Coordinated activation of metabolic pathways for antioxidants and defence compounds by jasmonates and their roles in stress tolerance in Arabidopsis

Sasaki-Sekimoto, Yuko; Taki, Nozomi; Obayashi, Takeshi; Aono, Mitsuko; Matsumoto, Fuminori; Sakurai, Nozomu; Suzuki, Hideyuki; Hirai, Masami Yokota; Noji, Masaaki; Saito, Kazuki; Masuda, Tatsuru; Takamiya, Ken Ichiro; Shibata, Daisuke; Ohta, Hiroyuki

doi:10.1111/j.1365-313x.2005.02560.x

Cited by 328 publications

(234 citation statements)

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“…Jasmonate treatment also led to ascorbate accumulation in Arabidopsis as well as induction of both the VTC2 and VTC5 genes (26). The expression of the VTC5 gene seemed, however, to be more responsive to jasmonate treatment as well as to induction by ozone exposure (26), which might indicate that VTC5 only contributes significantly to ascorbate synthesis under certain stress conditions. Importantly, with the identification of VTC5, it has now become possible to find out whether pathways other than the Smirnoff-Wheeler pathway significantly contribute to plant vitamin C synthesis.…”

Section: Discussionmentioning

confidence: 83%

“…Exposure of Arabidopsis plants to high light led to increased ascorbate contents as well as increased expression of VTC5 and, more importantly, VTC2 (16). Jasmonate treatment also led to ascorbate accumulation in Arabidopsis as well as induction of both the VTC2 and VTC5 genes (26). The expression of the VTC5 gene seemed, however, to be more responsive to jasmonate treatment as well as to induction by ozone exposure (26), which might indicate that VTC5 only contributes significantly to ascorbate synthesis under certain stress conditions.…”

Section: Discussionmentioning

confidence: 92%

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A Second GDP-l-galactose Phosphorylase in Arabidopsis en Route to Vitamin C

Linster¹,

Adler²,

Webb³

et al. 2008

Journal of Biological Chemistry

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The Arabidopsis thaliana VTC2 gene encodes an enzyme that catalyzes the conversion of GDP-L-galactose to L-galactose 1-phosphate in the first committed step of the SmirnoffWheeler pathway to plant vitamin C synthesis. Mutations in VTC2 had previously been found to lead to only partial vitamin C deficiency. Here we show that the Arabidopsis gene At5g55120 encodes an enzyme with high sequence identity to VTC2. Designated VTC5, this enzyme displays substrate specificity and enzymatic properties that are remarkably similar to those of VTC2, suggesting that it may be responsible for residual vitamin C synthesis in vtc2 mutants. The exact nature of the reaction catalyzed by VTC2/VTC5 is controversial because of reports that kiwifruit and Arabidopsis VTC2 utilize hexose 1-phosphates as phosphorolytic acceptor substrates. Using liquid chromatography-mass spectroscopy and a VTC2-H238N mutant, we provide evidence that the reaction proceeds through a covalent guanylylated histidine residue within the histidine triad motif. Moreover, we show that both the Arabidopsis VTC2 and VTC5 enzymes catalyze simple phosphorolysis of the guanylylated enzyme, forming GDP and L-galactose 1-phosphate from GDP-L-galactose and phosphate, with poor reactivity of hexose 1-phosphates as phosphorolytic acceptors. Indeed, the endogenous activities from Japanese mustard spinach, lemon, and spinach have the same substrate requirements. These results show that Arabidopsis VTC2 and VTC5 proteins and their homologs in other plants are enzymes that guanylylate a conserved active site His residue with GDP-L-galactose, forming L-galactose 1-phosphate for vitamin C synthesis, and regenerate the enzyme with phosphate to form GDP.Vitamin C (L-ascorbic acid) is the most abundant soluble antioxidant in plants, in which it plays crucial roles in protection against oxidative damage and is used as a cofactor for several enzymes. It is synthesized via reactions initially proposed by Wheeler et al. (1) that are distinct from those used in vitamin C biosynthesis in animals. Although the Smirnoff-Wheeler pathway, arising from GDP-D-mannose and involving L-galactose formation, might not be the only route to vitamin C biosynthesis in plants (alternative pathways arising from myo-inositol and methylgalacturonate or involving L-gulose formation have been proposed; for reviews, see Refs. 2 and 3), it is undoubtedly the pathway that has received the strongest biochemical and genetic support in recent years (4 -9).Of the four loci (VTC1-4) that have been found to be mutated in vitamin C-deficient Arabidopsis thaliana plants (10, 11), three are now known to encode enzymes involved in the Smirnoff-Wheeler pathway. VTC1 encodes GDP-mannose pyrophosphorylase (12), whereasVTC4 encodes L-Gal-1-P 3 phosphatase (8). In 2007 the VTC2 gene product was identified as the enzyme that produces L-Gal-1-P from GDP-L-galactose, which completed the characterization of the 10 enzymatic steps leading from D-glucose to L-ascorbic acid (13,14). VTC2 is a member of the D-galactose-1-phosphate ...

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 92%

A Second GDP-l-galactose Phosphorylase in Arabidopsis en Route to Vitamin C

Linster¹,

Adler²,

Webb³

et al. 2008

Journal of Biological Chemistry

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“…Intracellular GSH regulates stomatal movement by acting together with signal molecules. Jasmonic acid regulates Arabidopsis GSH concentration and genes for GSH metabolism (Sasaki-Sekimoto et al 2005). Glutathione functions as a signal molecule during MeJA signaling in guard cells.…”

Section: Signaling Cross Talk Of Glutathionementioning

confidence: 99%

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

Hasanuzzaman

Nahar

Anee

et al. 2017

Physiol Mol Biol Plants

596

284

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Glutathione (GSH; c-glutamyl-cysteinyl-glycine) is a small intracellular thiol molecule which is considered as a strong non-enzymatic antioxidant. Glutathione regulates multiple metabolic functions; for example, it protects membranes by maintaining the reduced state of both a-tocopherol and zeaxanthin, it prevents the oxidative denaturation of proteins under stress conditions by protecting their thiol groups, and it serves as a substrate for both glutathione peroxidase and glutathione S-transferase. By acting as a precursor of phytochelatins, GSH helps in the chelating of toxic metals/metalloids which are then transported and sequestered in the vacuole. The glyoxalase pathway (consisting of glyoxalase I and glyoxalase II enzymes) for detoxification of methylglyoxal, a cytotoxic molecule, also requires GSH in the first reaction step. For these reasons, much attention has recently been directed to elucidation of the role of this molecule in conferring tolerance to abiotic stress. Recently, this molecule has drawn much attention because of its interaction with other signaling molecules and phytohormones. In this review, we have discussed the recent progress in GSH biosynthesis, metabolism and its role in abiotic stress tolerance.

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“…JA signaling upregulates both stress responsive 13 and S uptake/metabolism genes. 9 Ethylene signaling also upregulates stress responsive genes, but the contribution of these genes to acquisition of Se resistance in plants is unclear. In this context, it is noteworthy that transgenic Arabidopsis thaliana that overproduce Arabidopsis halleri plant defensin (AhPDF1.1) 20 showed a slight but significant increase in tolerance to selenite compared to wild-type plants (Fig.…”

mentioning

confidence: 99%

“…1 These include the gene encoding allene oxide synthase (AOS), a key enzyme in JA biosynthesis, 8 and known to be induced by MeJA. 9 Another selenite-induced gene was PDF1.2 which encodes a plant defensin that requires concomitant triggering of the ethylene and JA pathway for its induction. 10 Transgenic AOS promoter::GUS and PDF1.2 promoter::GUS plants exhibited GUS activity in leaves of selenite-treated plants ( Fig.…”

mentioning

confidence: 99%