Glumatic‐Oxaloacetic Transaminase in Leaves of Phosphorus‐Deficient Citrus Plants

Achituv, Miriam; Bar‐Akiva, A.

doi:10.1111/j.1399-3054.1976.tb02258.x

Cited by 11 publications

(4 citation statements)

References 16 publications

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“…The pattern of a-ketoglutarate incorporation into the amino acid fraction of P-deficient lemon leaves is in agreement with our previous results: the delayed and low recovery of "'C in the amino acids, at the beginning, is apparently a consequence of the decreased activity of GOT caused by a decline in PLP concentration (2).…”

Section: Discussionsupporting

confidence: 92%

“…In P-deficient lemon seedlings we found an inverse relationship between their growth and arginine accumulation: as the rate of growth declined the concentration of arginine rose, while the other amino acids and protein remained low in comparison with seedlings grown in full nutrient solution (1). This deviation from the normal pattern of amino acid synthesis may be attributed to a decrease in activity of transaminases, enzymes which require pyridoxal phosphate as a coenzyme (2). In a study of the correlation among phosphate ratio, GOT2 activity, and PLP content, we found that the reduced activity of enzyme could be restored by infiltration of pyridoxal phosphate or mineral phosphate into the P-deficient leaves (2).…”

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confidence: 70%

“…This deviation from the normal pattern of amino acid synthesis may be attributed to a decrease in activity of transaminases, enzymes which require pyridoxal phosphate as a coenzyme (2). In a study of the correlation among phosphate ratio, GOT2 activity, and PLP content, we found that the reduced activity of enzyme could be restored by infiltration of pyridoxal phosphate or mineral phosphate into the P-deficient leaves (2). On the other hand, determinations oforganic acids disclosed extensive accumulation ofcitrate in P-deficient lemon leaves (unpublished data).…”

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confidence: 99%

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Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Achituv¹,

Bar‐Akiva²

1978

Plant Physiol.

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The uptake ad metabolism of a-15-14Clketoglutarate by phospborusdeficient and full nutrient (control) iemo (Citus lmn) leaves were studied over various thme intervals. After 45 minutes In P-deficient leaves, the bulk of Incorporated 14C appeared In organk acids and much less In amino acids, while In the control leaves, the 14C contests of organic and amino acids were equal. In P-efcient leaves, after loger Incubation times the 14C content of organic acids and anino acids Increased, whRe that of CO and residue fractions remaied iow. In full nutrient leaves the "C content of amino acids and organic acids decreased after ionger iocubaton time and Increased in the insolube residue and CO2. In full utient leaves the organic and amino acid metaboUsm were ciosely related and accompanied by protein synthesis and CO2 release, whie in P-deficient leaves an accelerating accumulation of arginine and citric acid was iHnked together With hibitio of protein syntheis and CO liberation.Accumulation of arginine is a well recognized metabolic disturbance induced by phosphorus deficiency in various plants (6,10,11,21). In P-deficient lemon seedlings we found an inverse relationship between their growth and arginine accumulation: as the rate of growth declined the concentration of arginine rose, while the other amino acids and protein remained low in comparison with seedlings grown in full nutrient solution (1). This deviation from the normal pattern of amino acid synthesis may be attributed to a decrease in activity of transaminases, enzymes which require pyridoxal phosphate as a coenzyme (2). In a study of the correlation among phosphate ratio, GOT2 activity, and PLP content, we found that the reduced activity of enzyme could be restored by infiltration of pyridoxal phosphate or mineral phosphate into the P-deficient leaves (2). On the other hand, determinations oforganic acids disclosed extensive accumulation ofcitrate in P-deficient lemon leaves (unpublished data).In the present study we followed the incorporation of a-ketoglutarate into various cell metabolities in P-deficient and normal citrus leaves. In each jar, a small vial containing 1.5 ml of methanol-ethanolamine (4:1, v/v), was placed to trap the "CO2.At the end of the incubation period the radioactivity of CO2 was counted in 10 ml of toluene fluor. During the incubation period, the jars were shaken gently in a water bath at 35 C. The incubation periods were 45, 90, and 180 min. Each combination of treatments (mineral nutrition and incubation period) was tested in three replicates.At the end of the incubation period the buffer solution was filtered through Miracloth. The discs were rinsed with deionized H20, blotted on filter paper, and boiled in 15 ml of 100%o ethanol for 10 min.Extraction. The discs were homogenized for 2 min in a VirTis blender set at speed 60, and centrifuged at 10,000g. The pellet was reextracted four times by shaking for 10 min with 10-ml portions of 80% (v/v) ethanol and then centrifuged (22).The insoluble residue was dried over silica ge...

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Section: Discussionsupporting

confidence: 92%

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confidence: 70%

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confidence: 99%

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Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Achituv¹,

Bar‐Akiva²

1978

Plant Physiol.

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“…Manganese infiltration. Infiltration was carried out in excised intact leaves under vacuum suction, as described by Achituv and Bar-Akiva (1976).…”

Section: Methodsmentioning

confidence: 99%

Effect of Manganese Deficiency on Chloroplasts of Lemon Leaves

Lerer

Bar‐Akiva

1979

Physiologia Plantarum

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Manganese deficiency in chloroplasts of Eureka lemon leaves resulted in 23% and 40% increase of chloroplasl nitrogen and protein, respectively, on a chlorophyll unit basis. Acrylamide gel electrophoresis carried out on extracts of these chloroplasts disclosed also qualitative differences between the normal and deficient leaves. Calculated on chloroplast N basis there is an increase of 17% in the chloroplast protein under Mn deficiency. This increase apparently indicates a more intense protein synthesis in the Mn deficient chloroplasts. Hill activity of the -Mn leaves was about one-third of the analog control leaves. Manganese infiltration into detached but intact leaves restored the activity in the -Mn leaves up to 70% of the control. Lemon leaves affected by other macro-and micro-nutrient deficiencies did not respond to the manganese infiltration; therefore, the use of this infiltration method is suggested for the evaluation of the manganese nutrition status of citrus and probably other higher plants.

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Nitrogen Metabolism and Utilization in Citrus

Kato

1986

Horticultural Reviews

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Glumatic‐Oxaloacetic Transaminase in Leaves of Phosphorus‐Deficient Citrus Plants

Cited by 11 publications

References 16 publications

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Effect of Manganese Deficiency on Chloroplasts of Lemon Leaves

Nitrogen Metabolism and Utilization in Citrus

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