Conversion of<scp>L</scp>-Galactono-1,4-lactone to<scp>L</scp>-Ascorbate Is Regulated by the Photosynthetic Electron Transport Chain in<i>Arabidopsis</i>

Yabuta, Yukinori; Maruta, Takanori; Nakamura, Ayana; Mieda, Takahiro; Yoshimura, Kazuya; Ishikawa, Takahiro; Shigeoka, Shigeru

doi:10.1271/bbb.80284

Cited by 26 publications

(16 citation statements)

References 49 publications

(87 reference statements)

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“…Transcript levels of GLDH in young rosette leaves of Arabidopsis increase about 2-fold during the day (Tamaoki et al, 2003). The conversion to ascorbate by L-galactono-1,4-lactone is also controlled by photosynthetic electron transport, although not at the transcriptional level (Yabuta et al, 2008). Transcriptional regulation appears to be specific to one portion of the AsA biosynthetic network, since myoinositol oxygenase expression was unaffected by AMR1 transcript levels.…”

Section: Discussionmentioning

confidence: 98%

AMR1, an Arabidopsis Gene That Coordinately and Negatively Regulates the Mannose/l-Galactose Ascorbic Acid Biosynthetic Pathway

et al. 2009

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Ascorbic acid (AsA) biosynthesis in plants occurs through a complex, interconnected network with mannose (Man), myoinositol, and galacturonic acid as principal entry points. Regulation within and between pathways in the network is largely uncharacterized. A gene that regulates the Man/L-galactose (L-Gal) AsA pathway, AMR1 (for ascorbic acid mannose pathway regulator 1), was identified in an activation-tagged Arabidopsis (Arabidopsis thaliana) ozone-sensitive mutant that had 60% less leaf AsA than wild-type plants. In contrast, two independent T-DNA knockout lines disrupting AMR1 accumulated 2-to 3-fold greater foliar AsA and were more ozone tolerant than wild-type controls. Real-time reverse transcription-polymerase chain reaction analysis of steady-state transcripts of genes involved in AsA biosynthesis showed that AMR1 negatively affected the expression of GDP-Man pyrophosphorylase, GDP-L-Gal phosphorylase, L-Gal-1-phosphate phosphatase, GDP-Man-3#,5#-epimerase, L-Gal dehydrogenase, and L-galactono-1,4-lactone dehydrogenase, early and late enzymes of the Man/L-Gal pathway to AsA. AMR1 expression appears to be developmentally and environmentally controlled. As leaves aged, AMR1 transcripts accumulated with a concomitant decrease in AsA. AMR1 transcripts also decreased with increased light intensity. Thus, AMR1 appears to play an important role in modulating AsA levels in Arabidopsis by regulating the expression of major pathway genes in response to developmental and environmental cues.

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Section: Discussionmentioning

confidence: 98%

AMR1, an Arabidopsis Gene That Coordinately and Negatively Regulates the Mannose/l-Galactose Ascorbic Acid Biosynthetic Pathway

et al. 2009

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“…An A. thaliana line (ppr40-1) that has impaired electron flow at complex III showed decreased levels of total ascorbate and enhanced activity of GLDH and ascorbateglutathione cycle enzymes (58). Similarly, inhibition of mitochondrial respiratory electron transport at the levels of complex I, complex II, or complex IV resulted in a 50% decrease in total ascorbate levels in A. thaliana (59). It is well known that plant mitochondria are the place where the last step of vitamin C biosynthesis occurs in plants.…”

Section: Discussionmentioning

confidence: 99%

Impact of Oxidative Stress on Ascorbate Biosynthesis in Chlamydomonas via Regulation of the VTC2 Gene Encoding a GDP-l-galactose Phosphorylase

Urzica

Adler

Page

et al. 2012

Journal of Biological Chemistry

107

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Background: Ascorbate biosynthesis in plants occurs mainly via the L-galactose pathway. Results: Chlamydomonas reinhardtii VTC2 encodes a GDP-L-galactose phosphorylase whose transcript levels are induced in response to oxidative stress concurrent with increased ascorbate accumulation. Conclusion: Increased oxidative stress in C. reinhardtii results in an enzymatic and non-enzymatic antioxidant response. Significance: First characterization of C. reinhardtii ascorbate biosynthesis and recycling pathways.

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“…Plant vitamin C content is regulated by environmental factors and especially the light environment (Gatzek et al 2002;Tabata et al 2002;Tamaoki et al 2003;Chen and Gallie 2004;Yabuta et al 2008; Bartoli et al 2009). The major biosynthetic pathway of AsA in plants (L-galactose pathway, Wheeler et al 1998) involves ten enzymatic steps ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Light affects ascorbate content and ascorbate-related gene expression in tomato leaves more than in fruits

Massot

Stevens

Génard

et al. 2011

Planta

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Little is known about the light regulation of vitamin C synthesis in fruits. In contrast, previous studies in leaves revealed that VTC2 (coding for GDP-L: -galactose phosphorylase) was one of the key genes up-regulated by light in leaves. Our objective was to determine how the expression of ascorbate (AsA) synthesis genes in tomato (Solanum lycopersicum) was modified according to light irradiance in both leaves and fruits. Seven days of shading strongly decreased total ascorbate (reduced and oxidized form) content in leaves (50%) and to a lesser extent in fruits (10%). Among the last six steps of AsA biosynthesis, only two genes, VTC2 and GPP1 (one of the two unigenes coding for L: -galactose-1-P phosphatase in tomato), were down-regulated by long-term shading in red ripe fruits, compared to seven genes regulated in leaves. This underlines that light affects AsA-related gene expression more in leaves than in ripening fruits. Moreover, this study reveals strong daily changes in transcript levels of enzymes of the AsA biosynthetic pathway in leaves (11 of the 12 studied genes showed significant changes in their expression pattern). Among those genes, we found that diurnal variation in transcript levels of VTC2 and GME1 correlated to leaf AsA content measured 8 h later. This study provides a new hypothesis on the role of GME1 in addition to VTC2 in light-regulated AsA biosynthesis.

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Conversion ofL-Galactono-1,4-lactone toL-Ascorbate Is Regulated by the Photosynthetic Electron Transport Chain inArabidopsis

Cited by 26 publications

References 49 publications

AMR1, an Arabidopsis Gene That Coordinately and Negatively Regulates the Mannose/l-Galactose Ascorbic Acid Biosynthetic Pathway

AMR1, an Arabidopsis Gene That Coordinately and Negatively Regulates the Mannose/l-Galactose Ascorbic Acid Biosynthetic Pathway

Impact of Oxidative Stress on Ascorbate Biosynthesis in Chlamydomonas via Regulation of the VTC2 Gene Encoding a GDP-l-galactose Phosphorylase

Light affects ascorbate content and ascorbate-related gene expression in tomato leaves more than in fruits

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