Response of Cytosolic-Isozyme and Plastid-Isozyme Levels of 3-Deoxy-d-Arabino-Heptulosonate 7-Phosphate Synthase to Physiological State of Nicotiana silvestris in Suspension Culture

• Published in: Plant physiology (Bethesda) Vol. 83; no. 3; pp. 479 - 482
• Main Authors: Robert J. Ganson, Jensen, Roy A.
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.03.1987
• Subjects: Agronomy. Soil science and plant productions; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cell growth; Cell physiology; Communications; Cultured cells; Economic plant physiology; Enzymes; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Geometric growth; L cells; Ligases; Nutrition. Photosynthesis. Respiration. Metabolism; Plant cells; Plants; Population growth; Steepest descent method; Subcultures; Cell culture; Vegetals; Nicotiana; Enzyme; Isozyme; Biosynthesis; Assay; Suspension culture; Dicotyledones; Angiospermae; Spermatophyta; Solanaceae; Localization
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.83.3.479

Two isozymes of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase are partitioned into plastid (DS-Mn) and cytosolic (DS-Co) compartments of at least several higher plants (RA Jensen 1986 Rec Adv Phytochem 20: 257-258). Differential variation of isozyme levels and in the timing of their expression was observed during growth of Nicotiana silvestris in suspension culture. The ratio of DS-Co to DS-Mn varied about fivefold in comparison of the different physiological stages of growth. Cultures maintained in exponential phase for >10 generations (EE cells) possessed balanced-growth properties and did not exhibit the considerable variation of isozyme levels found during the initial 2 to 3 generations of exponential growth (E cells) that followed subculture of stationary-phase cultures. The plastid isozyme level declined substantially in stationary phase, responded immediately to subculture, and reached a peak in early exponential growth similar to the steady-state level of DS-Mn in EE cells. In contrast, the cytosolic isozyme level peaked in late exponential growth. A recent history of stationary-phase physiology appeared to foster elevated synthesis of DS-Co since the steady-state level of DS-Co in EE cells was much lower than in E cells.