Rhythmic Nitrate Reductase Activity in Leaves of <i>Capsicum annuum</i> L. and the Influence of Kinetin

Steer, B. T.

doi:10.1104/pp.57.6.928

Cited by 32 publications

(12 citation statements)

References 24 publications

(32 reference statements)

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“…Observations on diurnal centrations when stipplied with noti-Smiting nitrate con-variation in NR activity are numerous for both in vitro centrations in the growth medium (Steingrover et al (e.g. Lillo 1983, Nicholas et al, 1976, Steer 1976) and in 1982). Light, temperature and nitrate supply to the vivo activity (Lillo and Henriksen 1984, Rajagopal et al roots can exert their influence via changes in nitrate up-1977, Stuith and.…”

Section: Introductionmentioning

confidence: 99%

Daily changes in uptake, reduction and storage of nitrate in spinach grown at low light intensity

Steingröver

Ratering

Siesling

1986

Physiologia Plantarum

108

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Under poor light conditions, as normally used during winter production of greenhouse vegetables, the nitrate concentration in the shoot of spinach (Spinacia oleracea L. cv. Vroeg Reuzenblad) showed a diurnal rhythm. This rhythm was mainly caused by a decrease during the day, followed by an increase during the night in the leaf blade nitrate concentration. Nitrate was mainly located in the vacuoles of the leaf blades. A strong correlation was found between net uptake of nitrate by the roots and the nitrate concentration in the leaf blade vacuoles. The nitrate concentration in the leaf blades increased during the initial hours of the night. This increase was caused by a marked increase in the net uptake rate of nitrate by the roots during the first hours of the dark period. During the second part of the night both net uptake rate of nitrate by the roots and the vacuolar nitrate concentration in the leaf blades remained constant. We conclude that nitrate is taken up for osmotic purposes when light conditions are poor because of a lack of organic solutes. During the night, nitrate influx into the vacuole is needed for replacement of organic solutes, which are metabolized during the night, and possibly also for leaf elongation growth. During the day, vacuolar nitrate may be exchanged for newly synthesized organic solutes and be metabolized in the cytoplasm. A strong diurnal rhythm in nitrate reductase (NR; EC 1.6.6.1.) activity was absent, due to the poor light conditions, and in vitro NR activity was not correlated with nitrate flux from the roots. In vivo NR activity also lacked a strong diurnal rhythm, but it was calculated that in situ nitrate reduction was much lower during the night, so that the major nitrate assimilation took place during the day.

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Section: Introductionmentioning

confidence: 99%

Daily changes in uptake, reduction and storage of nitrate in spinach grown at low light intensity

Steingröver

Ratering

Siesling

1986

Physiologia Plantarum

108

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“…Diurnal rhythms in NRA3 in leaves (1,15), as well as apparently endogenous rhythms in activity (16) are well known. A recent publication (14) has established that the removal of shoots from cotton roots led to a marked decline in NRA assayed (in vivo) and in sugar content in the roots, but it is not clear if any indirect light-mediated control of NRA is sustained at different times during the photoperiod.…”

mentioning

confidence: 99%

Effect of Shoot Removal and Malate on the Activity of Nitrate Reductase Assayed in Vivo in Barley Roots (Hordeum vulgare cv. Midas)

Deane‐Drummond¹,

Clarkson²,

Johnson

1979

Plant Physiol.

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There is a diurnal variation of nitrate reductase activity (NRA) In Vivo Assay. Tests in our laboratory showed that the following conditions were optimal. Incubation medium contained 50 mm phosphate buffer, 1% propanol (v/v), 100 mm nitrate at pH 8.0. Roots were transferred to glass bottles containing cold incubation medium (4 ml/100 mg root) and vacuum-infiltrated for 4 min. Incubation was for 20 min at 27 C in the dark and the reaction terminated by boiling for 10 min. Suitable blanks and zero time controls were run for each assay. After cooling, nitrite was measured in a 1-ml aliquot by adding I ml sulfanilic acid (1% in 3 N HCI) and then I ml N-l-naphthylethylene diamine dihydrochloride (0.05%). The optical density at 540 nm was measured at least 2 h later.In Vitro Assay. The extraction medium contained 3% casein, 10 mM cysteine, I mm EDTA in 50 mm phosphate buffer at pH 7.5. The ratio of tissue to extractant was 1:5 (w/v); the extract was made at 3 C using a pestle and mortar and then centrifuged for 10 min at 18,000g. Aliquots of the supernatant (0.1 ml) were mixed with a solution containing NADH (0.2 mg/ml), 10 mm KNO3 made up in 100 mm phosphate buffer at pH 7.8 giving a final volume of I ml. The mixture was incubated for 15 min at 27 C and was then treated with 0.5 ml of boiling 0.3 M zinc sulfate.After cooling, 0.2 ml of I N NaOH was added and the mixture centrifuged for 10 min. Nitrite in the supernatant was determined as in the in vivo assay. RESULTS AND DISCUSSIONThe results presented here have to be interpreted in the light of the limitations and advantages of the assay technique used (3). The in vivo assay, unlike the in vitro assay, does not have an exogenous supply of reducing power (3). Moreover casein and cysteine protectants added to the in vitro assay prevent inactivation of enzyme during the assay period, whereas in the in vivo assay the propan-l-ol treatment could release endogenous inhibitory substances.

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“…Statistically significant results were obtained that suggested that protein(s) with molecular weights of 26,000 daltons were preferentially synthesized in the photoperiod compared to the dark period. No evidence was found for the differential synthesis of proteins within the photoperiod.The reduction of nitrate exhibits a marked periodicity with three peaks of activity during the photoperiod, in leaves of Capsicum annuum (18,19). The consequent variability in the supply of reduced nitrogen is reflected in the amino acid pool size in the leaves (13,16) and there is an indication of an integrated control of carbon supply and reduced nitrogen supply for amino acid synthesis (17).…”

mentioning

confidence: 99%

“…The reduction of nitrate exhibits a marked periodicity with three peaks of activity during the photoperiod, in leaves of Capsicum annuum (18,19). The consequent variability in the supply of reduced nitrogen is reflected in the amino acid pool size in the leaves (13,16) and there is an indication of an integrated control of carbon supply and reduced nitrogen supply for amino acid synthesis (17).…”

mentioning

confidence: 99%

Within-day Changes in the Polyribosome Content and in Synthesis of Proteins in Leaves of Capsicum annuum L

Steer

Blackwood²

1978

Plant Physiol.

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Capsicum annuum cv. California Wonder was grown in controlled environment with a 12-hour photoperiod. The polyribosome content of leaves varied from 60 to 72% of total ribosomes with the highest level occurring in the middle of the photoperiod and the lowest in the middle of the dark period. The variation was accounted for by changes in the content of large polyribosomes (hexamers and larger). There was no indication of an immediate effect on polyribosome content of light-on or light-off.The synthesis of proteins at two times in the 24-hour cycle was compared using a dual isotope technique. Statistically significant results were obtained that suggested that protein(s) with molecular weights of 26,000 daltons were preferentially synthesized in the photoperiod compared to the dark period. No evidence was found for the differential synthesis of proteins within the photoperiod.The reduction of nitrate exhibits a marked periodicity with three peaks of activity during the photoperiod, in leaves of Capsicum annuum (18,19). The consequent variability in the supply of reduced nitrogen is reflected in the amino acid pool size in the leaves (13,16) and there is an indication of an integrated control of carbon supply and reduced nitrogen supply for amino acid synthesis (17).We report here information on the synthesis of proteins in Capsicum leaves in the 24-hr cycle. The capacity for protein synthesis has been assessed by measurement of the polyribosome content of ribosome preparations, and by using a dual label technique we have identified proteins that are synthesized preferentially at particular times in the 24-hr cycle. We were able to determine whether or not amino acids synthesized at different times in the photoperiod were used for the synthesis of different proteins in the leaf. To our knowledge, the only published information on the timing of protein synthesis in green tissue during the 24-hr cycle is from work on Lemna minor (4).Clark et al. (5) Expanding leaves were used as experimental material. They were selected using the same criteria as previously reported (16).Polysome Analysis. Each sample in experiment I consisted of leaves 4, 5, and 6 from four plants, and in experiment 2, of leaves 6, 7, and 8 from three plants. At the sampling times leaf laminae were excised, the midvein removed, and the sample rapidly weighed (about 4.5 and 7.7 g fresh weight for experiments 1 and 2, respectively). The samples were stored in liquid N2 for 2 to 23 hr.For polysome preparation the high ionic strength, and high pH systems of Davies et al. (7) and Jackson and Larkins (9) were used. The frozen samples were homogenized, using a Polytron at setting 8 for 5 sec, in a solution of 200 mm sucrose, 200 mm Tris-HCI (pH 9.0), 400 mm KCl, 35 mM MgCl2, 25 mm EGTA.2 For each g fresh weight of sample 3.6 ml of solution were used. The slurry was filtered through three layers of well washed muslin and Triton X-100 was added to the filtrate to a final concentration of 2%. The filtrate was centrifuged at 10,000g for 10 min. The su...

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Rhythmic Nitrate Reductase Activity in Leaves of Capsicum annuum L. and the Influence of Kinetin

Cited by 32 publications

References 24 publications

Daily changes in uptake, reduction and storage of nitrate in spinach grown at low light intensity

Daily changes in uptake, reduction and storage of nitrate in spinach grown at low light intensity

Effect of Shoot Removal and Malate on the Activity of Nitrate Reductase Assayed in Vivo in Barley Roots (Hordeum vulgare cv. Midas)

Within-day Changes in the Polyribosome Content and in Synthesis of Proteins in Leaves of Capsicum annuum L

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