The contribution of adenosine 5′-diphosphoglucose pyrophosphorylase to the control of starch synthesis in potato tubers

Sweetlove, Lee J.; Müller‐Röber, Bernd; Willmitzer, Lothar; Hill, Steven A.

doi:10.1007/s004250050640

Cited by 68 publications

(89 citation statements)

References 23 publications

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“…It is known for sure [10] that biosynthesis and deposition of storage starch in potato tubers involve at least four main groups of enzymes: ADP glucose pyrophosphorylases (AGP), starch synthases (SS), enzymes catalyzing the branching of glucan chains (BE), and debranching enzymes (DBE). AGP cata lyze production of ADP glucose (this reaction restricts the total rate of starch biosynthesis in tubers) [24]. Because expression of rolB and rolC genes did not induce considerable changes in the total content of starch in tubers of transformed plants (Table 1), one can assume that these transgenes do not affect the ini tial stage of starch biosynthesis associated with AGP activity.…”

Section: Discussionmentioning

confidence: 99%

Agrobacterial rol genes modify thermodynamic and structural properties of starch in microtubers of transgenic potato

Aksenova

Wasserman

Сергеева

et al. 2010

Russ J Plant Physiol

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INTRODUCTIONTuber formation in potato is regulated by numerous external and internal factors with phytohormones being of special importance [1]. In order to investigate the hormonal control over tuber formation, some researchers used transformed potato plants expressing rolB and rolC genes of Agrobacterium rhizogenes [2]. Biochemical mechanism of the operation of rol trans genes remains debatable; however, it was shown that their role in higher plants resembles to the effect of phytohormones: auxins in case rolB and cytokinins in case rolC [3]. It is assumed that hormone like effect of rol genes may be related to their influence on the metabolism of auxins and cytokinins or to the changes in plant cell sensitivity to these phytohormones [3]. It was also shown that the intensity of the effect of rol genes on morphogenesis of potato plants greatly depends on the used promoter governing organospec ificity of gene expression [4].It order to investigate the effect of genes rolB and rolC on tuber formation, we used B33 class I patatin promoter, which ensured preferred expression of B33::rolC and B33::rolB in growing potato tubers [5]. These experiments showed that transgenes induced numerous morphological changes accompanied by changes in the activity of some enzymes of carbohy drate metabolism, the content of soluble sugars [6], and the number and size of starch granules [7]. The obtained data suggested that transgenes rolB and rolC might also modify qualitative characteristics of storage starch, which by volume and biological role is the Abstract-Wild type (WT) plants of potato (Solanum tuberosum L.) and their transgenic forms carrying agro bacterial genes rolB or rolC under the control of B33 class I patatin promoter were cultured in vitro on MS medium with 2% sucrose in a controlled climate chamber at 16 h illumination and 22°C. These plants were used as a source of single node stem cuttings, which were cultured in darkness on the same medium supple mented with 8% sucrose. The tubers formed on them were used for determination of the structure of native starch using the methods of differential scanning microcalorimetry (DSC), X ray scattering, and scanning electron microscopy. It was found that, in starch from the tubers of rolB plants, the temperature of crystalline lamella melting was lower and their thickness was less than in WT potato. In tubers of rolC plants, starch dif fered from starch in WT plants by a higher melting temperature, considerably reduced melting enthalpy, and a greater thickness of crystalline lamellae. Deconvolution of DSC thermogram makes it possible to interpret the melting of starch from the tubers of rolC plants as the melting of two independent crystalline structures with melting temperatures of 65.0 and 69.8°C. Electron microscopic examination confirmed the earlier obtained data indicating that, in the tubers of rolC plants, starch granules are smaller and in the tubers of rolB plants larger than in WT plants. Possible ways of influence of rol transgenes on structural properties of star...

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Section: Discussionmentioning

confidence: 99%

Agrobacterial rol genes modify thermodynamic and structural properties of starch in microtubers of transgenic potato

Aksenova

Wasserman

Сергеева

et al. 2010

Russ J Plant Physiol

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“…5B). ADP-Glc is formed by AGPase, an enzyme representing an important control step in starch synthesis (Sweetlove et al, 1999) and allosterically affected by the 3-PGA-inorganic phosphate ratio (Preiss 1988;Crevillén et al, 2003). The allosteric stimulation by high phosphoglyceric acid/ inorganic phosphate was also evident in the oilseed rape embryo (Supplemental Fig.…”

Section: Control Of Carbon Partitioning Between Lipid and Starchmentioning

confidence: 94%

Quantitative Multilevel Analysis of Central Metabolism in Developing Oilseeds of Oilseed Rape during in Vitro Culture

et al. 2015

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Seeds provide the basis for many food, feed, and fuel products. Continued increases in seed yield, composition, and quality require an improved understanding of how the developing seed converts carbon and nitrogen supplies into storage. Current knowledge of this process is often based on the premise that transcriptional regulation directly translates via enzyme concentration into flux. In an attempt to highlight metabolic control, we explore genotypic differences in carbon partitioning for in vitro cultured developing embryos of oilseed rape (Brassica napus). We determined biomass composition as well as 79 net fluxes, the levels of 77 metabolites, and 26 enzyme activities with specific focus on central metabolism in nine selected germplasm accessions. Overall, we observed a tradeoff between the biomass component fractions of lipid and starch. With increasing lipid content over the spectrum of genotypes, plastidic fatty acid synthesis and glycolytic flux increased concomitantly, while glycolytic intermediates decreased. The lipid/starch tradeoff was not reflected at the proteome level, pointing to the significance of (posttranslational) metabolic control. Enzyme activity/flux and metabolite/flux correlations suggest that plastidic pyruvate kinase exerts flux control and that the lipid/starch tradeoff is most likely mediated by allosteric feedback regulation of phosphofructokinase and ADP-glucose pyrophosphorylase. Quantitative data were also used to calculate in vivo mass action ratios, reaction equilibria, and metabolite turnover times. Compounds like cyclic 39,59-AMP and sucrose-6-phosphate were identified to potentially be involved in so far unknown mechanisms of metabolic control. This study provides a rich source of quantitative data for those studying central metabolism.Seeds develop by absorbing nutrients from their mother plant and using these to synthesize a combination of starch, protein, and lipid. The size and number of seeds that finally develop determine the crop's yield, while their composition determines the end-use quality of the crop. The conversion of nutrients into storage products involves a complex network of metabolic reactions, many of which are subject to transcriptional, translational, and posttranslational regulation. Attempting to engineer seed composition clearly requires a firm understanding of these regulatory networks.The seed's central metabolism differs markedly from those of both a photosynthesizing leaf and a root. In most species, the immature seed is green for a period during its development, so during this phase it is regarded as being photoheterotrophic. A further level of complexity arises as a result of spatial heterogeneity within the seed (Rolletschek et al., 2011; Borisjuk et al.,

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“…Different studies concerning starch metabolism in potato and tomato have suggested that AGPase activity plays an important role in regulation (Geigenberger et al, 1999;Sweetlove et al, 1999;Geigenberger, 2011). AGPase activity is known to be modulated via several different mechanisms.…”

Section: Effects Of Cytosolic Pepck and Plastidic Nadp-me On Starch Bmentioning

confidence: 99%

Alteration of the Interconversion of Pyruvate and Malate in the Plastid or Cytosol of Ripening Tomato Fruit Invokes Diverse Consequences on Sugar But Similar Effects on Cellular Organic Acid, Metabolism, and Transitory Starch Accumulation

et al. 2012

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The aim of this work was to investigate the effect of decreased cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and plastidic NADP-dependent malic enzyme (ME) on tomato (Solanum lycopersicum) ripening. Transgenic tomato plants with strongly reduced levels of PEPCK and plastidic NADP-ME were generated by RNA interference gene silencing under the control of a ripening-specific E8 promoter. While these genetic modifications had relatively little effect on the total fruit yield and size, they had strong effects on fruit metabolism. Both transformants were characterized by lower levels of starch at breaker stage. Analysis of the activation state of ADP-glucose pyrophosphorylase correlated with the decrease of starch in both transformants, which suggests that it is due to an altered cellular redox status. Moreover, metabolic profiling and feeding experiments involving positionally labeled glucoses of fruits lacking in plastidic NADP-ME and cytosolic PEPCK activities revealed differential changes in overall respiration rates and tricarboxylic acid (TCA) cycle flux. Inactivation of cytosolic PEPCK affected the respiration rate, which suggests that an excess of oxaloacetate is converted to aspartate and reintroduced in the TCA cycle via 2-oxoglutarate/glutamate. On the other hand, the plastidic NADP-ME antisense lines were characterized by no changes in respiration rates and TCA cycle flux, which together with increases of pyruvate kinase and phosphoenolpyruvate carboxylase activities indicate that pyruvate is supplied through these enzymes to the TCA cycle. These results are discussed in the context of current models of the importance of malate during tomato fruit ripening.

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The contribution of adenosine 5′-diphosphoglucose pyrophosphorylase to the control of starch synthesis in potato tubers

Cited by 68 publications

References 23 publications

Agrobacterial rol genes modify thermodynamic and structural properties of starch in microtubers of transgenic potato

Agrobacterial rol genes modify thermodynamic and structural properties of starch in microtubers of transgenic potato

Quantitative Multilevel Analysis of Central Metabolism in Developing Oilseeds of Oilseed Rape during in Vitro Culture

Alteration of the Interconversion of Pyruvate and Malate in the Plastid or Cytosol of Ripening Tomato Fruit Invokes Diverse Consequences on Sugar But Similar Effects on Cellular Organic Acid, Metabolism, and Transitory Starch Accumulation

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