In addition, there are alternate catabolic pathways via conjugation, 4'-reduction and 7'-hydroxylation. As a consequence of recent developments, the mechanism by which the concentration of hormonally active ABA is controlled at the cellular, tissue and whole plant level can now be analyzed in detail.
Andrew J Thompson - One of the best experts on this subject based on the ideXlab platform.
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Does abscisic acid affect strigolactone biosynthesis?
New Phytologist, 2010Co-Authors: Juan Antonio López-Ráez, Anna K. Undas, Francel Verstappen, Martin J. Sergeant, Tatsiana Charnikhova, Andrew J Thompson, Timothy D H Bugg, Peter Mulder, Wouter Kohlen, Carolien Ruyter-spiraAbstract:SUMMARY: *Strigolactones are considered a novel class of plant hormones that, in addition to their endogenous signalling function, are exuded into the rhizosphere acting as a signal to stimulate hyphal branching of arbuscular mycorrhizal (AM) fungi and germination of root parasitic plant seeds. Considering the importance of the strigolactones and their biosynthetic origin (from carotenoids), we investigated the relationship with the plant hormone abscisic acid (ABA). *Strigolactone production and ABA content in the presence of specific inhibitors of oxidative carotenoid cleavage enzymes and in several tomato ABA-deficient mutants were analysed by LC-MS/MS. In addition, the expression of two genes involved in strigolactone biosynthesis was studied. *The carotenoid cleavage Dioxygenase (CCD) inhibitor D2 reduced strigolactone but not ABA content of roots. However, in abamineSG-treated plants, an inhibitor of 9-Cis-Epoxycarotenoid Dioxygenase (NCED), and the ABA mutants notabilis, sitiens and flacca, ABA and strigolactones were greatly reduced. The reduction in strigolactone production correlated with the downregulation of LeCCD7 and LeCCD8 genes in all three mutants. *The results show a correlation between ABA levels and strigolactone production, and suggest a role for ABA in the regulation of strigolactone biosynthesis.
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Abscisic acid biosynthesis in tomato: regulation of zeaxanthin epoxidase and 9-Cis-Epoxycarotenoid Dioxygenase mRNAs by light/dark cycles, water stress and abscisic acid
Plant Molecular Biology, 2000Co-Authors: Andrew J Thompson, Alison C. Jackson, Alan Burbidge, Rachel A. Parker, David R. Morpeth, Ian B. TaylorAbstract:Two genes encoding enzymes in the abscisic acid (ABA) biosynthesis pathway, zeaxanthin epoxidase (ZEP) and 9- cis -epoxycarotenoid Dioxygenase (NCED), have previously been cloned by transposon tagging in Nicotiana plumbaginifolia and maize respectively. We demonstrate that antisense down-regulation of the tomato gene LeZEP1 causes accumulation of zeaxanthin in leaves, suggesting that this gene also encodes ZEP. LeNCED1 is known to encode NCED from characterization of a null mutation ( notabilis ) in tomato. We have used LeZEP1 and LeNCED1 as probes to study gene expression in leaves and roots of whole plants given drought treatments, during light/dark cycles, and during dehydration of detached leaves. During drought stress, NCED mRNA increased in both leaves and roots, whereas ZEP mRNA increased in roots but not leaves. When detached leaves were dehydrated, NCED mRNA responded rapidly to small reductions in water content. Using a detached leaf system with ABA-deficient mutants and ABA feeding, we investigated the possibility that NCED mRNA is regulated by the end product of the pathway, ABA, but found no evidence that this is the case. We also describe strong diurnal expression patterns for both ZEP and NCED, with the two genes displaying distinctly different patterns. ZEP mRNA oscillated with a phase very similar to light-harvesting complex II (LHCII) mRNA, and oscillations continued in a 48 h dark period. NCED mRNA oscillated with a different phase and remained low during a 48 h dark period. Implications for regulation of water stress-induced ABA biosynthesis are discussed.
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Control of abscisic acid synthesis
J.Exp.Bot., 2000Co-Authors: I. B. Taylor, ADAM BURBIDGE, Andrew J ThompsonAbstract:The abscisic acid (ABA) biosynthetic pathway involves the formation of a 9-Cis-Epoxycarotenoid precursor. Oxidative cleavage then results in the formation of xanthoxin, which is subsequently converted to ABA. A number of steps in the pathway may control ABA synthesis, but particular attention has been given to the enzyme involved in the oxidative cleavage reaction, i.e. 9-Cis-Epoxycarotenoid Dioxygenase (NCED). Cloning of a gene encoding this enzyme in maize was first reported in 1997. Mapping and DNA sequencing studies indicated that a wilty tomato mutant was due to a deletion in the gene encoding an enzyme with a very similar amino acid sequence to this maize NCED. The potential use of this gene in altering ABA content will be discussed together with other genes encoding ABA biosynthetic enzymes
