The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Uwe Sonnewald - One of the best experts on this subject based on the ideXlab platform.
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Silencing of α-amylase StAmy23 in potato Tuber leads to delayed Sprouting.
Plant physiology and biochemistry : PPB, 2019Co-Authors: Juan Hou, Uwe Sonnewald, Tengfei Liu, Stephen Reid, Huiling Zhang, Xiaojun Peng, Kaile Sun, Botao SongAbstract:Potato Tuber dormancy is critical for the postharvest quality. The supply of carbohydrates is considered as one of the important factors controlling the rate of potato Tuber Sprouting. Starch is the major carbohydrate reserve in potato Tuber, but very little is known about the specific starch degrading enzymes responsible for controlling Tuber dormancy and Sprouting. In this study, we demonstrate that an α-amylase gene StAmy23 is involved in starch breakdown and regulation of Tuber dormancy. Silencing of StAmy23 delayed Tuber Sprouting by one to two weeks compared with the control. This phenotype is accompanied by reduced levels of reducing sugars and elevated levels of malto-oligosaccharides in Tuber cortex and pith tissue below the bud eye of StAmy23-deficient potato Tubers. Changes in soluble sugars is accompanied by a slight variation of phytoglycogen structure and starch granule size. Our results suggest that StAmy23 may stimulate Sprouting by hydrolyzing soluble phytoglycogen to ensure supply of sugars during Tuber dormancy.
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Impact of ISA silencing on Tuber Sprouting.
2017Co-Authors: Stephanus J. Ferreira, Sophia Sonnewald, Melanie Senning, Michaela Fischer-stettler, Sebastian Streb, Michelle Ast, Ekkehard H. Neuhaus, Samuel C. Zeeman, Uwe SonnewaldAbstract:Tubers of 5 plants each from wild type (WT) and transgenic lines 7, 16 and 39 were stored after harvest at room temperature in darkness. A) Sprouting kinetics. To monitor the impact on dormancy length, 2–5 similar sized Tubers from each plant were picked (n = 13–20) and their Sprouting behaviour was regularly scored over a 15-week period until 100% Sprouting had been reached in wild-type Tubers. A Tuber was considered to sprout when sprouts of 2 mm length became visible. B) Photographs of transgenic (lines 7, 16, 39) and control Tubers taken after 13 weeks of storage showing that the transgenic lines sprout earlier than the wild-type controls (WT). C) Number of sprouts per Tuber. Number of sprouts formed per Tuber were counted from 13–20 individual Tubers. Values represent the mean +/- SE. Significant differences to wild type were calculated using two-tailed t-test assuming equal variances and are indicated by asterisks (**p
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Regulation of potato Tuber Sprouting
Planta, 2014Co-Authors: Sophia Sonnewald, Uwe SonnewaldAbstract:Following Tuber induction, potato Tubers undergo a period of dormancy during which visible bud growth is inhibited. The length of the dormancy period is under environmental, physiological and hormonal control. Sucrose availability is one prerequisite for bud break. In the absence of sucrose, no bud break occurs. Thus, sucrose is likely to serve as nutrient and signal molecule at the same time. The mode of sucrose sensing is only vaguely understood, but most likely involves trehalose-6-phosphate and SnRK1 signalling networks. This conclusion is supported by the observation that ectopically manipulation of trehalose-6-phosphate levels influences the length of the dormancy period. Once physiological competence is achieved, Sprouting is controlled by the level of phytohormones. Two phytohormones, ABA and ethylene, are supposed to suppress Tuber Sprouting; however, the exact role of ethylene remains to be elucidated. Cytokinins and gibberellins are required for bud break and sprout growth, respectively. The fifth classical phytohormone, auxin, seems to play a role in vascular development. During the dormancy period, buds are symplastically isolated, which changes during bud break. In parallel to the establishment of symplastic connectivity, vascular tissue develops below the growing bud most likely to support the outgrowing sprout with assimilates mobilised in parenchyma cells. Sprouting leads to major quality losses of stored potato Tubers. Therefore, control of Tuber Sprouting is a major objective in potato breeding. Although comparative transcriptome analysis revealed a large number of genes differentially expressed in growing versus dormant buds, no master-regulator of potato Tuber Sprouting has been identified so far.
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Deoxyuridine triphosphatase expression defines the transition from dormant to Sprouting potato Tuber buds
Molecular Breeding, 2010Co-Authors: Melanie Senning, Uwe Sonnewald, Sophia SonnewaldAbstract:Identification of molecular markers defining the end of Tuber dormancy prior to visible Sprouting is of agronomic interest for potato growers and the potato processing industry. In potato Tubers, breakage of dormancy is associated with the reactivation of meristem function. In dormant meristems, cells are arrested in the G1/G0 phase of the cell cycle and re-entry into the G1 phase followed by DNA replication during the S phase enables bud outgrowth. Deoxyuridine triphosphatase (dUTPase) is essential for DNA replication and was therefore tested as a potential marker for meristem reactivation in Tuber buds. The corresponding cDNA clone was isolated from potato by PCR. The deduced amino acid sequence showed 94% similarity to the tomato homologue. By employing different potato cultivars, a positive correlation between dUTPase expression and onset of Tuber Sprouting could be confirmed. Moreover, gene expression analysis of Tuber buds during storage time revealed an up-regulation of the dUTPase 1 week before visible Sprouting occurred. Further analysis using an in vitro sprout assay supported the assumption that dUTPase is a good molecular marker to define the transition from dormant to active potato Tuber meristems.
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Expression of an Escherichia coli phosphoglucomutase in potato ( Solanum Tuberosum L.) results in minor changes in Tuber metabolism and a considerable delay in Tuber Sprouting
Planta, 2005Co-Authors: Anna Lytovchenko, Uwe Sonnewald, Lothar Willmitzer, Mohammad R. Hajirezaei, Ira Eickmeier, Volker Mittendorf, Alisdair R. FernieAbstract:The aim of this work was to evaluate the influence of elevating the cytosolic activity of phosphoglucomutase (PGM; EC 5.4.2.2) on photosynthesis, growth and heterotrophic metabolism. Here we describe the generation of novel transgenic plants expressing an Escherichia coli phosphoglucomutase (EcPGM) under the control of the 35S promoter. These lines were characterised by an accumulation of leaf sucrose, despite displaying no alterations in photosynthetic carbon partitioning, and a reduced Tuber starch content. Determinations of the levels of a wide range of other metabolites revealed dramatic reductions in maltose and other sugars in leaves of the transformants, as well as a modification of the pattern of organic and amino acid content in Tubers of these lines. Intriguingly, the transgenics also displayed a dramatically delayed rate of Sprouting and significantly enhanced rate of respiration, however, it is important to note that the severity of these traits did not always correlate with the level of transgene expression. These results are discussed in the context of current understanding of the control of respiration and the breaking of Tuber dormancy.
Guillaume Tcherkez - One of the best experts on this subject based on the ideXlab platform.
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Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid communications in mass spectrometry : RCM, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The delta(13)C (carbon isotope composition) variations in respired CO(2), total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly (13)C-depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were (13)C-enriched compared with source Tuber-sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against (12)C. However, both apparent fractionations were explained by the consumption of (13)C-depleted carbon for respiration or growth that enriched in the (13)C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly (13)C-depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
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Is there any 12 C/ 13 C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid Communications in Mass Spectrometry, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The δ13C (carbon isotope composition) variations in respired CO2, total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly 13C‐depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were 13C‐enriched compared with source Tuber‐sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against 12C. However, both apparent fractionations were explained by the consumption of 13C‐depleted carbon for respiration or growth that enriched in the 13C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly 13C‐depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
Florence Maunoury-danger - One of the best experts on this subject based on the ideXlab platform.
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Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid communications in mass spectrometry : RCM, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The delta(13)C (carbon isotope composition) variations in respired CO(2), total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly (13)C-depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were (13)C-enriched compared with source Tuber-sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against (12)C. However, both apparent fractionations were explained by the consumption of (13)C-depleted carbon for respiration or growth that enriched in the (13)C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly (13)C-depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
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Is there any 12 C/ 13 C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid Communications in Mass Spectrometry, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The δ13C (carbon isotope composition) variations in respired CO2, total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly 13C‐depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were 13C‐enriched compared with source Tuber‐sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against 12C. However, both apparent fractionations were explained by the consumption of 13C‐depleted carbon for respiration or growth that enriched in the 13C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly 13C‐depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
Sophia Sonnewald - One of the best experts on this subject based on the ideXlab platform.
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Impact of ISA silencing on Tuber Sprouting.
2017Co-Authors: Stephanus J. Ferreira, Sophia Sonnewald, Melanie Senning, Michaela Fischer-stettler, Sebastian Streb, Michelle Ast, Ekkehard H. Neuhaus, Samuel C. Zeeman, Uwe SonnewaldAbstract:Tubers of 5 plants each from wild type (WT) and transgenic lines 7, 16 and 39 were stored after harvest at room temperature in darkness. A) Sprouting kinetics. To monitor the impact on dormancy length, 2–5 similar sized Tubers from each plant were picked (n = 13–20) and their Sprouting behaviour was regularly scored over a 15-week period until 100% Sprouting had been reached in wild-type Tubers. A Tuber was considered to sprout when sprouts of 2 mm length became visible. B) Photographs of transgenic (lines 7, 16, 39) and control Tubers taken after 13 weeks of storage showing that the transgenic lines sprout earlier than the wild-type controls (WT). C) Number of sprouts per Tuber. Number of sprouts formed per Tuber were counted from 13–20 individual Tubers. Values represent the mean +/- SE. Significant differences to wild type were calculated using two-tailed t-test assuming equal variances and are indicated by asterisks (**p
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Regulation of potato Tuber Sprouting
Planta, 2014Co-Authors: Sophia Sonnewald, Uwe SonnewaldAbstract:Following Tuber induction, potato Tubers undergo a period of dormancy during which visible bud growth is inhibited. The length of the dormancy period is under environmental, physiological and hormonal control. Sucrose availability is one prerequisite for bud break. In the absence of sucrose, no bud break occurs. Thus, sucrose is likely to serve as nutrient and signal molecule at the same time. The mode of sucrose sensing is only vaguely understood, but most likely involves trehalose-6-phosphate and SnRK1 signalling networks. This conclusion is supported by the observation that ectopically manipulation of trehalose-6-phosphate levels influences the length of the dormancy period. Once physiological competence is achieved, Sprouting is controlled by the level of phytohormones. Two phytohormones, ABA and ethylene, are supposed to suppress Tuber Sprouting; however, the exact role of ethylene remains to be elucidated. Cytokinins and gibberellins are required for bud break and sprout growth, respectively. The fifth classical phytohormone, auxin, seems to play a role in vascular development. During the dormancy period, buds are symplastically isolated, which changes during bud break. In parallel to the establishment of symplastic connectivity, vascular tissue develops below the growing bud most likely to support the outgrowing sprout with assimilates mobilised in parenchyma cells. Sprouting leads to major quality losses of stored potato Tubers. Therefore, control of Tuber Sprouting is a major objective in potato breeding. Although comparative transcriptome analysis revealed a large number of genes differentially expressed in growing versus dormant buds, no master-regulator of potato Tuber Sprouting has been identified so far.
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Deoxyuridine triphosphatase expression defines the transition from dormant to Sprouting potato Tuber buds
Molecular Breeding, 2010Co-Authors: Melanie Senning, Uwe Sonnewald, Sophia SonnewaldAbstract:Identification of molecular markers defining the end of Tuber dormancy prior to visible Sprouting is of agronomic interest for potato growers and the potato processing industry. In potato Tubers, breakage of dormancy is associated with the reactivation of meristem function. In dormant meristems, cells are arrested in the G1/G0 phase of the cell cycle and re-entry into the G1 phase followed by DNA replication during the S phase enables bud outgrowth. Deoxyuridine triphosphatase (dUTPase) is essential for DNA replication and was therefore tested as a potential marker for meristem reactivation in Tuber buds. The corresponding cDNA clone was isolated from potato by PCR. The deduced amino acid sequence showed 94% similarity to the tomato homologue. By employing different potato cultivars, a positive correlation between dUTPase expression and onset of Tuber Sprouting could be confirmed. Moreover, gene expression analysis of Tuber buds during storage time revealed an up-regulation of the dUTPase 1 week before visible Sprouting occurred. Further analysis using an in vitro sprout assay supported the assumption that dUTPase is a good molecular marker to define the transition from dormant to active potato Tuber meristems.
Camille Bathellier - One of the best experts on this subject based on the ideXlab platform.
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Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid communications in mass spectrometry : RCM, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The delta(13)C (carbon isotope composition) variations in respired CO(2), total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly (13)C-depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were (13)C-enriched compared with source Tuber-sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against (12)C. However, both apparent fractionations were explained by the consumption of (13)C-depleted carbon for respiration or growth that enriched in the (13)C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly (13)C-depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
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Is there any 12 C/ 13 C fractionation during starch remobilisation and sucrose export in potato Tubers?
Rapid Communications in Mass Spectrometry, 2009Co-Authors: Florence Maunoury-danger, Camille Bathellier, Julien Laurette, Chantal Fresneau, Jaleh Ghashghaie, Claire Damesin, Guillaume TcherkezAbstract:The δ13C (carbon isotope composition) variations in respired CO2, total organic matter, proteins, sucrose and starch have been measured during Tuber Sprouting of potato (Solanum Tuberosum) in darkness. Measurements were carried out both on Tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly 13C‐depleted compared with starch in Tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were 13C‐enriched compared with source Tuber‐sucrose, suggesting that sucrose translocation from Tuber to sprouts fractionated against 12C. However, both apparent fractionations were explained by the consumption of 13C‐depleted carbon for respiration or growth that enriched in the 13C sucrose molecules left behind. In addition, whole Tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly 13C‐depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
