Chlorophyll Fluorescence Assay for Ozone Injury in Intact Plants

Schreiber, Ulrich; Vidaver, William; Runeckles, V. C.; Rosen, Peter

doi:10.1104/pp.61.1.80

Cited by 156 publications

(41 citation statements)

References 12 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.…”

Section: Analysis Of the Response Of A To Ccontrasting

confidence: 55%

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 Ccontrasting

confidence: 55%

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

et al. 1991

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“…Coulson and Heath (6) have shown that ozone does not uncouple ATP synthesis even under conditions where electron transport is inhibited. Schreiber et al (26) report that electron transport between photosystems is eventually inhibited after ozone exposure and that the extent of injury depends on concentration of pollutant, exposure time, and leafage. It is improbable, therefore, that the reduction of carbon uptake observed in our system was due to a lack of ATP and/or reductant.…”

Section: Discussionmentioning

confidence: 99%

Response of Photosynthesis and Cellular Antioxidants to Ozone in Populus Leaves

Gupta¹,

Alscher²,

McCune³

1991

Plant Physiol.

122

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Atmospheric ozone causes formation of various highly reactive intermediates (e.g. peroxyl and superoxide radicals, H202, etc.) in plant tissues. A plant's productivity in environments with ozone may be related to its ability to scavenge the free radicals formed. The effects of ozone on photosynthesis and some free radical scavengers were measured in the fifth emergent leaf of poplars. Clonal poplars (Populus deltoides x Populus cv caudina) were fumigated with 180 parts per billion ozone for 3 hours. Photosynthesis was measured before, during, and after fumigation. During the first 90 minutes of ozone exposure, photosynthetic rates were unaffected but glutathione levels and superoxide dismutase activity increased. After 90 minutes of ozone exposure, photosynthetic rates began to decline while glutathione and superoxide dismutase continued to increase. Total glutathione (reduced plus oxidized) increased in fumigated leaves throughout the exposure period. The ratio of GSH/GSSG also decreased from 12.8 to 1.2 in ozone exposed trees. Superoxide dismutase levels increased twofold in fumigated plants. After 4 hours of ozone exposure, the photosynthetic rate was approximately half that of controls while glutathione levels and superoxide dismutase activity remained above that of the controls. The elevated antioxidant levels were maintained 21 hours after ozone exposure while photosynthetic rates recovered to about 75% of that of controls. Electron transport and NADPH levels remained unaffected by the treatment. Hence, elevated antioxidant metabolism may protect the photosynthetic apparatus during exposure to ozone.All organisms that have evolved in aerobic environments have a variety of enzymatic and nonenzymatic mechanisms to prevent oxidation of cellular components. It is quite probable that existing mechanisms for detoxifying oxyradicals are invoked in response to ozone since it causes the formation of some highly reactive oxyradicals in aqueous solutions, a major product being the superoxide anion (I1). The superoxide anion can be metabolized by several isozymes of superoxide dismutase found in plants (14). The hydrogen peroxide formed by this reaction is toxic. It can inactivate -SH containing enzymes (5, 13) or react with superoxide to form the hydroxyl radical, which can attack many macromolecular

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“…8 ' 9 Reduced photosynthesis in plants exposed to O3 is a commonly reported response. 10 " 16 The more rapid decline in photosynthesis associated with increasing O3 dose in class III, compared with class I trees, would be expected if stomatal conductance in current needles were the primary factor regulating O3 injury. Early in the first season of growth (July and August), class III current needles had significantly greater stomatal conductances (16%) than did class I needles ( Figure 2).…”

Section: Discussionmentioning

confidence: 99%