The influence of exogenously supplied sucrose on glutamine synthetase and glutamate dehydrogenase levels in excisedPisum sativum roots

Sahulka, J.; Lisá, Ludmila

doi:10.1007/bf02923349

Cited by 18 publications

(18 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The syringes were then allowed to thaw to 5°C and the samples were crushed with the piston. Five to 20 ,uL of root juice extract were taken and diluted to 50 ,uL in an Eppendorf tube for osmolarity determination. Osmolarity was measured with a precalibrated micro-osmometer (Roebling 1 -DR).…”

Section: Osmolarity Of Root Tip Cellmentioning

confidence: 99%

“…However, it is now known that carbohydrate starvation is common in most higher plants. Indeed, microbial, insect, or herbivore attacks or reduction in light intensity or temperature may cause a substantial decrease in photosynthesis, and thus lead to starvation.Since the end of the seventies, carbohydrate starvation has been studied in a number of plant species: wheat (28, 29), maize (14, 18), barley (8), pearl millet (1), pea (20,26,27), soybean (13, 25), sycamore (7, 10, 12, 17), etc. These studies have shown that in most cases, sugar starvation triggers the following sequence in plant cells: (a) the depletion of intracellular carbohydrate content and the subsequent decrease of respiration (1,12,18,20,25); (b) the breakdown of lipids and proteins (1,7,12,28) and a decline in the respiratory quotient from 1 to 0.75 (18); (c) an increase in inorganic phosphate ( 12,17), phosphorylcholine (7, 17), and free amino acids (10), and a concomitant decline in nucleotides (17, 18) and glycolytic enzymatic activities (12); and (d) the more or less marked disappearance of some cell ultrastructures (1, 29).…”

mentioning

confidence: 99%

“…These studies have shown that in most cases, sugar starvation triggers the following sequence in plant cells: (a) the depletion of intracellular carbohydrate content and the subsequent decrease of respiration (1,12,18,20,25); (b) the breakdown of lipids and proteins (1,7,12,28) and a decline in the respiratory quotient from 1 to 0.75 (18); (c) an increase in inorganic phosphate ( 12,17), phosphorylcholine (7,17), and free amino acids (10), and a concomitant decline in nucleotides (17,18) and glycolytic enzymatic activities (12); and (d) the more or less marked disappearance of some cell ultrastructures (1,29).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Study of Glucose Starvation in Excised Maize Root Tips

Brouquisse¹,

James²,

Raymond³

et al. 1991

Plant Physiol.

161

159

View full text Add to dashboard Cite

Excised maize (Zea mays) root tips were used to follow the effects of a prolonged glucose starvation. Respiration rate began to decrease immediately after excision, reaching 30 to 40% of its initial value after 20 hours, and then declined more slowly until death of the tissues, which occurred after 200 hours of starvation. During the whole process, respiration could be uncoupled by 2,4-dinitrophenol and the energy charge remained high. These results suggest that in excised maize root tips, respiration rate is essentially limited by the rate of biosyntheses (ATP-utilizing processes) rather than mitochondrial number. Carbohydrates are the main respiratory substrates for plants, furnishing the malate and the acetyl-CoA necessary for the functioning of the Krebs cycle. Fifteen years ago it was still considered that, during the day, photosynthesis allowed starch synthesis in such amounts that the plant, particularly the root system, was never deprived of sugars. However, it is now known that carbohydrate starvation is common in most higher plants. Indeed, microbial, insect, or herbivore attacks or reduction in light intensity or temperature may cause a substantial decrease in photosynthesis, and thus lead to starvation.Since the end of the seventies, carbohydrate starvation has been studied in a number of plant species: wheat (28, 29), maize (14, 18), barley (8), pearl millet (1), pea (20,26,27), soybean (13, 25), sycamore (7, 10, 12, 17), etc. These studies have shown that in most cases, sugar starvation triggers the following sequence in plant cells: (a) the depletion of intracellular carbohydrate content and the subsequent decrease of respiration (1,12,18,20,25); (b) the breakdown of lipids and proteins (1,7,12,28) and a decline in the respiratory quotient from 1 to 0.75 (18); (c) an increase in inorganic phosphate ( 12,17), phosphorylcholine (7, 17), and free amino acids (10), and a concomitant decline in nucleotides (17, 18) and glycolytic enzymatic activities (12); and (d) the more or less marked disappearance of some cell ultrastructures (1, 29).The origin of the respiratory decrease during starvation was first attributed to carbohydrate depletion, by way of limitation of the substrate either for respiration or for biosynthetic processes; however, some experiments showed that root respiration rate was not a simple function ofcarbohydrate supply (8). Journet and co-workers (12) reported that during starvation the decrease in uncoupled respiration of sycamore cells was attributable to a progressive decrease in the number of mitochondria per cell; these authors concluded that the availability of respiratory substrates for the mitochondria does not determine the respiration rate of starved cells.In the present work, we investigated changes in 02 consumption, different organic compounds (sugars, fatty acids, proteins, adenine nucleotides), enzyme activities, and physical parameters (fresh and dry weight, osmolarity) in excised maize (Zea mays) root tips from the beginning of glucose starvation to tissue dea...

show abstract

Section: Osmolarity Of Root Tip Cellmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Study of Glucose Starvation in Excised Maize Root Tips

Brouquisse¹,

James²,

Raymond³

et al. 1991

Plant Physiol.

161

159

View full text Add to dashboard Cite

show abstract

“…in common wheat (Wittenbach 1977, Wittenbach et al 1982, maize (Saglio andPradet 1980, Pace et al 1990), barley (Farrar 1981), pearl millet (Baysdorfer et al 1988), pea (Webster and van't Hof 1973, Sahulka and Lisa 1978, Webster and Henry 1987, Morkunas et al 1999, 2000, soybean (Kerr et al 1985, Walsh et al 1987, sycamore (Journet et al 1986, Dorne et al 1987, Genix et al 1990), tobacco (Moriyasu and Ohsumi 1996), lupine (Morkunas et al 1999, Borek and Ratajczak 2002, Morkunas et. al.…”

Section: Materials and Methods Of Research On Sugar Starvationmentioning

confidence: 99%

Plant Responses to Sugar Starvation

Morkunas¹,

Borek²,

Formela³

et al. 2012

Carbohydrates - Comprehensive Studies on Glycobiology and Glycotechnology

View full text Add to dashboard Cite

“…These observations, when considered together with the precautions taken in the present study aimed at preventing exposure of the root system to fluctuations of light and darkness, lead to the conclusion that the root GS rhythms reported here are ultimately dependent upon processes in the leaf such as photosynthesis and/or phytochrome activation of a Zeitgeber (7). The association of root rhythms with these processes could be mediated by shoot-to-root translocation of carbohydrate, substances known to affect GS activity (28). However, to date no firm evidence for rhythmic changes in the translocation of carbohydrate or in the concentration of respirable materials in roots has been presented.…”

Section: Discussionmentioning

confidence: 99%

Rhythms in Glutamine Synthetase Activity, Energy Charge, and Glutamine in Sunflower Roots

Knight

Weissman²

1982

Plant Physiol.

View full text Add to dashboard Cite

Roots of sunflower plants (Helianthus anus L. var. Mammoth Russian) subjected to ,12:D12, L18:D6, and L12:D12 followed by continuous light all display rhythms of about 12 hours for glutamine synthetase (GS) activity (transferase reaction) with one peak in the 'light phase' and one in the 'dark phase.' Root energy charge (EC = ATP+%ADP/ ATP+ADP+AMP) is directly correlated with GS, but the GS rhythm is better explained as the result of a rhythmic adenine nucleotide ratio (ATP/ ADP+AMP) that regulates enzyme activity through allosteric modification. When L12:D12 plants are subjected to free-running conditions in continuous darkness, only diurnal rhythms for GS and EC, with peaks in the dark phase, remain. The 12-hour root rhythms for GS and EC appear to be composed of two alternating rhythms, one a diurnal, light-dependent, incompletely circadian light phase rhythm and the other a light-independent, circadian dark phase rhythm.Only glutamine, of the root amino acids, displays cyclical changes in concentration, maintaining under all conditions a 12-hour rhythm that is consistently synchronized with, but nearly always inversely correlated with, GS and EC rhythms.The phenomenon of endogenous biological oscillation in plants has been found to occur at all levels of organization: organ, cells, organelle, and enzyme (7). Almost universally, the light:dark regimen has been identified as the entraining factor and numerous examples of light-entrainable rhythms have been reported for physiological or biochemical processes in higher plants (14). Most rhythms appear to be circadian with periodicities under freerunning conditions ofapproximately 24 h. Also reported, however, are rhythms with a period clearly less than 24 h and these have been termed 'ultradian' (10). In view of the correlation demonstrated in this laboratory (34) between the activity of sunflower root GS3 and energy charge as defined by Atkinson (2) investigation in which an effort has been made to determine whether energy charge and GS vary in a cyclical manner in sunflower roots, a portion of the plant not expected to be directly affected by light functioning as a 'Zeitgeber.' In view of the fact that previous studies have indicated a role for amino acids in the regulation of higher plant GS (22, 27), we have also examined variations in the concentrations of these substances in sunflower roots with respect to rhythmicity. MATERIALS AND METHODSPlant Culture. Sunflower seeds (Helianthus annus L. var. Mammoth Russian) were germinated in vermiculite in a controlled temperature chamber (26-27°C) under artificial light with a light:dark regimen specific to a particular experiment (L12:D12, L18:D6). Eight-d-old seedlings were transferred to a previously described (35) continuous flow apparatus that provided enclosure of the root system in blackened tubes. Complete culture solution containing nitrogen as 10 mm NO3 was allowed to pass over the roots for the remainder of the growth period. On day 28, the plants, having previously been subjected to a specific l...

show abstract

The influence of exogenously supplied sucrose on glutamine synthetase and glutamate dehydrogenase levels in excisedPisum sativum roots

Cited by 18 publications

References 9 publications

Study of Glucose Starvation in Excised Maize Root Tips

Study of Glucose Starvation in Excised Maize Root Tips

Plant Responses to Sugar Starvation

Rhythms in Glutamine Synthetase Activity, Energy Charge, and Glutamine in Sunflower Roots

Contact Info

Product

Resources

About