Effect of phytohormones and tungsten on light-induced and nitrate-induced nitrate reductase activity of mustard cotyledons

Saroop, Sant; Chanda, Sumitra; Singh, Y. D.

doi:10.1007/s11738-000-0090-6

Cited by 5 publications

(3 citation statements)

References 26 publications

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“…However, Leleu and Vuylsteker (2004) reported that NRA in Brassica napus seedlings was independent of nitrate content and that both NRA and NR mRNA accumulation was much larger with sole NH 4 + provision than those with NO 3 -provision only. Saroop et al (2000) also showed that the nitrate is not required when NR was induced by light treatment in mustard (Brassica Juncea). Moreover, ammonium induced NRA in maize leaves only under light-incubated conditions (Mehta and Srivastava 1980).…”

Section: Discussionmentioning

confidence: 97%

Physiological and Molecular Responses of Nitrogen-starved Rice Plants to Re-supply of Different Nitrogen Sources

et al. 2006

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Rice grown under anaerobic waterlogged soil condition takes up ammonium as a major source of nitrogen (N). A substantial quantity of nitrate is taken up by rice when aeration conditions prevail. This work compared the physiological and molecular responses of N-depleted rice (Oryza sativa L. japonica ssp. cv. Wuyunjing) to re-supply of different N sources in a hydroponic system. Expression of six genes known to be related to N uptake and assimilation in roots was analyzed by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). N starvation increased root growth but decreased shoot biomass and nitrate reductase (NR) activity. In comparison to nitrate as N source, ammonium tended to inhibit root growth but significantly improved shoot growth, total N uptake, and, particularly, the translocation of N to the above ground parts. Replacing half of the ammonium by nitrate in the single ammonium solution increased glutamine synthetase (GS) activity and total N uptake. This replacement enhanced expression of OsAMT1;3 but decreased the expression of OsAMT1;2 in the roots. Likewise, replacing half of the nitrate by ammonium in the single nitrate solution, increased NR activity and expression of an NR gene (OsNR1) but suppressed expression of OsNRT2 in the roots. Expression of both OsAMT1;1 and a GS gene (OsGS1;1) was relatively constant and not affected by the N form or starvation in the rice roots. Predominant beneficial effects of dual supply of the two forms of N in comparison with a single form of N either as ammonium or as nitrate might be due to improvement of ammonium uptake due to nitrate presence near the roots and enhanced reduction of nitrate in leaves by ammonium.

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Section: Discussionmentioning

confidence: 97%

Physiological and Molecular Responses of Nitrogen-starved Rice Plants to Re-supply of Different Nitrogen Sources

et al. 2006

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“…35,36 Indeed, some authors reported a light-induced NR independent of NO 3 − in some species. 37,38 Its regulation seems to be different to the NO 3 − -induced NR 39 and its function remains to be elucidated. In this context, it is possible that the enhanced NR activity in presence of urea observed in our experiment could be due to an induction of a NO 3 − -independent NR.…”

Section: Discussionmentioning

confidence: 98%

Nitrate modifies the assimilation pattern of ammonium and urea in wheat seedlings

Garnica¹,

Houdusse²,

Zamarreño³

et al. 2009

J Sci Food Agric

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These results suggest that the effect of nitrate is compatible with a rapid and transient increase in the activity of glutamine synthetase and urease during the first hour after the onset of treatments. Nevertheless, a possible effect of nitrate reducing ammonium accumulation through the activation of alternative metabolic pathways different from that involving glutamine synthetase cannot be ruled out. Finally, nitrate effects on amino acid concentration indicate that, whereas ammonium assimilation takes place principally in the root, urea and nitrate assimilation occurred in the shoot, under the conditions of the experiment.

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“…Nevertheless, a significant decrease in nitrogenase activity of several free living N 2 fixing bacteria in the presence of W was reported. ,, Although the exact toxicity mechanism is not known, it was suggested that a replacement of Mo by W renders the N 2 -fixing nitrogenase enzyme inactive . Also, the activity of nitrate reductase, a molybdoenzyme responsible for the assimilatory reduction of nitrate to nitrite, was repeatedly shown to be inhibited in the presence of monomeric tungstate with its negative effect again being attributed to the prevention of the formation of an active Mo cofactor required for NR catalytic activity. − Deng et al found that W inactivated NR but simultaneously increased NR protein abundance and corresponding mRNA tissue concentrations, leading to an over-expression of the NR genes. In our study, W had contrasting effects on the interrelated activities of the studied molybdoenzymes (i.e., nitrate reductase, and nitrogenase, respectively) in nodulated soybeans, indicating complex interactions between (pH-dependent) W solubility and speciation, pH and texture-driven organic N mineralization and stabilization, and molybdoenzyme-driven plant N nutrition.…”

Section: Discussionmentioning

confidence: 99%

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans

Oburger

Cid

Preiner

et al. 2018

Environ. Sci. Technol.

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Increasing use of tungsten (W)-based products opened new pathways for W into environmental systems. Due to its chemical alikeness with molybdenum (Mo), W is expected to behave similarly to its “twin element”, Mo; however, our knowledge of the behavior of W in the plant–soil environment remains inadequate. The aim of this study was to investigate plant growth as well as W and nutrient uptake depending on soil chemical properties such as soil pH and texture. Soybean (Glycine max cv. Primus) was grown on two acidic soils differing in soil texture that were either kept at their natural soil pH (pH of 4.5–5) or limed (pH of ≥7) and amended with increasing concentrations of metallic W (control and 500 and 5000 mg kg–1). In addition, the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N2 fixation (nitrogenase) was also investigated. Our results showed that the risk of W entering the food web was significantly greater in high-pH soils due to increased solubility of mainly monomeric W. The effect of soil texture on W solubility and phytoavailability was less pronounced compared to soil pH. Particularly at intermediate W additions (W 500 mg kg–1), symbiotic nitrogen fixation was able to compensate for reduced leaf nitrate reductase activity. When W soil solution concentrations became too toxic (W 5000 mg kg–1), nodulation was more strongly inhibited than nitrogenase activity in the few nodules formed, suggesting a more-efficient detoxification and compartmentalization mechanism in nodules than in soybean leaves. The increasing presence of polymeric W species observed in low-pH soils spiked with high W concentrations resulted in decreased W uptake. Simultaneously, polymeric W species had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our study demonstrates the importance of accounting for soil pH in risk assessment studies of W in the plant–soil environment, something that has been completely neglected in the past.

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Effect of phytohormones and tungsten on light-induced and nitrate-induced nitrate reductase activity of mustard cotyledons

Cited by 5 publications

References 26 publications

Physiological and Molecular Responses of Nitrogen-starved Rice Plants to Re-supply of Different Nitrogen Sources

Physiological and Molecular Responses of Nitrogen-starved Rice Plants to Re-supply of Different Nitrogen Sources

Nitrate modifies the assimilation pattern of ammonium and urea in wheat seedlings

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans

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