Glutamine Synthetase Regulation by Energy Charge in Sunflower Roots

Weissman, Gerard S.

doi:10.1104/pp.57.3.339

Cited by 40 publications

(9 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…GS, as an enzyme utilizing the energy of the anhydride phosphate bond in a synthetic reaction, might thus be expected to be influenced by the energy charge of the cell. All data of the present study confirm the findings of previous studies with sunflower roots (34) indicating a direct correlation between energy charge and GS activity (Figs. 1-4).…”

Section: Discussionsupporting

confidence: 83%

“…The high degree of correlation between GS activity and the energy level of sunflower root tissue noted in a previous study (34) was also found in the present investigation. For both entrainment and continuous light free-running periods, L12:D12 plants subjected to a 6 AM on-6 PM off regimen displayed a rhythm of approximately 12 h for energy charge that was directly correlated in time with the rhythmic activity of GS (Fig.…”

Section: Methodssupporting

confidence: 75%

“…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) ([ATP]…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

Knight

Weissman²

1982

Plant Physiol.

Self Cite

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

Section: Discussionsupporting

confidence: 83%

Section: Methodssupporting

confidence: 75%

mentioning

confidence: 99%

See 1 more Smart Citation

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

Knight

Weissman²

1982

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…As shown in Table II, assimilation of inorganic N was much affected by NaCl, an observation which is consistent with results of Helal and Mengel (5) obtained from young barley plants. This effect is related to glutamine synthase, whose activity depends much on energy supply (19).…”

Section: Discussionmentioning

confidence: 99%

Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO₂ Assimilation, and Photosynthate Conversion in Young Broad Beans

Helal¹,

Mengel²

1981

Plant Physiol.

View full text Add to dashboard Cite

MATERIALS AND METHODS Seedlings of Viiafaba were grown for four weeks at two different light intensities (55 and 105 watts per square meter) in a saline (50 millimlar NaCI) and nonsaline nutrient solution. NaCi salinity depressed growth and restricted protein formation, CO2 assimilation, and especially the incorporation of photosynthates into the lipid fraction. Conversion of photosynthates in leaves was much more affected by salinity than was photosynthate turnover in roots. The detrimental effect of NaCi salinity on growth, protein formation, and CO2 assimilation was greater under low than under high light conditions. Plants of the high light intensity treatment were more capable of excluding Na+ and Cl and accumulating nutrient cation species (Ca2 , K+, Mg2e) than plants grown under low light intensity. It is suggested that the improved ionic status provided better conditions for protein synthesis, CO2 assimilation, and especially for the conversion of photosynthates into lipids.Saline conditions depress the growth rate of many plant species. Salinity also influences various biochemical processes such as the assimilation of N, protein synthesis, and CO2 assimilation (1, 4, 14, 15, During the first week of cultivation the solution was diluted to fifth and in the second week to half strength. In addition to these nutrients, NaCl also was added at two concentrations: I mM, control treatment; and 50 mm, salinization treatment. A concentration of 1 mm NaCl was chosen for the control treatment, because under field conditions some Na+ and Cl-always is present in the soil solution. Such a low NaCl level has no salinity effect. Plants in both of these treatments were exposed to two light intensities: 55 w/m2 and 105 w/m2. The experiment thus consisted of a 2 x 2 factorial design. Each treatment comprised four 5 x 1 pots with five plants per pot. NaCl was added gradually after the first week ofgrowth. On each day 10 mmol NaCl/l was introduced into the nutrient solution until the final level of 50 mm. The pH of the nutrient solutions ranged from 5.2 to 5.8. The nutrient solutions were continuously aerated and were completely renewed every fourth day. The plants were grown in growth chambers supplying the following environmental conditions: 14 h light, day temperature 24 C, night temperature 14 C, air humidity 70%.Twenty-seven days after germination one plant was harvested from each pot (four replications per treatment) and divided into leaves, stems, and roots. These were weighed, cut, and then subdivided. One subsample was oven-dried for the determination of the dry matter content. In this subsample the minerals were analyzed. In the other subsample the N fractions were analyzed according to a technique described by Helal et al. (4). As the effect of salinity on the N fractions did not differ much for leaves, stems, and roots, the N contents were recalculated on a total plant matter basis (Table II). The effect of salinity on the mineral content was especially evident in the leaves and for this reason only ...

show abstract

“…GS is associated with chloroplasts and requires ATP in order to assimilate ammonium. The enzyme is known to be especially sensitive to small changes in adenylate energy charge (25,26), and, in this scheme, ATP is supplied to the enzyme by photophosphorylation. When the cell is not light limited, sufficient ATP supply is maintained for high GS activity.…”

Section: Introductionmentioning

confidence: 99%

Light-Shade Adaptation in Marine Phytoplankton

Falkowski

1980

Primary Productivity in the Sea

412

309

View full text Add to dashboard Cite

Glutamine Synthetase Regulation by Energy Charge in Sunflower Roots

Cited by 40 publications

References 24 publications

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

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

Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO₂ Assimilation, and Photosynthate Conversion in Young Broad Beans

Light-Shade Adaptation in Marine Phytoplankton

Contact Info

Product

Resources

About

Glutamine Synthetase Regulation by Energy Charge in Sunflower Roots

Cited by 40 publications

References 24 publications

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

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

Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO2 Assimilation, and Photosynthate Conversion in Young Broad Beans

Light-Shade Adaptation in Marine Phytoplankton

Contact Info

Product

Resources

About

Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO₂ Assimilation, and Photosynthate Conversion in Young Broad Beans