Nitrogen and metabolic regulation of the expression of plastidic glutamine synthetase in alfalfa (Medicago sativa)

Zozaya-Hinchliffe, Marcela; Potenza, Carol; Ortega, J. L. Araus; Sengupta‐Gopalan, Champa

doi:10.1016/j.plantsci.2004.12.001

Cited by 20 publications

(11 citation statements)

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“…In all cases a significant drop (about tenfold) in the hybridization signal was seen in all the plants treated with KNO 3 . The GS 2 probe, however, showed more than a twofold higher hybridization signal in the plants treated with KNO 3 (control and transgenic) than in the plants fed with KCl, coincidental with the role of GS 2 in the assimilation of ammonia produced by the reduction of nitrate (Zozaya‐Hinchliffe et al. , 2005).…”

Section: Resultsmentioning

confidence: 88%

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The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa

et al. 2006

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SummaryHigher plants assimilate nitrogen in the form of ammonia through the concerted activity of glutamine synthetase (GS) and glutamate synthase (GOGAT). The GS enzyme is either located in the cytoplasm (GS 1 ) or in the chloroplast (GS 2 ). Glutamine synthetase 1 is regulated in different plants at the transcriptional level and there are some reports of regulation at the level of protein stability. Here we present data that clearly establish that GS 1 in plants is also regulated at the level of transcript turnover and at the translational level. Using a Glycine max (soybean) GS 1 transgene, with and without its 3¢ untranslated region (UTR), driven by the constitutive CaMV 35S promoter in Medicago sativa (alfalfa) and Nicotiana tabacum (tobacco), we show that the 3¢ UTR plays a major role in both transcript turnover and translation repression in both the leaves and the nodules. Our data suggest that the 3¢ UTR mediated turnover of the transcript is regulated by a nitrogen metabolite or carbon/nitrogen ratios. We also show that the 3¢ UTR of the gene for the soybean GS 1 confers post-transcriptional regulation on a reporter gene. Our dissection of post-transcriptional and translational levels of regulation of GS in plants shows that the situation in plants strongly resembles that in other organisms where GS is regulated at almost all levels. Multistep regulation of GS shows the high priority given by organisms to regulating and ensuring optimal control of nitrogen substrates and preventing overproduction of glutamine and drainage of the glutamate pool.

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Section: Resultsmentioning

confidence: 88%

“…For the analysis of the GS 1 alfalfa genes, 3′ UTR probes specific for the constitutive GS 1 gene ( MsGS100 ) and the nodule‐enhanced GS 1 gene ( MsGS13 ) were used. The expression of the chloroplastic GS 2 isoform was monitored by using a full‐length alfalfa cDNA clone for GS 2 (Zozaya‐Hinchliffe et al. , 2005).…”

Section: Methodsmentioning

confidence: 99%

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa

et al. 2006

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“…In addition to being a substrate for N assimilation, nitrate also acts as a signal triggering changes in gene expression that regulate a wide variety of processes, including N metabolism. For instance, nitrate induces the expression of NR , NIR , and GS2 in Arabidopsis thaliana (Sakakibara et al, 2006) and other plant species (Crawford, 1995; Zozaya‐Hinchliffe et al, 2005). Other than nitrate, cytokinin (CK), a plant hormone receiving increased attention for its stress‐responsive effects in agriculture and turfgrass industries (Schmidt et al, 2003), can also function as a signal to affect N metabolism, such as inducing NRA (Sakakibara et al, 2006).…”

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confidence: 99%

Circadian Patterns of the Major Nitrogen Metabolism–Related Enzymes and Metabolites in Creeping Bentgrass and the Influence of Cytokinin and Nitrate

et al. 2011

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Creeping bentgrass {Agrostis stolonifera L.) is a major low-cut turfgrass species worldwide. Information is limited on the diurnal variation in its N metabolism, particularly the impacts of cytokinin (CK) and nitrate (NO3"). To gain insight into the diurnal fluctuation of N metabolism and the effects of CK and nitrate, the transcript abundance of the major N metabolism enzymes in shoots, including nitrate reductase (NR), nitrite reductase, chloroplastic glutamine synthetase (GS2), ferredoxin-dependent glutamate synthase (Fd-GOGAT), and glutamate dehydrogenase, were studied during the day/ night cycle (14/10 h). All measured parameters exhibited clear diurnal changes with some differences among treatments (control, CK at 50 MM, and nitrate at 7.5 kg N ha-'), except GS2 expression and total protein. Both NR expression and nitrate content showed a peak at 0430 h (8.5 h in dark). Nitrate nutrition increased diurnal change of nitrate content, showing an over two-fold diurnal difference compared to 63 and 81% differences for the control and CK treatment, respectively. Simultaneously, CK shifted the diurnal in vivo NR activity pattern. In addition, creeping bentgrass appears to be able to maintain N assimilation at night comparable to that during the day, demonstrated by either similar or even higher levels of measured parameters between certain phases of light and dark periods. This study provides further information for understanding how CK and nitrate regulate N metabolism in creeping bentgrass.

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“…Thus, more carbon skeletons might be required for roots than for leaves to overcome the limitation of nitrogen assimilation capacity. In previous studies, the regulation of feeding of 2‐OG on GS isoform expression was reported in dark‐adapted Arabidopsis seedlings (Oliveira and Coruzzi 1999) as well as in nitrogen‐starved alfalfa roots (Zozaya‐Hinchliffe et al 2005). All the observations indicated a specific role of 2‐OG in plant tissues of carbon depletion or carbon insufficiency; however, the biochemical background in the regulation of 2‐OG was unclear.…”

Section: Discussionmentioning

confidence: 99%

Regulation of carbon and nitrogen metabolisms in rice roots by 2‐oxoglutarate at the level of hexokinase

Yuan

Wang

et al. 2007

Physiologia Plantarum

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Feeding experiments were designed, to investigate the role of 2‐oxoglutarate (2‐OG) in regulation of carbon and nitrogen metabolisms in non‐photosynthetic tissues of rice (Oryza sativa L.), and enzyme activities involved in the metabolisms as well as contents of several relating metabolites were determined in the roots. The enhancement of 2‐OG level by feeding 2‐OG or metabolizable sugars [sucrose (Suc) or glucose (Glc)], rather than by feeding non‐metabolizable carbon sources (mannose or mannitol), led to increase in enzyme activities, including hexokinase (HXK, EC 2.7.1.1), nicotinamide adenine dinucleotide phosphate (NADP)+‐dependent isocitrate dehydrogenase (NADP+‐ICDH, EC 1.1.1.42), phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), glutamine synthetase (GS, EC 6.3.1.2) and the reduced form of nicotinamide adenine dinucleotide (NADH)‐dependent glutamate synthase (NADH‐GOGAT, EC 1.4.1.14). In addition, the increase in ammonium uptake, glutamine and glutamate (Glu) as well as the decrease in soluble carbohydrates were observed. The effects of feeding 2‐OG or metabolizable sugars were reversed by feeding of N‐acetyl‐glucosamine (NAG; a HXK inhibitor). The decreased 2‐OG level by the feeding of NAG alone led to increase in soluble carbohydrates and decrease in the enzyme activities, ammonium uptake as well as Glu content. The effects of NAG were reversed by supply of 2‐OG, Suc and Glc. These results suggest that nitrogen uptake and assimilation as well as their related carbohydrate metabolism in rice roots were regulated in coordination by 2‐OG level, and HXK activity was involved in the regulation of 2‐OG.

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Nitrogen and metabolic regulation of the expression of plastidic glutamine synthetase in alfalfa (Medicago sativa)

Cited by 20 publications

References 61 publications

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa

Circadian Patterns of the Major Nitrogen Metabolism–Related Enzymes and Metabolites in Creeping Bentgrass and the Influence of Cytokinin and Nitrate

Regulation of carbon and nitrogen metabolisms in rice roots by 2‐oxoglutarate at the level of hexokinase

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Nitrogen and metabolic regulation of the expression of plastidic glutamine synthetase in alfalfa (Medicago sativa)

Cited by 20 publications

References 61 publications

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS1) affects transcript stability and protein accumulation in transgenic alfalfa

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS1) affects transcript stability and protein accumulation in transgenic alfalfa

Circadian Patterns of the Major Nitrogen Metabolism–Related Enzymes and Metabolites in Creeping Bentgrass and the Influence of Cytokinin and Nitrate

Regulation of carbon and nitrogen metabolisms in rice roots by 2‐oxoglutarate at the level of hexokinase

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Product

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The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa

The 3′ untranslated region of a soybean cytosolic glutamine synthetase (GS₁) affects transcript stability and protein accumulation in transgenic alfalfa