Effect of light‐dark transition on glutamine synthetase activity in tomato leaves

Cánovas, Francisco M.; Ávila, Concepción; Botella, José Ramón; Valpuesta, Victoriano; Castro, Ignacio Núñez de

doi:10.1111/j.1399-3054.1986.tb05593.x

Cited by 17 publications

(6 citation statements)

References 28 publications

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“…GS is a chloroplastic enzyme, this was confirmed by immunocytolocalization (our unpublished data). GS activity may be modulated by the changes in those parameters in the chloroplast that occur during transition from dark to light (4). The present results emphasize the link between Fd-GOGAT and GS in the processes of nitrogen assimilation and reassimilation, which take place in the light periods.…”

Section: Immunocytolocalization Of Ferredoxin Glutamate Synthasementioning

confidence: 60%

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Botella

Verbelen²,

Valpuesta³

1988

Plant Physiol.

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Ferredoxin-glutamate synthase was localized in leaves and cotyledons of tomato (Lycopersicon escukntum, cv Helifrucht frushstamm) seedlings by immunocytochemical methods. The present work established that the enzyme was not only a constituent of chloroplast stroma of the mesophyll cells, but also of the cells of xylem parenchyma and epidermis.The catalytic steps involved in ammonia assimilation by the green tissues of higher plants are carried out by the GS2 (EC 6.3.1.2) and glutamate synthase enzymes (14). The later catalyzes the reductive transfer of amide nitrogen from glutamine to 2-oxoglutarate, and thus requires the presence of a two electron supplier. Two glutamate synthases have been reported in higher plants; each has a specific electron donor; one uses NAD(P)H (EC 1.4.1.14) and the other reduced ferredoxin (EC 1.4.7.1).Why both forms exist in the same tissue has yet to be explained, although some authors argue that the Fd-dependent enzyme plays a principal role in ammonia assimilation occurring in the light periods. In C3 plants, photorespiration takes place during these periods and the ammonia released must be reassimilated as part of a photorespiratory nitrogen cycle (9). Recent results on barley mutants confirm that Fd-GOGAT is specifically required for ammonia reassimilation (17). On the other hand, the NAD(P)Hdependent enzyme has been found to predominate in immature leaves (13). This accounts for the light-independent conversion of glutamine to glutamate.In the green leaves of tomato plants, one glutamine synthetase (5) and two glutamate synthases (1) have been described. To determine their physiological roles, knowledge of the intracellular localization of these proteins is essential. The present work reports for the first time experiments to determine the intracellular localization of Fd-GOGAT using specific antibodies raised against the enzyme, purified as described elsewhere (1). Antibody Preparation. Monospecific antibodies against tomato leaf Fd-GOGAT were raised by inoculating rabbits with homogeneous enzyme. Four intradermal injections of the purified enzyme (100 ,g) were given at 14 d intervals, the first injection with the complete Freund adjuvant, and the three others with the incomplete adjuvant. Ten d after the last injection, the rabbits were bled by the ears, the serum was separated and stored at -24°C until use.Immunodiffusion. The double immunodiffusioh was carried out using the procedure described by Ouchterlony and Nilsson (15). Ten ul of antiserum against Fd-GOGAT and 12 ,l of crude extract from green tomato leaves were placed in separated wells of 1% (w/v) agar plates and incubated for 48 h at 4°C. Following this they were rinsed for 2 h with PBS and then with water for another 2 h. The protein precipitate was stained with Coomassie brilliant blue.Immunoelectrophoresis. Aliquots of crude extract (10 ,ul) were run in 1% agarose plates, using 0.2 M Tris-glycine buffer (pH 8.0) and 7.5 V cm of power supply; after the electrophoretic run, the antiserum (180 ,ul) was added...

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Section: Immunocytolocalization Of Ferredoxin Glutamate Synthasementioning

confidence: 60%

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Botella

Verbelen²,

Valpuesta³

1988

Plant Physiol.

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“…1) demonstrate that the increase in GS activity is not a special ammonium effeet but a nitrogen effect in general. In the case of the light-treated seedlings (WL and HL) this effect may be correlated to the efficiency of photosynthesis, since in green leaves nitrogen reduction and the subsequent assimilation of ammonium into glutamate are photosynthetic reactions (Canovas et al 1986, Kang and Hymowitz 1988, Wallsgrove et al 1983). Accordingly, GS activity in mustard cotyledons is highly dependent on the energy flux (Tab.…”

Section: Discussionmentioning

confidence: 99%

Different effects of supplied ammonium on glutamine synthetase activity in mustard (Sinapis alba) and pine (Pinus sylvestris) seedlings

Vollbrecht

Klein

Kasemir

1989

Physiologia Plantarum

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H. 1989. Different effects of supplied ammonium on glutamine synthetase aetivity in mustard (Sitiapis alba) and pine {Pinus sytvestris) seedlings. -Physiol. Plant. 77: 129-135.The activity of glutamine synthetase (GS) in mustard (Sinapis alba L.) and Scots pine (Pintis sylvestris L.) seedlings was used as an index to evaluate the capacity to cope with excessive ammonium supply. In these 2 speeies GS aetivity was differently affected by the application of nitrogen compounds (NH| or NOj). Mustard seedlings older than 5 days showed a considerable increase in GS activity after NH.^ or NOj applieation. This response was independent of the energy flux, but GS activity in general was positively affeeted by light. Endogenous NHj did not accumulate greatly after nitrogen supply. In contrast, seedlings of Scots pine accumulated NH| in cotyledons and roots and showed no stimulation of GS activity after the application of ammonium. In addition, root growth was drastically reduced. Thus, the pine seedlings seem to have insufficient capacity to assimilate exogenously supplied atnmotiiutn. NO,^, however, did not lead to any harmful effects.

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“…These data suggest that herbicide uptake, translocation, or other physiological processes, in addition to leaf angle, contribute to reduced glufosinate efficacy when applications are made near sundown. Because glufosinate inhibits GS, it is possible that the inactivity of this enzyme in darkness (Cánovas et al 1986) may result in less absorption of glufosinate or dilution on account of increased translocation. This is currently under investigation.…”

Section: Timementioning

confidence: 99%

Diurnal Fluctuations and Leaf Angle Reduce Glufosinate Efficacy¹

Sellers¹,

Smeda²,

Johnson³

2003

Weed Technology

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Velvetleaf plants have diurnal leaf movements, which may result in decreased interception of herbicides when applications are made near sunset. However, it is not known if leaf angle alone accounts for diurnal fluctuations in efficacy. Greenhouse experiments were conducted to determine the effect of time of day (TOD) of application and velvetleaf leaf angle on glufosinate efficacy and spray interception. Glufosinate at 90, 180, and 360 g ai/ha was applied to 10-cm-tall plants at 4:00, 6:00, 7:00, 7:30, and 8:00 P.M., respectively. Leaf angles were either manipulated physically to −90° or the plant's natural 2:00 P.M. leaf angle (approximately −10°) or were allowed to exhibit their natural leaf movements. Plant dry weight 3 wk after treatment revealed that TOD effects were observed for all leaf angle treatments after glufosinate application at 90 g/ha. At 180 g/ha glufosinate, there was no TOD effect for plants with 2 P.M. leaf angles, whereas there was a TOD effect for plants with −90° and natural leaf angles. At 360 g/ha glufosinate, biomass for the −90° leaf angle plants was similar to that for the natural and the 2:00 P.M. leaf angle plants when glufosinate was applied at 4:00 P.M. but was significantly different at or after 6:00 P.M. This suggests that at least 4 h of light is needed to provide optimum herbicide activity when spray interception is reduced as a result of leaf movements. Leaf angle decreased by as much as 70% from 4:00 to 8:00 P.M., which resulted in approximately 50% less spray interception at 8:00 P.M. than at 4:00 P.M. These data provide evidence that leaf angle plays a pivotal role in reducing glufosinate efficacy when applications are made near sundown. However, leaf angle is not the sole reason for reduced efficacy because TOD effects were observed at different leaf angles with 4 h of light, after an application of 360 g/ha glufosinate.

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Effect of light‐dark transition on glutamine synthetase activity in tomato leaves

Cited by 17 publications

References 28 publications

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Different effects of supplied ammonium on glutamine synthetase activity in mustard (Sinapis alba) and pine (Pinus sylvestris) seedlings

Diurnal Fluctuations and Leaf Angle Reduce Glufosinate Efficacy¹

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Effect of light‐dark transition on glutamine synthetase activity in tomato leaves

Cited by 17 publications

References 28 publications

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Immunocytolocalization of Ferredoxin-GOGAT in the Cells of Green Leaves and Cotyledons of Lycopersicon esculentum

Different effects of supplied ammonium on glutamine synthetase activity in mustard (Sinapis alba) and pine (Pinus sylvestris) seedlings

Diurnal Fluctuations and Leaf Angle Reduce Glufosinate Efficacy1

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Diurnal Fluctuations and Leaf Angle Reduce Glufosinate Efficacy¹