Document Detail

Ozone Inhibition of Photosynthesis in Chlorella sorokiniana.
MedLine Citation:
PMID:  16662164     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Exposure of Chlorella sorokiniana (07-11-05) to ozone inhibits photosynthesis. In this study, the effects of ozone on O(2) evolution and fluorescence yields are used to characterize this inhibition. At an ozone dose of about 3 micromoles delivered to 2 x 10(9) cells, the photosynthetic rate of the cells is inhibited 50%, as indicated by a decrease in bicarbonate-stimulated O(2) evolution (control rate, 1.4 +/- 0.3 x 10(-15) moles per cell per minute).Normal patterns of chlorophyll fluorescence are also altered. Upon continuous exposure to ozone (3.5 x 10(-7) moles O(3) per minute), three stages of change in relative fluorescence yields are observed: (a) a rise in variable yield with no corresponding change in nonvariable yield (after 1-2 minutes), which was interpreted to be a shift in the energy flow pathway; (b) a decline in variable yield with a slight rise in nonvariable yield (requiring 3-5 minutes), interpreted to be a blockage in the CO(2) fixation pathways; and (c) complete blockage of variable yield with a concurrent decline in nonvariable yield (8-10 minutes), interpreted to be a destruction of the pigment system. The timing of each stage depended upon the ozone concentration and its delivery rate to the cell suspension. These results are compared with ozone-induced decline in photosynthesis and leaf water potential changes reported for other plant systems.Evidence is also presented to suggest that ozone effects on the photosynthetic processes are attributable to ionic imbalances brought about by ozone interaction with the plasmalemma rather than a direct effect on the chloroplast.
R L Heath; P E Frederick; P E Chimiklis
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Plant physiology     Volume:  69     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  1982 Jan 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-06-29     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  229-33     Citation Subset:  -    
Department of Botany and Plant Sciences, University of California, Riverside, California 92521.
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