Oscillations in the Activities of Enzymes of Nitrate Reduction and Ammonia Assimilation in <i>Glycine max</i> and <i>Zea mays</i>

Duke, Stanley H.; Friedrich, J. W.; Schrader, L. E.; Koukkari, Willard L.

doi:10.1111/j.1399-3054.1978.tb04081.x

Cited by 49 publications

(10 citation statements)

References 39 publications

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“…5) which decreased with increasing light intensity. GDH activity is reportedly enhanced by darkness (Duke et al, 1978) among other things, with phytochrome being the controlling factor (Duke, Koukkari and Soulen, 1975). Roots of Syzygium exhibited low GDH activity which was not light affected (Fig.…”

Section: Discussionmentioning

confidence: 92%

“…Glutamine synthetase activity was determined by estimating y-glutamylhydroxamate production by a modification of the method of Duke et al (1978). Incubation mixtures and the order of addition of components were as follows: 60 /tmol Tris^HCl (pH 7 5), 240 //mol glutamate (pH 7-0), 240 //mol hydroxylamine (pH 6 8), 100/tmol MgSO4, 50/(mol of ATP and 10 ml of crude enzyme solution in a final volume of 3 4 ml.…”

Section: Determination Of Enzyme Activitiesmentioning

confidence: 99%

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Physiological Aspects of Rainforest Regeneration

Chandler¹

1981

New Phytologist

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SUMMARYSyzygium fioribundum, a rainforest climax species and Solatium mauritianmn, a rainforest pioneer, were raised in sand cultures containing NO3" or NH4+ under various shade regimes. Optimum growth of Syzygium occurred with NHj"*" and of Solamim with NO^". Ammonium appeared toxic for Solatium at low light intensity.Shoot-root ratios of Syzygiutn were remarkably constant irrespective of light intensity but ammonium promoted greater leaf production. Conversely, Solatium shoot-root ratios were not affected by nutrients but increased dramatically at low light intensity.Leaves of Syzygium exhibited high levels of glutamate dehydrogenase (GDH) activity which decreased with increasing light intensity. Roots oi Syzygiutn exhibited low GDH activity. This, together with high glutamine synthetase (GS) activity in the roots, suggests that GS is the main ammonium assimilating enzyme in the roots of Syzygiutti. GDH and GS are both active in the leaves of this species. High GDH and low GS activity in both leaves and roots of Solanutn suggests that GDH is the main NHj^ assimilating enzyme in this species.

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Section: Discussionmentioning

confidence: 92%

Section: Determination Of Enzyme Activitiesmentioning

confidence: 99%

Physiological Aspects of Rainforest Regeneration

Chandler¹

1981

New Phytologist

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“…GDH is known to be induced by NH4' (1 1). Differences in NR activity with the various treatments reflect the small amounts of N03-added to plants at 13 C in the N03-strongly induces NR activity (10).…”

Section: Methodsmentioning

confidence: 99%

“…At (27) and those for other enzymes with a Tricine-Hepes buffer as before (14). Assays for the following enzymes were as previously described: NR (27), GDH and MDH (12), GS (10), GOGAT (11), GOT (14), PEPC (4), and GAO (28 min by the addition of 0.6 N acetic acid. Vial contents were then evaporated to dryness at 60 C, redissolved in a cocktail (14), and dpm determined by scintillation spectroscopy.…”

Section: Methodsmentioning

confidence: 99%

Low Root Temperature Effects on Soybean Nitrogen Metabolism and Photosynthesis

Duke¹,

Schrader²,

Henson³

et al. 1979

Plant Physiol.

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The influences of low root temperature on soybeans (Glycine max IL.1Merr. cv. Wells) were studied by germinating and maintaining plants at root temperatures of 13 and 20 C through maturity. At 42 days from the beginning of imbibition, 13 and 20 C plants were switched to 20 and 13 C, respectively. Plants were harvested after 63 days. Control plants (13 C) did not nodulate, whereas those switched to 20 C did and at harvest had C2H2 reduction rates of 0.2 micromoles per minute per plant. Rates of C2H2 reduction decreased rapidly in plants switched from 20 to 13 C; however, after 2 days, rates recovered to original levels (0.8 micromoles per minute per plant) and then began a slow decline until harvest. Arrhenius plots of C2H2 reduction by whole plants indicated a large increase in the energy of activation below the inflection at 15 C. Highest C2H2 reduction rates (1.6 micromoles per minute per plant) were at 58 days for the 20 C control. Root respiration rates followed much the same pattern as C2H2 reduction in the 20 C control and transferred plants. At harvest, roots from 13 C-treated plants had the highest activities for malate dehydrogenase, glutamate oxaloacetate transaminase, and phosphoenolpyruvate carboxylase. Roots from transferred plants had intermediate activities and those from the 20 C treatment the lowest activities. Newly formed nodules from plants switched from 13 to 20 C had much higher glutamate dehydrogenase than glutamine synthetase activity.Photosynthetic rates on a leaf area basis were about three times as high in the 20 C control as compared to 13 C control plants. Photosynthetic rates of plants switched from 20 to 13 C decreased to less than half the original rate within 2 days. Photosynthetic rates of plants switched from 13 to 20 C recovered to rates near those of the 20 C control plants within 2 weeks. All leaf enzymes assayed at harvest, with the exception of nitrate reductase, were highest in activity in the 20 C control plants.There have been few investigations on low temperature effects on roots. However, in legumes, low soil or root temperature decreases both nodulation and rates of N2 fixation (7,17,19,26,32). Many adverse effects of low soil temperature on chillingsensitive plants can be attributed to low-temperature-induced membrane phase transitions which slow protoplasmic streaming, increase permeability, and decrease the activities of membranebound enzymes by increasing Eas3 (13,14,25).

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“…The mode of action of glufosinate involves the inhibition of the glutamine synthetase (GS) enzyme, whose activity oscillates in relation to the circadian clock (Duke et al, 1978). The glyphosate herbicide, in turn, inhibits reactions from the shikimic acid pathway, which is important for the growth and development of plants.…”

Section: Circadian Clock and The Efficiency Of Herbicidesmentioning

confidence: 99%

Physiological and Genetic Bases of the Circadian Clock in Plants and Their Relationship with Herbicides Efficacy

Dalazen

Merotto

2016

Planta daninha

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-In order to adapt to daily environmental changes, especially in relation to light availability, many organisms, such as plants, developed a vital mechanism that controls time-dependent biological events: the circadian clock. The circadian clock is responsible for predicting the changes that occur in the period of approximately 24 hours, preparing the plants for the following phases of the cycle. Some of these adaptations can influence the response of weeds to the herbicide application. Thus, the objectives of this review are to describe the physiological and genetic mechanisms of the circadian clock in plants, as well as to demonstrate the relationship of this phenomenon with the effectiveness of herbicides for weed control. Relationships are described between the circadian clock and the time of application of herbicides, leaf angle and herbicide interception, as well as photosynthetic activity in response to the circadian clock and herbicide efficiency. Further, it is discussed the role of phytochrome B (phyB) in the sensitivity of plants to glyphosate herbicide. The greater understanding of the circadian clock in plants is essential to achieve greater efficiency of herbicides and hence greater control of weeds and higher crop yields.Keywords: time of herbicide application, weeds, photoreceptors, phytochromes. RESUMO -Para se adaptarem às variações ambientais diárias

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Oscillations in the Activities of Enzymes of Nitrate Reduction and Ammonia Assimilation in Glycine max and Zea mays

Cited by 49 publications

References 39 publications

Physiological Aspects of Rainforest Regeneration

Physiological Aspects of Rainforest Regeneration

Low Root Temperature Effects on Soybean Nitrogen Metabolism and Photosynthesis

Physiological and Genetic Bases of the Circadian Clock in Plants and Their Relationship with Herbicides Efficacy

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