Inhibition of the Photosynthetic Capacity of Isolated Chloroplasts by Ozone

Coulson, Christopher; Heath, Robert L.

doi:10.1104/pp.53.1.32

Cited by 47 publications

(11 citation statements)

References 25 publications

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“…This is in contrast to the findings of Shreiber et al (26), who fumigated Phaseolus vulgaris with 300 or 500 nmol mole-' 03 for 6 h and deduced that the initial effects of 03 were on watersplitting activity. Electron transport in PSI PSII was found to be inhibited (2), but this inconsistency may be explained by the fact that Coulson and Heath (2) worked with isolated chloroplasts. The small reduction of Amax (10-29%) found here shows that the production of ATP and NADPH, required for the regeneration of RubP, was not severely affected.…”

Section: Analysis Of the Response Of A To Cmentioning

confidence: 99%

The Sequence of Change within the Photosynthetic Apparatus of Wheat following Short-Term Exposure to Ozone

et al. 1991

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The basis of inhibition of photosynthesis by single acute 03 exposures was investigated in vivo using analyses based on leaf gas exchange measurements. The fully expanded second leaves of wheat plants (Triticum aestivum L. cv Avalon) were fumigated with either 200 or 400 nanomoles per mole 03 for between 4 and 16 hours. This reduced significantly the light-saturated rate of CO2 uptake and was accompanied by a parallel decrease in stomatal conductance. However, the stomatal limitation, estimated from the relationship between CO2 uptake and the intemal CO2 concentration, only increased significantly during the first 8 hours of exposure to 400 nanomoles per mole 03; no significant increase occurred for any of the other treatments. Analysis of the response of CO2 uptake to the internal CO2 concentration implied that the predominant factor responsible for the reduction in lightsaturated CO2 uptake was a decrease in the efficiency of carboxylation. This was 58 and 21% of the control value after 16 hours at 200 and 400 nanomoles per mole 03, respectively. At saturating concentrations of C02, photosynthesis was inhibited by no more than 22% after 16 hours, indicating that the capacity for regeneration of ribulose bisphosphate was less susceptible to 03. Ozone fumigations also had a less pronounced effect on lightlimited photosynthesis. The maximum quantum yield of CO2 uptake and the quantum yield of oxygen evolution showed no significant decline after 16 hours with 200 nanomoles per mole 03, requiring 8 hours at 400 nanomoles per mole 03 before a significant reduction occurred. The photochemical efficiency of photosystem 11 estimated from the ratio of variable to maximum chlorophyll fluorescence and the atrazine-binding capacity of isolated thylakoids demonstrated that photochemical reactions were not responsible for the initial inhibition of CO2 uptake. The results suggest that the apparent carboxylation efficiency appears to be the initial cause of decline in photosynthesis in vivo following acute 03 fumigation.Ozone is widely recognized as a major air pollutant affecting crop yields ( 12

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Section: Analysis Of the Response Of A To Cmentioning

confidence: 99%

The Sequence of Change within the Photosynthetic Apparatus of Wheat following Short-Term Exposure to Ozone

et al. 1991

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“…Ozone was generated by UV irradiation of oxygen as described previously (3). Flow rate from the generator was 350 cc/min for all experiments.…”

Section: Methodsmentioning

confidence: 99%

Ozone-induced Fatty Acid and Viability Changes in Chlorella

Frederick

Heath²

1975

Plant Physiol.

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Ozone-treated cells of the photosynthetic green alga ChloreUa sorokiniana var. pacificensis exhibit an exponential decline in viability, as measured by their ability to form colonies on agar plates. Postexposure conditions appear to have little, if any, effect on this rate of decline. Except in young (early exponential phase) cells, culture age did not affect this rate. The decline in cell viability was correlated with the production of malondialdehyde, arising from the oxidative breakdown of an ozonide of unsaturated fatty acid material. The loss of fatty acids is substantiated by gas-liquid chromatography. A loss of 5 X 10`5 moles of fatty acid per cell corresponds to 75% nonviable cells after 50 minutes of ozone exposure.

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“…Ozone effects within the photosynthetic apparatus are variously attributed to damage of the CO2 fixation sites (22), damage of the Chl pigment system (4), and, according to Chimiklis and Heath (3) in studies with Chlorella, membrane damage causing leakage and subsequent ionic imbalance.…”

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confidence: 99%