An <i>Arabidopsis</i> mutant showing reduced feedback inhibition of photosynthesis

Oosten, Jean-Jacques M. Van; Gerbaud, Alain; Huijser, Casper; Dijkwel, Paul P.; Chua, Nam‐Hai; Smeekens, Sjef

doi:10.1046/j.1365-313x.1997.12051011.x

Cited by 49 publications

(47 citation statements)

References 31 publications

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“…The availability of the sugar-signaling sun6 mutant, which was previously isolated in our laboratory (Dijkwel et al, 1997), allowed us to further test whether Man blocks germination via a HXK-mediated process. sun6 was isolated for its insensitivity to Suc, a disaccharide that can readily be converted to Glc and Fru, both of which are HXK substrates.…”

Section: Discussionmentioning

confidence: 99%

“…Photosynthesis and expression of photosynthesis genes show a reduced sensitivity to repression by the Glc analog 2-deoxyglucose in sun6 compared with the wild type. Seedling development in this mutant has also been found to be insensitive to high concentrations of Glc (Van Oosten et al, 1997), and Van Oosten et al (1997) proposed that the sun6 mutation affects a process involved in the HXK-mediated signal transduction pathway. When tested for its capacity to germinate on Man, we found that sun6 displays a significantly greater insensitivity to this Glc analog than the wild type.…”

Section: Discussionmentioning

confidence: 99%

“…Although Suc is a disaccharide, it can readily be converted to Glc and Fru, both of which are HXK substrates. Van Oosten et al (1997) showed that in sun6 photosynthesis is no longer repressed by the Glc analog 2-deoxyglucose, and that sun6 seedling development is insensitive to high Glc concentrations that arrest development in wild-type seedlings. They proposed that the sun6 mutation affects a process involved in the HXK-mediated signal transduction pathway.…”

Section: Germination Of Sun6 On Manmentioning

confidence: 99%

“…We developed a screening strategy for the isolation of sugar-sensing mutants, and isolated a number of sun (Suc uncoupled) mutants (Dijkwel et al, 1996(Dijkwel et al, , 1997Smeekens and Rook, 1997;Van Oosten et al, 1997). During the char-acterization of these mutants, germination on several different sugars was tested.…”

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Mannose Inhibits Arabidopsis Germination via a Hexokinase-Mediated Step1

1999

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Low concentrations of the glucose (Glc) analog mannose (Man) inhibit germination of Arabidopsis seeds. Man is phosphorylated by hexokinase (HXK), but the absence of germination was not due to ATP or phosphate depletion. The addition of metabolizable sugars reversed the Man-mediated inhibition of germination. Carbohydrate-mediated regulation of gene expression involving a HXK-mediated pathway is known to be activated by Glc, Man, and other monosaccharides. Therefore, we investigated whether Man blocks germination through this system. By testing other Glc analogs, we found that 2-deoxyglucose, which, like Man, is phosphorylated by HXK, also blocked germination; no inhibition was observed with 6-deoxyglucose or 3-O-methylglucose, which are not substrates for HXK. Since these latter two sugars are taken up at a rate similar to that of Man, uptake is unlikely to be involved in the inhibition of germination. Furthermore, we show that mannoheptulose, a specific HXK inhibitor, restores germination of seeds grown in the presence of Man. We conclude that HXK is involved in the Man-mediated repression of germination of Arabidopsis seeds, possibly via energy depletion.Among the many regulatory systems and signals in plants, carbon-metabolite-mediated gene regulation has been receiving growing attention in the past few years (for reviews, see

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Germination Of Sun6 On Manmentioning

confidence: 99%

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Mannose Inhibits Arabidopsis Germination via a Hexokinase-Mediated Step1

1999

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“…This transient increase in PC mRNA and luciferase activity levels can be repressed by SUC. Mutants defective in SUC repression were identified on the basis of high luminescence levels when grown on plates with 3% SUC (Dijkwel et al, 1997). Such Suc-mcoupled (sun) mutants show no or reduced SUC repression of luminescence.…”

Section: Sugar-sensing Mutantsmentioning

confidence: 99%

Sugar Sensing and Sugar-Mediated Signal Transduction in Plants

Smeekens

Rook²

1997

Plant Physiology

562

577

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Information concerning the sugar status of plant cells is of great importance during a11 stages of the plant life cycle. The availability of or lack of sugars triggers many metabolic and developmental responses, and it is not surprising, therefore, that sugars profoundly affect the expression of a large number of genes (for review, see Koch, 1996;Graham, 1996). Sugar sensing occurs at the level of individual cells and the responses of such cells must be integrated at the tissue, organ, and plant level. Therefore, sugar-induced signals will interact with other sensing and signaling pathways. The mechanisms used by plant cells to sense sugars and to process this information are essentially unknown, and only recently are these questions being addressed experimentally. This lack of knowledge contrasts with the situation in yeast and bacteria, in which the molecular and physiological analysis of mutants have yielded extensive information about sugar perception (Trumbly, 1992;Ronne, 1995;Saier et al., 1995). SUGAR SENSING IN YEAST A N D ANIMALSYeast (Sacckauomyces ceuevisiae) serves as a model for investigating many basic biological questions about eukaryotes and is also an important paradigm for sugar sensing in plants. In yeast the availability of the preferred sugar substrate Glc signals the Glc repression phenomenon (for review, see Trumbly, 1992;Ronne, 1995;Thevelein and Hohmann, 1995). Glc repression dramatically alters yeast intermediary carbohydrate metabolism such that only Glc is being used as a carbon source, despite the presence of other readily accessible carbon sources. Glc is converted into Glu-6-P by HXK and is further metabolized via glycolysis. Genes involved in the metabolism of other carbon substrates are switched off, as are genes encoding key steps in gluconeogenic metabolism. A number of yeast mutants that are impaired in aspects of the Glc repression phenomenon have been isolated and their analysis has provided insight into the complexity of sugar sensing and signaling pathways. From these studies it was concluded that the Glc-phosphorylating enzyme HXK2 is a major Glc sensor responsible for sus- tained Glc repression. HXK2 activity initiates a signal transduction pathway that involves a number of different gene products (Fig. 1) and results in the repression of a large set of genes. Thus, the entry of Glc into glycolytic metabolism as mediated by HXK2 is a key step in Glc sensing.In the repression pathway the function of two protein complexes has been elucidated. These are the GLC7 type 1 protein phosphatase complex (Tu and Carlson, 1995, and refs. therein) and the SSN6/TUP1 complex, which functions as a general repressor of transcription through modulation of chromatin structure. Binding of the SSN6/TUP1 complex to specific sites is directed by the DNA-binding protein MIG1, and in this way genes that contain MIG1-binding sites are repressed. Exactly how the HXK2, GLC7, and SSNG/TUPl /MIG1 complexes are connected is unknown. For example, in the repression pathway no substrates for the REG1 ...

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Crop Models

Singels

2013

Sugarcane: Physiology, Biochemistry, and Functional Biology

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This chapter reviews the mathematical modeling of crop development, growth, and yield and its application in research and management of sugarcane production. Generic concepts for modeling key aspects of the soil-plant-atmosphere system are reviewed. The main process-based sugarcane models are then reviewed with respect to concepts, simulation accuracy, and application in research and management. The extent to which these models represent knowledge of sugarcane physiology is assessed. Functional and empirical models for predicting sugarcane yield and resource use are also briefly reviewed. Last, the potential of processbased models for enhancing crop improvement is explored by studying examples of other crops and highlighting the modeling requirements for this application. ABBREVIATION LIST

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An Arabidopsis mutant showing reduced feedback inhibition of photosynthesis

Cited by 49 publications

References 31 publications

Mannose Inhibits Arabidopsis Germination via a Hexokinase-Mediated Step1

Mannose Inhibits Arabidopsis Germination via a Hexokinase-Mediated Step1

Sugar Sensing and Sugar-Mediated Signal Transduction in Plants

Crop Models

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