Sequential Induction of Phenylalanine Ammonia-lyase and a Lyase-inactivating System in Potato Tuber Disks

Zucker, Milton

doi:10.1104/pp.43.3.365

Cited by 207 publications

(90 citation statements)

References 24 publications

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“…As with other inducible enzymes in eukaryote systems (5,16,17,20,21,24), this pattern of induction suggests the involvement of activating and inactivating systems which are responsive to both the level of co-inducer, in this case nitrate, and repressor, in this case unknown. In fungi where genetic and biochemical features have been examined in detail several unlinked genetic loci are responsible for the structure and induction properties of nitrate reductase (1,18,19 In agreement with earlier work (8,17,21), our results show that both RNA and protein synthesis are important in the induction.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Turnover of Nitrate Reductase in Corn Roots

1972

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The induction and reinduction of nitrate reductase in root tip or mature root sections show essentially a similar pattern: a lag, a period of rapid increase in enzyme activity and finally a period of relatively minor change. Both (8,17,21) for the induction of nitrate reductase. In addition they show that as root cells age the enzyme becomes less stable. MATERIALS AND METHODSThe seeds of Zea mays (Wf9 X 38-1 1) were surface sterilized by a brief treatment with Javex, a commercial bleach containing 6.0% NaOCl. They were planted under sterile conditions on nitrate-free 0.9% agar which contained one-tenth strength Hoagland solution and an additional supplement of molybdenum (0.02 ,ug/ml). The 26 C before transfer to nitrate induction media. At this time the primary root was approximately 5 cm long. Roots growing on the surface of the agar were selected. The nitrate induction solution contained 5 or 10 mm nitrate, levels which gave a good induction of nitrate reductase but which did not saturate the system either with respect to enzyme synthesis or accumulation of nitrate (Wallace and Oaks unpublished results). In addition, in long term experiments, these concentrations of nitrate did not inhibit growth of the primary root (Wallace and Oaks unpublished results). The inhibitor compounds tested were made up in solution just before use and the pH of the induction solutions was adjusted to 5.8. The experiments were conducted at 26 C in the dark. In all cases, intact seedlings were used and the primary root was sectioned only after the experimental treatment had been completed. The 0-to 10-mm and the 25-to 35-mm root sections were harvested at appropriate time intervals.Extraction Procedure. Root tips and mature root sections were routinely frozen in liquid nitrogen, weighed, and stored at -20 C overnight. They were extracted with four volumes relative to weight of 50 mm phosphate buffer at pH 7.5. The buffer contained 0.5 mm EDTA and 5 mm cysteine. For enzyme preparations used in the in vitro inactivation, root tip sections were extracted as above, whereas the mature sections were extracted with two volumes of buffer. This had no effect on the specific activity of the enzyme, but insured that the protein levels in the two extracts were similar. The extracts were centrifuged at 30,000g for 30 min.Assay Methods. The assay mixture for nitrate reductase was as follows: phosphate, pH 7.8, 90 ,moles; KNO,,20 ,umoles; NADH, 1

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Section: Discussionmentioning

confidence: 99%

Synthesis and Turnover of Nitrate Reductase in Corn Roots

1972

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“…The available evidence suggests that the increase in activity is due to synthesis of new protein and not to activation of a pre-existing protein (1,24). Recently, evidence has accumulated that the loss of activity is also an active process (14,20,23,24). The addition of cycloheximide to maize leaf sheaths prevented the loss of PAL activity normally observed in excised tissue (14,16).…”

Section: Methodsmentioning

confidence: 99%

“…The reduction in activity, however, was smaller and less consistent than that of the other enzymes studied. Both nitrate reductase and PAL are reported to be enzymes formed and inactivated within a few hours and subject to control mechanisms which as yet are only poorly understood (3, 1 1,17,23,24). A number of factors lead to enhanced activity of both enzymes.…”

Section: Methodsmentioning

confidence: 99%

Effects of Water Stress on the Activities of Three Enzymes in Maize Seedlings

Bardzik¹,

Marsh²,

Havis³

1971

Plant Physiol.

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Changes in the activities of three enzymes (nitrate reductase, L-phenylalanine ammonia-lyase, and a dehydronicotinamide adenine dinucleotide-oxidase complex) were measured during development of water stress in young maize (Zea mays) plants.L-Phenylalanine ammonia-lyase and nitrate reductase activities decreased markedly with water deficits of 10 to 20%. 'Abbreviation: PAL, L-phenylalanine ammonia-lyase. MATERIALS AND METHODSThe dominant tall form of the d1 dwarf maize (Zea mays) was grown in vermiculite in the greenhouse. Nutrient requirements were provided with a modified Hoagland's solution 1 (9). Moisture stress was initiated by withholding water for varying periods beginning approximately 10 days after germination. In early experiments, the plants remained in the greenhouse until sampled for assay, but in later experiments they were transferred to a growth chamber when water stress was initiated. The chamber environment was 27 C, 30 to 50% relative humidity, and had a light period of 12 hr/day of 1000 ft-c. The plants were sampled at the middle of the light period. In the rehydration experiments, the vermiculite base was saturated with water 24 hr prior to sampling.Water deficit was estimated by the method of Weatherly (21). Duplicate or triplicate 5-cm sections were taken from the midportion of the third leaf of two or three plants. The original weight was determined immediately after harvest, and the tissue was floated in deionized water for 4 hr. At that time, the saturated weight was taken and the tissue was dried at 95 C for 24 hr for dry weight determination. The water deficit was expressed as the ratio of water taken up divided by the final water content, multiplied by 100.The midportion of the leaf blades from four to six seedlings was used as the source of tissue for nitrate reductase and NADH oxidase. PAL was prepared from the leaf sheaths of the same or comparable seedlings. Nitrate reductase activity was determined by the method of Hageman and Flesher (6), except that the tissue was ground in a chilled mortar with pestle and sand. PAL was prepared and assayed as described by Reid and Marsh (15). NADH oxidase activity was determined in the same extract used for nitrate reductase. The reaction mixture for the oxidase assay contained 200 ymoles of tris buffer, pH 8.2; 20 ,tmoles of (NH4)2SO4; 0.66 umole of NADH; plus enzyme in a final volume of 3 ml. The reaction was run at 30 C and was initiated by the addition of NADH. Changes in absorbancy at 340 nm were followed spectrophotometrically for 5 min.One unit of activity for all three enzymes was defined as the amount of enzyme which catalyzed the formation of 1 ,tmole of product in 1 min under standard conditions. Protein was determined by standard biuret or Lowry methods (12) with bovine serum albumin as a standard. RESULTSThe results of water deficit measurements (Fig. 1)

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“…However, with the exception of phenylalanine ammonia-lyase (E.C. 4.3.1.5), which has been extensively purified (7) and studied (2,4,8,18,19,22,26,31,32), and is implicated as one controlling agent in lignification (10,29,30), there is relatively little information regarding most of the enzymatic reactions involved (3,23,24). Consequently, the factors which control lignification are poorly understood but appear to vary with environmental conditions (21), developmental stage (11,23,25) and the species of the plant (23,24).…”

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confidence: 99%

Gibberellic Acid-Promoted Lignification and Phenylalanine Ammonia-lyase Activity in a Dwarf Pea (Pisum sativum)

Cheng

Marsh

1968

Plant Physiol.

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Abstract. The effects of gibberellic acid on lignification in seedlings of a dwarf and a tall cultivar of pea (Pisum sativum) grown under red or white light or in the darkness, were studied. Gibberelilic acid (10-6-10-4 M) promoted stem elongation in both light and dark and increased the percentage of lignin in the stems of the light-grown dwarf pea. The gibberellin had no effect oil the lignin content of the tall pea although high concentrations (10-4 M) promoted growth of the itaill plants. Time course studies indicated ithat the enhanced lignification in the gibberellin-treated dwarf plants occurred only after a lag period of several days.It was concluded that gibberellic acid-enhanced lignification had no direct relation to gibberellic acid-promoted growth. The activity of phenylalanine ammonia-lyase (E.C. 4.3.1.5) was higher in gibberellin-treated dwerf plants grown under white or red light than in untreated dwarf plants. Gibberellic acid had no detectable effect on the activity of this enzyme when the plants were grown in darkness, just as it had no effect on lignification under dark conditions.The data suggest that in gibberellin-deficient peas the activitv of phen)lalanine ammonia-slyase is one of the limiting factors in lignification.

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Sequential Induction of Phenylalanine Ammonia-lyase and a Lyase-inactivating System in Potato Tuber Disks

Abstract: Abstract. The light induced synthesis of phenylalanine ammonia-lyase in disks cut from potato tubers is very sensitive to cycloheximide. Synthesis is inhibited 50 % in disks cultured on 5/,M cycloheximide instead of water and almost completely in disks aged in

Cited by 207 publications

References 24 publications

Synthesis and Turnover of Nitrate Reductase in Corn Roots

Synthesis and Turnover of Nitrate Reductase in Corn Roots

Effects of Water Stress on the Activities of Three Enzymes in Maize Seedlings

Gibberellic Acid-Promoted Lignification and Phenylalanine Ammonia-lyase Activity in a Dwarf Pea (Pisum sativum)

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