Nitrate reductase and glutamine synthetase activity in leaves and roots of nitrate-fedHelianthus annuus L.

Kaiser, Jozef; Lewis, O. A. M.

doi:10.1007/bf02182818

Cited by 98 publications

(61 citation statements)

References 11 publications

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“…Extracts were centrifuged at 20,000g for 20 min at 4°C. NR activity was measured according to Kaiser and Lewis (1984) with some modifications. The reaction was initiated by the addition of 700 mL of reaction buffer (50 mM KH 2 PO 4 -KOH buffer, pH 7.5, 10 mM KNO 3 , and 0.1 mM NADH) to 100 mL of total soluble proteins.…”

Section: Enzyme Assaysmentioning

confidence: 99%

Stress-Induced Cytokinin Synthesis Increases Drought Tolerance through the Coordinated Regulation of Carbon and Nitrogen Assimilation in Rice

et al. 2013

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The effects of water deficit on carbon and nitrogen metabolism were investigated in flag leaves of wild-type and transgenic rice (Oryza sativa japonica 'Kitaake') plants expressing ISOPENTENYLTRANSFERASE (IPT; encoding the enzyme that mediates the rate-limiting step in cytokinin synthesis) under the control of P SARK , a maturation-and stress-induced promoter. While the wildtype plants displayed inhibition of photosynthesis and nitrogen assimilation during water stress, neither carbon nor nitrogen assimilation was affected by stress in the transgenic P SARK ::IPT plants. In the transgenic plants, photosynthesis was maintained at control levels during stress and the flag leaf showed increased sucrose (Suc) phosphate synthase activity and reduced Suc synthase and invertase activities, leading to increased Suc contents. The sustained carbon assimilation in the transgenic P SARK ::IPT plants was well correlated with enhanced nitrate content, higher nitrate reductase activity, and sustained ammonium contents, indicating that the stress-induced cytokinin synthesis in the transgenic plants played a role in maintaining nitrate acquisition. Protein contents decreased and free amino acids increased in wild-type plants during stress, while protein content was preserved in the transgenic plants. Our results indicate that the stress-induced cytokinin synthesis in the transgenic plants promoted sink strengthening through a cytokinin-dependent coordinated regulation of carbon and nitrogen metabolism that facilitates an enhanced tolerance of the transgenic plants to water deficit.

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Section: Enzyme Assaysmentioning

confidence: 99%

Stress-Induced Cytokinin Synthesis Increases Drought Tolerance through the Coordinated Regulation of Carbon and Nitrogen Assimilation in Rice

et al. 2013

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“…GS activity was determined by estimating the formation of glutamylhydroxamate at 540 nm after complexing with acidified ferric chloride (Kaiser and Lewis 1984). The reaction mixture contained 100 mM Tris-HCl buffer (pH 7.4) (consisting of 80 mM hydroxylamine, 20 mM glutamate, 80 mM MgSO 4 , and 2 mM EDTA-2Na), 10 mM ATP and enzyme extract.…”

Section: Enzyme Extractions and Assaysmentioning

confidence: 99%

Photosynthetic carbon and nitrogen metabolism and the relationship between their metabolites and lipid peroxidation in dwarf bamboo (Fargesia rufa Yi) during drought and subsequent recovery

Liu

Wang

Pan

et al. 2015

Trees

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Key message Differential regulations of C and N metabolism in dwarf bamboo improve the capacity of osmotic adjustment, and also their metabolites may play an important role for protection against membrane lipid peroxidation under drought, thus accelerating recovery after rewatering. Abstract Dwarf bamboo (Fargesia rufa Yi), is a staple food for the endangered giant panda, but little is known about the impact of drought on bamboo species and its recovery mechanism. This study investigated the response of carbon (C) and nitrogen (N) metabolism to drought and subsequent recovery, and the relationship of their metabolites with lipid peroxidation. Photochemistry was reversibly down-regulated after drought, but a longer recovery time is needed. The accelerated degradation of starch due to a rapid increase in amylase activity resulted in higher soluble sugar only in severe drought-stressed plants after 30 days of drought. Sucrose content was not affected by drought because of the relative increases in activities of invertase, sucrose synthase, and sucrose phosphate synthase. As nitrate concentration increased in parallel with nitrate reductase activity, ammonium (NH 4 ? ) production was enhanced by drought. Also, activated glutamine synthetase/glutamate synthase cycle stimulated NH 4? assimilation, while hydrolysis of soluble proteins was accelerated, resulting in accumulation of amino acids. After rewatering, re-balancing of C metabolism has gradually begun, but a stronger N metabolism was still observed. The notable positive correlations between MDA and the contents of starch and proline after 15 days of drought as well as between MDA and the contents of soluble sugar, NSC and proline after 30 days of drought were displayed. We conclude that dwarf bamboo may not only differently regulate its C and N metabolism to improve the capacity of osmotic adjustment but also employ its different metabolites protect against membrane Communicated by M. Adams.

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“…Homogenates were filtered through miracloth and centrifuged at 30000 g for 20 mm at 4 °C and the supernatant was decanted and kept on ice. In vitro assay of NR was as described by Kaiser & Lewis (1984) and Becana, Aparicio-Tejo & Sanchez-Diaz, (1985), as modified by Caba et al (1990). In vitro GS activity was determined using the methods described by Lillo (1984) and Canovas, Valpuesta & Nuiiez de Castro (1984), except that the buffer for the reaction was imidazol-HCl 0-15 mM (pH 7-8) containing 4 mM EDTA-Na.j.…”

Section: Measurementsmentioning

confidence: 99%

Effects of nitrogen source on growth, nutrition, photosynthetic rate and nitrogen metabolism of mycorrhizal and phosphorus‐fertilized plants of Lactuca sativa L.

1992

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SUMMARYPlants of Lactuca sativa L. cv. Romana were inoculated with two vesicular-arbuscular (VA) mycorrhizal fungi, Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe and Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. & Trappe, or provided with phosphorus. These three treatments plus a control were supplemented with 30 mM nitrogen as nitrate or ammonmm m 1 of 5 NO37NH/ ratios. Leaf and root weights, N, P, K, Ca and Mg absorption, as well as the percentage of root length colonized, were evaluated. Physiological parameters such as leaf area photosynthetic rate, glutam.ne synthetase (EC 6.3.1.2) and nitrate reductase (ECl.6.6.1) activity and leaf prolme accumulation were also determined. Mycorrhizal lettuce and P-fert.hzed plants derived significantly more benefit from N fertilization regardless of the N-source than did controls. Ammonium was a better N-source for non-mycorrhizal plants and nitrate for mycorrh.zal plants. P-fertilized lettuce reached maximum growth when N was supplied as 50% NO37 50 °o NH/ so that mycorrhizal status particularly affected the plant response to the form of N provided. Growth of mycorrhizal plants was comparable to non-mycorrh.zal P-fertihzed plants when N was provided as 100 % NH,^ or 25 % NO37 75 % NH,^ When N applications were as 50 % NO3 / 50 /o NH or 75 °/ NO 7 25 % NH + growth of P-fertilized plants was greater than mycorrhizal ones. Lettuce colonized by G mosseae grew fastest when fed nitrate only. Separation of NO,,-and NH,-assimilation into shoot and root compartments may account for the differential efFects of such ions into symbiotic and non-symbiot.c plants. Uptake or metabolism of nitrogenous forms was particularly affected in G. mo.s.ae-colonized plants, independent of P nutrition. P fertilization increased activities of nitrate reductase (NR) by 29 % and glutamine synthetase (GS) bv 24% compared with activities m control plants. In the case of G. fasctculatum-co\omzed plants, NR and GS w^re increased 5A\ and 117%, respectively, over control activities. In general, concentration of minerals, except Ca were increased m mvcorrhizal and P-fert.lized plants compared with controls. Assimilation of CO, and accumulation of proline were increased m G. fasciculatum-co\on,zed lettuce under all N regimes.

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Nitrate reductase and glutamine synthetase activity in leaves and roots of nitrate-fedHelianthus annuus L.

Cited by 98 publications

References 11 publications

Stress-Induced Cytokinin Synthesis Increases Drought Tolerance through the Coordinated Regulation of Carbon and Nitrogen Assimilation in Rice

Stress-Induced Cytokinin Synthesis Increases Drought Tolerance through the Coordinated Regulation of Carbon and Nitrogen Assimilation in Rice

Photosynthetic carbon and nitrogen metabolism and the relationship between their metabolites and lipid peroxidation in dwarf bamboo (Fargesia rufa Yi) during drought and subsequent recovery

Effects of nitrogen source on growth, nutrition, photosynthetic rate and nitrogen metabolism of mycorrhizal and phosphorus‐fertilized plants of Lactuca sativa L.

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