Study of Glucose Starvation in Excised Maize Root Tips

Brouquisse, Renaud; James, Franck; Raymond, Philippe; Pradet, A.

doi:10.1104/pp.96.2.619

Cited by 161 publications

(187 citation statements)

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“…Maize (Zea mays L. cv DEA; Pioneer France, MaTs, France) seeds were germinated for 3 d in the dark at 25°C as described by Brouquisse et al (1991). The 3-mm tips of primary roots were excised and treated in three steps differing by Glc supply.…”

Section: Plant Materials and Treatmentsmentioning

confidence: 99%

“…The first two steps of prestarvation and Glc feeding were essentially as described by DieuaideNoubhani et al (1995). Briefly, prestarvation was for 4 h in a medium containing various minerals but no sugars (see Brouquisse et al, 1991) called medium A. Glc refeeding was by transfer to the same medium supplemented with either labeled or unlabeled 200 mM Glc for different periods of time. The third step of treatment was starvation for up to 20 h by incubation in medium A.…”

Section: Plant Materials and Treatmentsmentioning

confidence: 99%

“…Similar effects of sugar starvation on metabolism have been observed in different plant materials, such as maize (Zea mays L.) root tips, asparagus spears, Acev spp., or cucumber cells, and in dark-senescing leaves. For example, the respiration rate declines because of a decrease in the demand for ATP rather than a limitation by the substrate (Brouquisse et al, 1991); the respiratory quotient declines from 1 to 0.75 (Saglio et al, 1980;Brouquisse et al, 1991); and total proteins and lipids decrease, whereas Asn accumulates (Genix et al, 1990; Brouquisse et al, 1992, and refs. therein), indicating that proteins and lipids replace carbohydrates as respiratory substrates.…”

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Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips

1997

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Excised maize (Zea mays L.) root tips were used to study the early metabolic effects of glucose (Clc) starvation. Root tips were prelabeled with [1-'3ClClc so that carbohydrates and metabolic intermediates were close to steady-state labeling, but lipids and proteins were scarcely labeled. They were then incubated in a sugardeprived medium for carbon starvation. Changes in the level of soluble sugars, the respiratory quotient, and the 13C enrichment of intermediates, as measured by 13C and 'H nuclear magnetic resonance, were studied to detect changes in carbon fluxes through glycolysis and the tricarboxylic acid cycle. Labeling of glutamate carbons revealed two major changes in carbon input into the tricarboxylic acid cycle: (a) the phosphoenolpyruvate carboxylase flux stopped early after the start of Clc starvation, and (b) the contribution of glycolysis as the source of acetyl-coenzyme A for respiration decreased progressively, indicating an increasing contribution of the catabolism of protein amino acids, fatty acids, or both. The enrichment of glutamate carbons gave no evidence for proteolysis in the early steps of starvation, indicating that the catabolism of proteins was delayed compared with that of fatty acids. Labeling of carbohydrates showed that sucrose turnover continues during sugar starvation, but gave no indication for any significant flux through gluconeogenesis.In the last few years, various works have established that the supply of carbohydrates to nongreen plant cells is variable and controls a number of the cell's activities, including gene expression and basal metabolism (for review, see Koch, 1996). Similar effects of sugar starvation on metabolism have been observed in different plant materials, such as maize (Zea mays L.) root tips, asparagus spears, Acev spp., or cucumber cells, and in dark-senescing leaves. For example, the respiration rate declines because of a decrease in the demand for ATP rather than a limitation by the substrate (Brouquisse et al., 1991); the respiratory quotient declines from 1 to 0.75 (Saglio et al., 1980;Brouquisse et al., 1991); and total proteins and lipids decrease, whereas Asn accumulates (Genix et al., 1990; Brouquisse et al., 1992, and refs. therein), indicating that proteins and lipids replace carbohydrates as respiratory substrates.Various enzymatic activities change in a coordinated way. Those linked with carbohydrate metabolism decrease,

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Section: Plant Materials and Treatmentsmentioning

confidence: 99%

Section: Plant Materials and Treatmentsmentioning

confidence: 99%

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confidence: 99%

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Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips

1997

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“…Moreover, in most plant tissues other than the rice coleoptile, NO 3 -reduction under and assayed spectrophotometrically in sample extracts using the phenol-hypochlorite method. 42 Enzyme assays. Nitrate and nitrite reductase.…”

Section: Plant Development and Biomass Allocationmentioning

confidence: 99%

Prolonged root hypoxia effects on enzymes involved in nitrogen assimilation pathway in tomato plants

Horchani

Aschi‐Smiti²

2010

Plant Signaling & Behavior

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IntroductionPlants grow in a dynamic environment, which frequently imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding is one of the most significant abiotic stresses. 1 Flooding of the soil can have a tremendous impact on the growth and survival of plants, and thereby on agricultural as well as natural ecosystems. In the last decades considerable progress has been made in our understanding of the mechanisms that enable certain plant species and cultivars to withstand periods with excess soil water or even complete submergence. Much of the research has been carried out with crop plant species, such as Oryza sativa, Zea mays, Trifolium subterraneum and Medicago sativa, 2-5 but wild species originating from wetland habitats have been also used, mostly for comparative studies. 6,7 With transient flooding or irrigation followed by slow drainage, or in natural wetlands, plant roots can become oxygen deficient because of slow transfer of dissolved oxygen in the waterfilled pore space of the soil. The decrease in ambient oxygen may not be, itself or alone, the perceived signal but could trigger metabolic responses, which then initiate the signalling cascade. 8 The immediate consequence of oxygen depletion is the reduction in respiration, thus diminishing ATP generation, and leading to a decrease in the ATP/ADP ratio and the adenylate energy charge. 9 In order to investigate the effects of root hypoxia (1-2% oxygen) on the nitrogen (N) metabolism of tomato plants (Solanum lycopersicum L. cv. Micro-Tom), a range of N compounds and N-assimilating enzymes were performed on roots and leaves of plants submitted to root hypoxia at the second leaf stage for three weeks. Obtained results showed that root hypoxia led to a significant decrease in dry weight (DW) production and nitrate content in roots and leaves. conversely, shoot to root DW ratio and nitrite content were significantly increased. contrary to that in leaves, glutamine synthetase activity was significantly enhanced in roots. The activities of nitrate and nitrite reductase were enhanced in roots as well as leaves. The higher increase in the Nh 4 + content and in the protease activities in roots and leaves of hypoxically treated plants coincide with a greater decrease in soluble protein contents. Taken together, these results suggest that root hypoxia leaded to higher protein degradation. The hypoxia-induced increase in the aminating glutamate dehydrogenase activity may be considered as an alternative N assimilation pathway involved in detoxifying the Nh 4 + , accumulated under hypoxic conditions. With respect to hypoxic stress, the distinct sensitivity of the enzymes involved in N assimilation is discussed. and 0.13 ± 0.03 g, respectively. The changes in the root and shoot dry weights (DW) and in shoot/root ratio were investigated after a three week period of hypoxic treatment. Root hypoxia decreased root and leaf DW production by 34 and 18%, respectively. Shoot to root DW ratio increas...

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“…In the second experiment, soluble carbohydrates were extracted according to Brouquisse et al, (1991) and the enzymatic analysis followed the method of Kunst et al (1984).…”

Section: Measurement Of Leaf Mass Per Unit Area and Analysis Of Carbomentioning

confidence: 99%

Contribution of carbohydrate pools to the variations in leaf mass per area within a tomato plant

Bertin¹,

Tchamitchian²,

Baldet³

et al. 1999

New Phytologist

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The contribution of the starch and soluble carbohydrate pools to the diurnal variations of leaf mass per unit area (LMA) has been investigated in tomato leaves. A glasshouse experiment was carried out with plants pruned to two or five fruits per truss. Leaflets were sampled at sunrise, noon and sunset at different positions within the leaf (basal or terminal), and on different sympods along the stem. Carbohydrate contents and LMA were significantly higher in the terminal than in the basal leaflets, except at sunrise. During the day, differences in starch accumulation between terminal and basal leaflets increased with leaf height on the plant. Among sympods, the soluble carbohydrate content of the terminal leaflets did not vary significantly, whereas at 13.00 h the LMA was minimum in the middle of the plant and maximum at the top, and the leaf starch content significantly increased half-way up the plant. The plant fruit load had only small and non-significant effects on the LMA and carbohydrate contents. The response of LMA and carbohydrate contents to changing source activity was observed under controlled climatic conditions. The starch pool of fully expanded leaves was rapidly filled and emptied under increasing and decreasing source activity. In young expanding leaves, this pool was hardly filled during daylight. On average the soluble carbohydrates did not contribute significantly to the diurnal variations in LMA, whereas fluctuations in starch explained c. 70% and 44% of these variations in the upper and lower leaves, respectively. The results are discussed with respect to the modelling of LMA at the level of individual tomato leaves or sympods.

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Study of Glucose Starvation in Excised Maize Root Tips

Cited by 161 publications

References 24 publications

Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips

Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips

Prolonged root hypoxia effects on enzymes involved in nitrogen assimilation pathway in tomato plants

Contribution of carbohydrate pools to the variations in leaf mass per area within a tomato plant

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