Stress-Induced Factor Involved in Flower Formation of Lemna is an  -Ketol Derivative of Linolenic Acid

Yokoyama, Mineyuki; Yamaguchi, Syuhei; Inomata, Shinji; Komatsu, Kazuhiko; Yoshida, Seiichi; Iida, Toshii; Yokokawa, Yoshihiro; Yamaguchi, Michihiro; Kaihara, Sumiko; Takimoto, Atsushi

doi:10.1093/pcp/41.1.110

Cited by 89 publications

(65 citation statements)

References 9 publications

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“…Support for this hypothesis comes from two recent studies. One study provided evidence that 9-hydroxy-10-oxo-12,15-octadecadienoic acid, the ␣-ketol produced by the action of LeAOS3 on 9-HPOT, functions as a signal for flower development in Lemna paucicostata (48). Another study showed that transgenic potato plants depleted in the expression of a 9-LOX gene exhibited abnormal tuber development (49).…”

Section: Table II Substrate Specificity Of Recombinant Leaos3mentioning

confidence: 99%

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Itoh¹,

Schilmiller

McCaig³

et al. 2002

Journal of Biological Chemistry

105

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Allene oxide synthase (AOS) is a cytochrome P-450 (CYP74A) that catalyzes the first step in the conversion of 13-hydroperoxy linolenic acid to jasmonic acid and related signaling molecules in plants. Here, we report the molecular cloning and characterization of a novel AOS-encoding cDNA (LeAOS3) from Lycopersicon esculentum whose predicted amino acid sequence classifies it as a member of the CYP74C subfamily of enzymes that was hitherto not known to include AOSs. Recombinant LeAOS3 expressed in Escherichia coli showed spectral characteristics of a P-450. The enzyme transformed 9-and 13-hydroperoxides of linoleic and linolenic acid to ␣-ketol, ␥-ketol, and cyclopentenone compounds that arise from spontaneous hydrolysis of unstable allene oxides, indicating that the enzyme is an AOS. Kinetic assays demonstrated that LeAOS3 was Ϸ10-fold more active against 9-hydroperoxides than the corresponding 13-isomers. LeAOS3 transcripts accumulated in roots, but were undetectable in aerial parts of mature plants. In contrast to wild-type plants, LeAOS3 expression was undetectable in roots of a tomato mutant that is defective in jasmonic acid signaling. These findings suggest that LeAOS3 plays a role in the metabolism of 9-lipoxygenase-derived hydroperoxides in roots, and that this branch of oxylipin biosynthesis is regulated by the jasmonate signaling cascade.Oxylipins comprise a group of biologically active compounds that are produced by oxidative metabolism of polyunsaturated fatty acids. Members of the eicosanoid family of lipid mediators have been studied extensively with respect to their biosynthesis from arachidonic acid and their function in diverse physiological processes in animal cells (1). In plants, which lack arachidonic acid, oxygenated derivatives of C 18 fatty acids participate in the regulation of many defense-related and developmental processes. The biosynthesis of most phytooxylipins is initiated by lipoxygenase (LOX), 1 which adds molecular oxygen to either the C-9 or C-13 position of linolenic or linoleic acid (2). The resulting hydroperoxides are further metabolized by several enzymes including three closely related members of the CYP74 family of cytochromes P-450: allene oxide synthase (AOS), hydroperoxide lyase (HPL), and divinyl ether synthase (DES). Indeed, much of the structural and functional diversity in oxylipin metabolism in plants can be accounted for by the activity of CYP74s that metabolize 9-and 13-hydroperoxides to a wide range of products (3). In contrast to typical P-450 monooxygenases, CYP74 P-450s do not require O 2 and a NADPHdependent P-450 reductase for activity. Rather, they use a hydroperoxide group both as the oxygen donor and as a source of reducing equivalents (4, 5). This unique catalytic feature is shared by thromboxane synthase and prostacyclin synthase, two P-450 enzymes involved in the synthesis of eicosanoids (6). A greater understanding of the biochemical and physiological function of this atypical class of P-450 enzymes promises to provide new insight into the evolution ...

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Section: Table II Substrate Specificity Of Recombinant Leaos3mentioning

confidence: 99%

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Itoh¹,

Schilmiller

McCaig³

et al. 2002

Journal of Biological Chemistry

105

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“…2002). The total structure of KODA, including the a-ketol, carboxylic acid and two cis-olefin moieties, is strictly required for flower-inducing activity in Lemna (Yokoyama et al 2000). In this report, we showed that two other reactants of KODA and norepinephrine, which also exhibit flower-inducing activity, retain the essential structure of KODA.…”

Section: Discussionmentioning

confidence: 62%

“…KODA was prepared using lipoxygenase from rice germ and allene oxide synthase from flax seed (Yokoyama et al 2000). In order to obtain the reactants, KODA (6.45 mmol) in distilled water (3.3 L) was added to NE (6.45 mmol in 645 mL of water) in 1 M Tris-HCl buffer (pH 8.0, 320 mL) and the solution was incubated for 160 hr at 25°C.…”

Section: Analyses Of Fn7 and Fn10mentioning

confidence: 99%

Identification of reaction products of 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid (KODA) and norepinephrine that strongly induce flowering in Lemna

Yokoyama

Yamaguchi²,

Suzuki

et al. 2008

Plant Biotechnology

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“…Endogenous levels of KODA are elevated during the latter half of flower-inductive darkness, and floral induction can be canceled by the night-break treatment, that is a light exposure during the 8th hour of inductive darkness (Suzuki et al 2003). KODA was originally isolated from Lemna paucicostata during experiments related to flowering and it showed flower-inducing activity when applied exogenously (Yamaguchi et al 2001;Yokoyama et al 2000). However, exogenous application of KODA to P. nil seedlings under long day non-inductive conditions showed no effects on flowering.…”

mentioning

confidence: 99%

Effects of 9,10-ketol-octadecadienoic acid (KODA) application on single and marginal short-day induction of flowering in Pharbitis nil cv. Violet

Ono

Kataoka

Yokoyama

et al. 2013

Plant Biotechnology

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Seedlings of the Japanese morning glory (Pharbitis nil, formerly Ipomoea nil) cv. Violet are induced to flower by a single short day treatment, and endogenous levels of 9,10-ketol-octadecadienoic acid (KODA) in cotyledons were found to correlate with this mode of short-day induction. When 100 µM KODA solution was sprayed on 7-day-old seedlings before and after a marginal short-day induction, the seedlings bore approximately 4 flower buds, a one-bud increase compared with control seedlings. In treated seedlings, the second node most commonly bore the first flower bud, one node lower than in the control seedlings. We then used RT-PCR to determine expression levels of 10 genes related to photoperiodic induction of flowering. In the cotyledons, no differences were observed in expression of any genes, including P. nil FLOWERING TIME LOCUS T (PnFT1 and PnFT2), between the KODA-treated and the control seedlings. In the apical buds, P. nil APETALA1 (PnAP1) was expressed earlier in the KODA-treated seedlings than in the control seedlings. A decrease in the expression of P. nil TERMINAL FLOWER1b (PnTFL1b) was also observed in the KODA-treated seedlings. These results suggest that KODA acts as a weak enhancer of flower bud formation.

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Stress-Induced Factor Involved in Flower Formation of Lemna is an -Ketol Derivative of Linolenic Acid

Cited by 89 publications

References 9 publications

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Identification of reaction products of 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid (KODA) and norepinephrine that strongly induce flowering in Lemna

Effects of 9,10-ketol-octadecadienoic acid (KODA) application on single and marginal short-day induction of flowering in Pharbitis nil cv. Violet

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