Evidence for effects on the in vivo activity of ribulose-bisphosphate carboxylase/oxygenase during development of Mn toxicity in tobacco

• Published in: Plant physiology (Bethesda) 1988-04, Vol.86 (4), p.1143-1149
• Main Authors: Houtz, R.L, Nable, R.O, Cheniae, G.M
• Format: Article
• Language: English
• Subjects: 560300 - Chemicals Metabolism & Toxicology; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Agronomy. Soil science and plant productions; BIOCHEMICAL REACTION KINETICS; Biological and medical sciences; CARBON COMPOUNDS; Carbon cycle; CARBON DIOXIDE; CARBON OXIDES; CARBON-CARBON LYASES; CARBOXY-LYASES; CHALCOGENIDES; CHEMICAL REACTIONS; Chloroplasts; Economic plant physiology; ELEMENTS; Environmental and Stress Physiology; ENZYME ACTIVITY; ENZYMES; ENZYMIC ACTIVITY; ESTERASES; FITOTOXICIDAD; Fundamental and applied biological sciences. Psychology; HYDROLASES; IN VITRO; IN VIVO; KINETICS; LEAVES; LIASAS; LYASE; LYASES; MAGNOLIOPHYTA; MAGNOLIOPSIDA; MANGANESE; MANGANESO; Metabolism; METALS; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); NICOTIANA; NICOTIANA TABACUM; Nutrition. Photosynthesis. Respiration. Metabolism; OXIDES; OXYGEN COMPOUNDS; PHOSPHATASES; PHOTOCHEMICAL REACTIONS; PHOTOSYNTHESIS; Photosynthesis, respiration. Anabolism, catabolism; PHYTOTOXICITE; PHYTOTOXICITY; Plant physiology and development; PLANTS; Polyphenols; RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT; REACTION KINETICS; RIBULOSE DIPHOSPHATE CARBOXYLASE; SYNTHESIS; TOXICITY; TRANSITION ELEMENTS
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.86.4.1143

The progressive decrease in net photosynthesis accompanying development of Mn toxicity in young leaves of burley tobacco (Nicotiana tabacum L. cv KY 14) is a result of effects on in vivo activity of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (rubisco, EC 4.1.1.39). This conclusion is supported by: (a) decrease in rates of CO2 depletion during measurements of CO2 compensation, (b) increase in leaf RuBP concentrations, (c) progressive decreases in rate-constants of RuBP loss (light to dark transition analyses) with progressive increases of leaf Mn concentrations, and (d) restoration of diminished rates of net photosynthesis to control rates by elevated CO2 (5%). Moreover, elevated CO2 (1100 microliters per liter) during culture of Mn-treated plants decreased elevated RuBP concentrations to control levels and alleviated foliar symptoms of Mn toxicity. These effects of Mn toxicity on in vivo activity of rubisco were not expressed by in vitro kinetic analyses of rubisco prepared under conditions to sequester Mn or to adsorb polyphenols or their oxidation products. Similarly, the in vitro activity of fructose bisphosphatase (EC 3.1.3.11) was unaffected by Mn toxicity.