Factors Influencing Nitrate Reduction in Soybean Foliage

Tingey, David T.; Fites, Roger C.; Baharsjah, Justika Sjarifuddin

doi:10.1111/j.1469-8137.1974.tb04602.x

Cited by 13 publications

(12 citation statements)

References 21 publications

(32 reference statements)

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“…This is in contrast to a previous report (10) in which a minimum glucose concentration of 48 mm was required to stimulate significant increases in in vivo NR activity from dark-pretreated soybeans. The addition of MgSO4 to the assay medium stimulated NR activity at all glucose concentrations, although the increases exceeded significant levels at only the 5 mm glucose level.…”

Section: Methodscontrasting

confidence: 99%

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Nitrate Reductase Activity in Soybeans (Glycine max [L.] Merr.)

Nicholas¹,

Harper²,

Hageman³

1976

Plant Physiol.

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Growth chamber studies with soybeans (Glycine max [L.] Mef.) were designed to determine the relative limitations of NO3-, NADH, and nitrate reductase (NR) per se on nitrate metabolism as affected by light and temperature. Three NR enzyme assays (+NO3-in vivo, -NO3-in vivo, and in vitro) were compared. NR activity decreased with al assays when plants were exposed to dark. Addition of NO3-to the in vivo NR assay medium increased activity (over that of the -NO3-in vivo assay) at aUl sampUng periods of a normal day-night sequence (14 hr-30 C day; 10 hr-20 C night), indicating that NO3-was rate-limiting. The stimulation of In vivo NR activity by NO3-was not seen in plants exposed to extended dark periods at elevated temperatures (16 hr-30 C), indicating that under those conditions, NO3-was not the limiting factor. Under the latter condition, in vitro NR activity was appreciable (19 ,umol NO2-[g fresh weight, hr]-1) suggesting that enzyme level per se was not the limiting factor and that reductant energy might be limiting.The addition of NADH to the in vivo NR assay medium did not stimulate NR activity, although it was not established that NADH entered the tissue. The addition of glucose, fructose 1,6-diphosphate, pyruvate, citrate, succinate, or malate to the in vivo assay medium significantly increased measurable NR activity of leaf tissue from plants pretreated to extended dark periods at elevated temperature. Glucose additions were most effective, usually stimulating increases 2-to 3-fold greater than the other metabolites. Increased NR activities from the various additives were attributed to production of NADH. The loss of in vivo NR activity in soybeans during darkness appeared to be due to the combination of a net loss of enzyme per se and energy depletion. The subsequent light stimulation of NR activity was likely due to increased availability of reductant energy as well as a net synthesis of the NR enzyme.Since the original characterization of reductant energy requirements of NR2 (3), many investigators have reported on the capacity of various plant species to utilize NADH as the preferred electron donor for NR (1, 2, 5). Klepper et al. (5) concluded that sugars which migrated from the chloroplasts were the primary source of energy, and that the oxidation of glyceraldehyde 3-P was the in situ source of NADH for nitrate reduction in corn. Malate has also been implicated as an energy source for NADH generation in corn (7). Tingey (10) reported that addition of 48 mm glucose to the incubation medium significantly I Cooperative investigation of the North Central Region, Agricultural

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Section: Methodscontrasting

confidence: 99%

“…Malate has also been implicated as an energy source for NADH generation in corn (7). Tingey (10) increased the in vivo NR activity of dark-pretreated soybeans. Partial purification of soybean NR has revealed two isozymes which have different preferential activities with NADH and NADPH (4).…”

mentioning

confidence: 96%

Nitrate Reductase Activity in Soybeans (Glycine max [L.] Merr.)

Nicholas¹,

Harper²,

Hageman³

1976

Plant Physiol.

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“…Beyond the optimum concentration, the exogenous nitrate inhibited the NRA. The reason for this inhibition is not known, but it has often been reported by others (3,6,8,11).…”

Section: Resultsmentioning

confidence: 81%

“…Within columns, values followed by different letters are significantly different nitrate has been explained by the fact that nitrate is an inducer and substrate for NR (12,13,14,15). However, the optimum concentrations of nitrate for in vivo NR assay have usually been much higher than the substrate requirements for the in vitro assay (11,16). This indicates that the entry of nitrate into the cytoplasm or the release of nitrite to the assay medium may be a factor limiting apparent NRA.…”

Section: Resultsmentioning

confidence: 89%

“…It has been found that the addition of nitrate to the assay medium stimulated NRA in many higher plants (8,11 Partitioning of the means is by LSD at the 5% level of significance. Within columns, values followed by different letters are significantly different nitrate has been explained by the fact that nitrate is an inducer and substrate for NR (12,13,14,15).…”

Section: Resultsmentioning

confidence: 99%

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Factors affecting thein vivonitrate reductase assay for mm 106 apple trees

Leè

Titus

1992

Communications in Soil Science and Plant Analysis

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Factors affecting the in vivo nitrate reductase (NR) assay were investigated in order to optimize the assay conditions for various tissues of MM 106 apple trees. The addition of nitrate and phosphate to the assay medium significantly increased nitrate reductase activity (NRA), but high concentrations of nitrate and phosphate inhibited the NRA. The optimum concentrations of nitrate and phosphate for in vivo NRA ranged from SO to 100 mM and were tissue-specific. The optimum pH of the assay medium was 7.5. The addition of 2% (v/v) npropanol to the assay medium stimulated NRA, but concentrations of n-propanol greater than 2% significantly decreased the NRA. Vacuum infiltration was effective in stimulating NRA. The in vivo NR assays for leaves and stems were linear for at least 60 minutes following an initial 30 minute lag, whereas there was no lag phase in root tissues. INTRODUCTIONMany attempts have been made to measure the NRA in woody plants, but little information is available for apple trees and the reported amounts of NRA in apple trees have been quite variable because many different methods have been used. Moreover, most reported NRA in apple trees were based on the in vitro NR assay in which phenolic compounds or other inhibitors often inactivated NR enzyme during extraction (1,2). Although the importance of the in vivo NR assay has been

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Effects of age and variety on nitrate reductase and nitrogen fractions in potato plants

Kapoor

1982

J Sci Food Agric

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The: effects of plant age and variety on the level of nitrate reductase activity in three varieties of Solanum tuberosum (Kennebec, Norchip and Early Ohio) have been studied by assaying nitrate reductase at different intervals during growth and development. Nitrate reductase appears to be localised in leaves and young stems. Negligible nitrate reductase activity was recorded in roots and tubers. The vaiieties differed significantly in nitrate reductase activity and the tuber protein nitrogen content paralleled the level of activity in leaves. The levels of nitrate reductase activities in leaves were also highly positively correlated with quantities of leaf inorganic nitrogen, protein and free amino acids. The activity began to decline at about 50 days after emergence, and this may be a useful indicator of when to apply nitrogen fertiliser so as to increase tuber protein content.

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Factors Influencing Nitrate Reduction in Soybean Foliage

Cited by 13 publications

References 21 publications

Nitrate Reductase Activity in Soybeans (Glycine max [L.] Merr.)

Nitrate Reductase Activity in Soybeans (Glycine max [L.] Merr.)

Factors affecting thein vivonitrate reductase assay for mm 106 apple trees

Effects of age and variety on nitrate reductase and nitrogen fractions in potato plants

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