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The relationship between photosynthetic electron transport and photorespiratory 14 CO 2 release after DCMU treatment in the duckweed, Lemna gibba
Author(s) -
Chaturvedi Rekha,
Haugstad May K.,
Nilsen Stein
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb04894.x
Subject(s) - dcmu , photorespiration , photosynthesis , lemna gibba , electron transport chain , photosystem , photosystem ii , photochemistry , chemistry , oxygen evolution , ferricyanide , oxygen , biophysics , biology , biochemistry , aquatic plant , ecology , macrophyte , organic chemistry , electrode , electrochemistry
The photosynthetic rate of Lemna gibba was measured as 14 CO 2 uptake at the beginning of and after 1 h DCMU treatment during the separate excitation of PS I (703 nm), mainly PS II (662 nm) and the combined excitation of both photosystems (662 + 703 nm) in 2 and 21% oxygen. The results show the Warburg effect. Photosynthesis was significantly reduced by DCMU whenever PS II was excited, at 662 nm and 662 + 703 nm. Photosynthetic enhancement was greater in 21 than in 2% oxygen in both the treated and untreated plants. Photorespiratory 14 CO 2 release was only affected by DCMU treatment at 662 + 703 nm. It was significantly decreased in 21% O 2 and significantly increased in 2% O 2 as compared to the controls without DCMU. The 14 C‐glycolate remaining in the plant after photosynthesis/photorespiration measurements was reduced whenever the electron supply to PS I was low. These data support the hypothesis that a relationship exists between glycolate metabolism and photosynthesis via the electron transport chain where electrons from the oxidation of glycolate are donated to PS I when the electron supply from water is low.