Factors affecting the enhancement of oxidative stress tolerance in transgenic tobacco overexpressing manganese superoxide dismutase in the chloroplasts

• Published in: Plant physiology (Bethesda) Vol. 107; no. 3; pp. 737 - 750
• Main Authors: Slooten, Luit, Katelijne Capiau, Van Camp, Wim, Van Montagu, Marc, Chris Sybesma, Inzé, Dirk
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-03-1995; Oxford University Press ; American Society of Plant Biologists
• Subjects: acide ascorbique; acido ascorbico; actividad enzimatica; activite enzymatique; Agronomy. Soil science and plant productions; antioxidantes; antioxidants; antioxydant; ascorbic acid; Biological and medical sciences; chemical composition; chlorophylle; chlorophylls; chloroplaste; Chloroplasts; citoplasma; clorofilas; cloroplasto; composicion quimica; composition chimique; crecimiento; croissance; cytoplasm; cytoplasme; developmental stages; Economic plant physiology; Enzyme substrates; Enzymes; enzymic activity; etapas de desarrollo; expresion genica; expression des genes; feuille; free radicals; Fundamental and applied biological sciences. Psychology; gene expression; genetic variation; Genetics; glutathion; glutathione; glutation; growth; hojas; leaves; Life Sciences; light; lumiere; Luminous intensity; luz; manganese; manganeso; Metabolism; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); nicotiana tabacum; Nutrition. Photosynthesis. Respiration. Metabolism; oxidantes; oxidants; Oxidative stress; oxidoreductases; oxidorreductasas; oxigeno; oxydant; oxydoreductase; oxygen; oxygene; peroxidasas; peroxidases; peroxydase; Photosynthesis, respiration. Anabolism, catabolism; Plant growth; Plant physiology and development; plantas transgenicas; plante transgenique; Plants; Plants genetics; radical libre; radicales libres; Reactive oxygen species; stade de developpement; superoxide dismutase; Superoxides; superoxido dismutasa; superoxyde dismutase; Transgenic plants; variacion genetica; variation genetique; variedades; variete; varieties; Whole Plant, Environmental, and Stress Physiology; Oxidative stress; Enzyme; Gene overexpression; Tolerance; Stimulant plant; Superoxide dismutase; Antioxidant; Nicotiana tabacum; Luminous intensity; Dicotyledones; Angiospermae; Transgenic plant; Spermatophyta; Oxidoreductases; Solanaceae; Photooxidation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.107.3.737

Two varieties of tobacco (Nicotiana tabacum var PBD6 and var SR1) were used to generate transgenic lines overexpressing Mn-superoxide dismutase (MnSOD) in the chloroplasts. The overexpressed MnSOD suppresses the activity of those SODs (endogenous MnSOD and chloroplastic and cytosolic Cu/ZnSOD) that are prominent in young leaves but disappear largely or completely during aging of the leaves. The transgenic and control plants were grown at different light intensities and were then assayed for oxygen radical stress tolerance in leaf disc assays and for abundance of antioxidant enzymes and substrates in leaves. Transgenic plants had an enhanced resistance to methylviologen (MV), compared with control plants, only after growth at high light intensities. In both varieties the activities of FeSOD, ascorbate peroxidase, dehydroascorbate reductase, and monodehydroascorbate reductase and the concentrations of glutathione and ascorbate (all expressed on a chlorophyll basis) increased with increasing light intensity during growth. Most of these components were correlated with MV tolerance. It is argued that SOD overexpression leads to enhancement of the tolerance to MV-dependent oxidative stress only if one or more of these components is also present at high levels. Furthermore, the results suggest that in var SR1 the overexpressed MnSOD enhances primarily the stromal antioxidant system.