Engineering increased vitamin C levels in plants by overexpression of a D-galacturonic acid reductase

Agius, Fernanda; González-Lamothe, Rocío; Caballero, José L.; Muñoz‐Blanco, Juan; Botella, Miguel A.; Valpuesta, Victoriano

doi:10.1038/nbt777

Cited by 510 publications

(428 citation statements)

References 27 publications

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“…1), the reaction catalyzed by GalUR (Enzyme Commission [EC] 1.1.1.203) in strawberry has been the most extensively studied (Agius et al, 2003). D-Galacturonate has been suggested to be an alternative substrate for the synthesis of AsA in fruit skin by precursor feeding experiments in apple fruit tissues (Li et al, 2008), and biosynthesis proceeding via GalUR has been suggested to play a more significant role in the later stages of fruit ripening when breakdown of cell wall pectin takes place (Melino et al, 2009;Cruz-Rus et al, 2011;Badejo et al, 2012).…”

Section: Candidate Genes Regulating Asa Concentrationsmentioning

confidence: 99%

“…However, apart from GGP (Bulley et al, 2012), overexpression of these structural genes has to date had limited success in altering the fruit AsA pool (Agius et al, 2003;Bulley et al, 2009;Haroldsen et al, 2011).…”

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confidence: 99%

“…The biosynthesis of AsA proceeds via L-Gal (Wheeler et al, 1998), although conclusive evidence for all steps has only relatively recently become available (Conklin et al, 2006;Laing et al, 2007). Alternative biosynthetic routes involving uronic acids (Davey et al, 1999;Agius et al, 2003), L-gulose (Wolucka and Van Montagu, 2003), or myoinositol (Lorence et al, 2004) have been proposed in several plant species, including apple Razavi et al, 2005; Fig. 1), but their physiological relevance and contribution to the AsA pool is still far from clear in most plant species, with the possible exception of strawberry (Fragaria 3 ananassa; Agius et al, 2003;Cruz-Rus et al, 2011;Zorrilla-Fontanesi et al, 2011).…”

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Allelic Variation in Paralogs of GDP-l-Galactose Phosphorylase Is a Major Determinant of Vitamin C Concentrations in Apple Fruit

et al. 2012

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To identify the genetic factors underlying the regulation of fruit vitamin C (L-ascorbic acid [AsA]) concentrations, quantitative trait loci (QTL) studies were carried out in an F1 progeny derived from a cross between the apple (Malus 3 domestica) cultivars Telamon and Braeburn over three years. QTL were identified for AsA, glutathione, total antioxidant activity in both flesh and skin tissues, and various quality traits, including flesh browning. Four regions on chromosomes 10, 11, 16, and 17 contained stable fruit AsA-QTL clusters. Mapping of AsA metabolic genes identified colocations between orthologs of GDP-L-galactose phosphorylase (GGP), dehydroascorbate reductase (DHAR), and nucleobase-ascorbate transporter within these QTL clusters. Of particular interest are the three paralogs of MdGGP, which all colocated within AsA-QTL clusters. Allelic variants of MdGGP1 and MdGGP3 derived from the cultivar Braeburn parent were also consistently associated with higher fruit total AsA concentrations both within the mapping population (up to 10-fold) and across a range of commercial apple germplasm (up to 6-fold). Striking differences in the expression of the cv Braeburn MdGGP1 allele between fruit from high-and low-AsA genotypes clearly indicate a key role for MdGGP1 in the regulation of fruit AsA concentrations, and this MdGGP allele-specific single-nucleotide polymorphism marker represents an excellent candidate for directed breeding for enhanced fruit AsA concentrations. Interestingly, colocations were also found between MdDHAR3-3 and a stable QTL for browning in the cv Telamon parent, highlighting links between the redox status of the AsA pool and susceptibility to flesh browning.

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Section: Candidate Genes Regulating Asa Concentrationsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Allelic Variation in Paralogs of GDP-l-Galactose Phosphorylase Is a Major Determinant of Vitamin C Concentrations in Apple Fruit

et al. 2012

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“…Generally, animals use the uronic acid pathway (10), whereas several different mechanisms have been reported in plants (11)(12)(13). Yeasts are unusual in that they predominantly synthesize erythroascorbate, a five-carbon analogue of ascorbate that possesses all of its biochemical properties (14).…”

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confidence: 99%

Vitamin C biosynthesis in trypanosomes: A role for the glycosome

Wilkinson

Prathalingam

Taylor

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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The capacity to synthesize vitamin C (ascorbate) is widespread in eukaryotes but is absent from humans. The last step in the biosynthetic pathway involves the conversion of an aldonolactone substrate to ascorbate, a reaction catalyzed by members of an FAD-dependent family of oxidoreductases. Here we demonstrate that both the African trypanosome, Trypanosoma brucei, and the American trypanosome, Trypanosoma cruzi, have the capacity to synthesize vitamin C and show that this reaction occurs in a unique single-membrane organelle, the glycosome. The corresponding T. brucei flavoprotein (TbALO) obeys Michaelis-Menten kinetics and can utilize both L-galactono-␥-lactone and D-arabinono-␥-lactone as substrate, properties characteristic of plant and fungal enzymes. We could detect no activity toward the mammalian enzyme substrate L-gulono-␥-lactone. TbALO null mutants (bloodstream form) were found to display a transient growth defect, a trait that was enhanced when they were cultured in medium in which the essential serum component had been pretreated with ascorbate oxidase to deplete vitamin C. It is implicit, therefore, that bloodstream-form trypanosomes also possess a capacity for ascorbate transport.ascorbic acid ͉ FAD ͉ oxidase ͉ Trypanosoma brucei

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“…Although additional pathways for ascorbate synthesis may contribute to the accumulation of this metabolite in plants (10,11), the L-galactose pathway is clearly a major contributor. The availability of VTC2 and those encoding other members of the L-galactose pathway for ascorbate synthesis will facilitate identification of optimal gene targets for genetic engineering through either biotechnology or targeted breeding approaches.…”

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Completing a pathway to plant vitamin C synthesis

Giovannoni

2007

Proc. Natl. Acad. Sci. U.S.A.

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Engineering increased vitamin C levels in plants by overexpression of a D-galacturonic acid reductase

Cited by 510 publications

References 27 publications

Allelic Variation in Paralogs of GDP-l-Galactose Phosphorylase Is a Major Determinant of Vitamin C Concentrations in Apple Fruit

Allelic Variation in Paralogs of GDP-l-Galactose Phosphorylase Is a Major Determinant of Vitamin C Concentrations in Apple Fruit

Vitamin C biosynthesis in trypanosomes: A role for the glycosome

Completing a pathway to plant vitamin C synthesis

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