Early inhibition of photosynthesis during development of Mn toxicity in tobacco. [Nicotiana tabacum L. cv KY14]
- Univ. of Kentucky, Lexington (USA)
Early physiological effects of developing Mn toxicity in young leaves of burley tobacco (Nicotiana tabacum L. cv KY 14) were examined in glass-house/water cultured plants grown at high (summer) and low (winter) photon flux. Following transfer of plants to solutions containing 1 millimolar Mn{sup 2+}, sequential samplings were made at various times for the following 9 days, during which Mn accumulation by leaves increased rapidly from {approx} 70 on day 0 to {approx} 1700 and {approx} 5000 microgram per gram dry matter after 1 and 9 days, respectively. In plants grown at high photon flux, net photosynthesis declined by {approx} 20 and {approx} 60% after 1 and 9 days, respectively, and the onset of this decline preceded appearance (after 3 to 4 days) of visible foliar symptoms of Mn toxicity. Intercellular CO{sub 2} concentrations and rates of transpiration were not significantly affected. Though the activity of latent or activated polyphenol oxidase increased in parallel with Mn accumulation, neither leaf respiration nor the activity of catalase (EC 1.11.1.6) and peroxidase (EC 1.10.1.7) were greatly affected. These effects from Mn toxicity could not be explained by any changes in protein or chlorophyll abundance. Additionally, they were not a consequence of Mn induced Fe deficiency. Therefore, inhibition of net photosynthesis and enhancement of polyphenol oxidase activity are early indicators of excess Mn accumulation in tobacco leaves.
- OSTI ID:
- 6936497
- Journal Information:
- Plant Physiology; (USA), Vol. 86:4; ISSN 0032-0889
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MANGANESE
TOXICITY
NICOTIANA
PHOTOSYNTHESIS
BIOLOGICAL ACCUMULATION
CARBON DIOXIDE
CATALASE
CHLOROPLASTS
ENZYME ACTIVITY
INHIBITION
LEAVES
OXIDOREDUCTASES
SEASONAL VARIATIONS
TRANSPIRATION
CARBON COMPOUNDS
CARBON OXIDES
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
ENZYMES
MAGNOLIOPHYTA
MAGNOLIOPSIDA
METALS
OXIDES
OXYGEN COMPOUNDS
PEROXIDASES
PHOTOCHEMICAL REACTIONS
PLANTS
SYNTHESIS
TRANSITION ELEMENTS
VARIATIONS
560300* - Chemicals Metabolism & Toxicology