Engineering ascorbic acid biosynthetic pathway in Arabidopsis leaves by single and double gene transformation

Zhou, Yin; Tao, Qin; Wang, Z. N.; Fan, Ruixin; Li, Y.; Sun, Xiaofen; Tang, Kexuan

doi:10.1007/s10535-012-0119-x

Cited by 37 publications

(34 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Missense mutations in the Arabidopsis GMP gene reduced ascorbate to 25% of wild-type levels, supporting its important role in L-galactose ascorbate biosynthesis [21][22][23]. Increased expression of the GMP gene has increased ascorbate concentrations in a range of species, including 1.3-fold in Arabidopsis [24], 2.5-fold in tobacco [25], 1.4-to 1.7-fold in tomato (Solanum lycopersicum L.) [26,27], and 1.5-fold in rice [28] (Table 1). Increased co-expression of the GMP + GME genes in tomato increased ascorbate concentrations 2.0-fold, a greater increase than the individual genes alone, suggesting that GMP may act synergistically with GME to increase ascorbate concentrations in tomato [26].…”

Section: Gdp-d-mannose Pyrophosphorylase (Gmp)mentioning

confidence: 94%

Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

Broad

Bonneau

Hellens

et al. 2020

IJMS

View full text Add to dashboard Cite

Abiotic stresses, such as drought, salinity, and extreme temperatures, are major limiting factors in global crop productivity and are predicted to be exacerbated by climate change. The overproduction of reactive oxygen species (ROS) is a common consequence of many abiotic stresses. Ascorbate, also known as vitamin C, is the most abundant water-soluble antioxidant in plant cells and can combat oxidative stress directly as a ROS scavenger, or through the ascorbate–glutathione cycle—a major antioxidant system in plant cells. Engineering crops with enhanced ascorbate concentrations therefore has the potential to promote broad abiotic stress tolerance. Three distinct strategies have been utilized to increase ascorbate concentrations in plants: (i) increased biosynthesis, (ii) enhanced recycling, or (iii) modulating regulatory factors. Here, we review the genetic pathways underlying ascorbate biosynthesis, recycling, and regulation in plants, including a summary of all metabolic engineering strategies utilized to date to increase ascorbate concentrations in model and crop species. We then highlight transgene-free strategies utilizing genome editing tools to increase ascorbate concentrations in crops, such as editing the highly conserved upstream open reading frame that controls translation of the GDP-L-galactose phosphorylase gene.

show abstract

Section: Gdp-d-mannose Pyrophosphorylase (Gmp)mentioning

confidence: 94%

Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

Broad

Bonneau

Hellens

et al. 2020

IJMS

View full text Add to dashboard Cite

show abstract

“…We have previously shown that the enzyme GDP-L-galactose phosphorylase (GGP) (encoded by the gene GGP, also known as VTC2) is at a central control point of vitamin C biosynthesis as the first committed step; overexpression of this gene in plants results in a significant increase in tissue ascorbate concentrations (Laing et al, 2007;Bulley et al, 2009Bulley et al, , 2012, suggesting it may serve a regulatory role, possibly balancing fluxes between ascorbate and GDP-L-fucose (Bonin et al, 1997). No other single genes in the L-galactose pathway have a significant effect on ascorbate (Bulley et al, 2012;Zhou et al, 2012), although GDP mannose epimerase (GME) acts synergistically with GGP to increase leaf ascorbate still further (Bulley et al, 2009). In addition, during fruit development, transcript levels of GGP and GME parallel the increase in ascorbate (Bulley et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

An Upstream Open Reading Frame Is Essential for Feedback Regulation of Ascorbate Biosynthesis in Arabidopsis

et al. 2015

View full text Add to dashboard Cite

Ascorbate (vitamin C) is an essential antioxidant and enzyme cofactor in both plants and animals. Ascorbate concentration is tightly regulated in plants, partly to respond to stress. Here, we demonstrate that ascorbate concentrations are determined via the posttranscriptional repression of GDP-L-galactose phosphorylase (GGP), a major control enzyme in the ascorbate biosynthesis pathway. This regulation requires a cis-acting upstream open reading frame (uORF) that represses the translation of the downstream GGP open reading frame under high ascorbate concentration. Disruption of this uORF stops the ascorbate feedback regulation of translation and results in increased ascorbate concentrations in leaves. The uORF is predicted to initiate at a noncanonical codon (ACG rather than AUG) and encode a 60-to 65-residue peptide. Analysis of ribosome protection data from Arabidopsis thaliana showed colocation of high levels of ribosomes with both the uORF and the main coding sequence of GGP. Together, our data indicate that the noncanonical uORF is translated and encodes a peptide that functions in the ascorbate inhibition of translation. This posttranslational regulation of ascorbate is likely an ancient mechanism of control as the uORF is conserved in GGP genes from mosses to angiosperms.

show abstract

“…The separate overexpression of six genes in the vitC de novo biosynthetic pathway (Zhou et al ., ) led to the modest increases in vitamin, despite some genes being highly overexpressed (up to 42‐fold). When transgenes were combined in couples, increases were greater even with a substantial reduction in the overexpression factor.…”

Section: Flux Control and Concentration Control Are Different Conceptsmentioning

confidence: 99%

Control limits for accumulation of plant metabolites: brute force is no substitute for understanding

Morandini

2013

Plant Biotechnology Journal

View full text Add to dashboard Cite

SummaryWhich factors limit metabolite accumulation in plant cells? Are theories on flux control effective at explaining the results? Many biotechnologists cling to the idea that every pathway has a rate limiting enzyme and target such enzymes first in order to modulate fluxes. This often translates into large effects on metabolite concentration, but disappointing small increases in flux. Rate limiting enzymes do exist, but are rare and quite opposite to what predicted by biochemistry. In many cases however, flux control is shared among many enzymes. Flux control and concentration control can (and must) be distinguished and quantified for effective manipulation. Flux control for several 'building blocks' of metabolism is placed on the demand side, and therefore increasing demand can be very successful. Tampering with supply, particularly desensitizing supply enzymes, is usually not very effective, if not dangerous, because supply regulatory mechanisms function to control metabolite homeostasis. Some important, but usually unnoticed, metabolic constraints shape the responses of metabolic systems to manipulation: mass conservation, cellular resource allocation and, most prominently, energy supply, particularly in heterotrophic tissues. The theoretical basis for this view shall be explored with recent examples gathered from the manipulation of several metabolites (vitamins, carotenoids, amino acids, sugars, fatty acids, polyhydroxyalkanoates, fructans and sugar alcohols). Some guiding principles are suggested for an even more successful engineering of plant metabolism.Rate limiting steps: do they exist? Yes, but they are not quite as expectedAs most research in plant biotechnology aims at manipulating the amount of selected metabolic products, the question arises: what limits their accumulation? The dominant textbook wisdom wasand partially still is -that in every metabolic pathway there is a reaction limiting the flux (defined as the 'rate limiting step' (RLS) of the pathway), and therefore ultimately the accumulation of downstream metabolites. As a sample quote of this belief, take the following from Ishihara et al. Let us first clarify the relationship between flux and metabolite accumulation. If flux remains unchanged, a metabolite concentration can increase only if other metabolite(s) in the pathway decrease; a constant flux imposes a constraint on the achievable fold accumulation of any metabolite. On the contrary, when flux increases, the end product (as well as other intermediates) can accumulate several folds. It must be noted that even small changes in flux (say a few percent of usual flux) may lead to a mM increase of a metabolite if the accumulation is protracted for many days.The idea of the RLS can be likened, in its simplest and extreme form, to a tollgate on a highway (Figure 1): the number of cars processed in unit time is independent from the number of cars waiting in the queue or of those beyond the gate. In metabolic terms, this comparison is untenable, not only because the rate of an enzymatic r...

show abstract

Engineering ascorbic acid biosynthetic pathway in Arabidopsis leaves by single and double gene transformation

Cited by 37 publications

References 40 publications

Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

An Upstream Open Reading Frame Is Essential for Feedback Regulation of Ascorbate Biosynthesis in Arabidopsis

Control limits for accumulation of plant metabolites: brute force is no substitute for understanding

Contact Info

Product

Resources

About