A light-enhanced metabolism of sulfite in cells of Cucumis sativus L. cotyledons |
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Authors: | B Rothermel R Alscher |
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Institution: | (1) Boyce Thompson Institute for Plant Research at Cornell University, Tower Road, 14853 Ithaca, NY, USA;(2) Present address: Biology Department, Yale University, 06520 New Haven, CT, USA |
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Abstract: | The effects of light and several photosynthetic inhibitors on the rate of sulfite metabolism in cells obtained from Cucumis sativus L. cotyledons was studied. The cells were treated with 200 M Na2SO3 and the disappearance of sulfite was monitored using either dithiobisnitrobenzoic acid or fuchsin. The rate of sulfite disappearance in light was double the dark rate. Disalicylidene propanediamine at 1 mM increased this light-enhanced metabolism approx. 50%; neither 1 M 3,4-dichlorophenyl-N,N-dimethylurea nor 0.1 mM cyanazine, which completely inhibited CO2-dependent oxygen evolution, affected the rate of sulfite metabolism. Addition of 200 M Na2SO3 to the cells partially inhibited 14CO2 fixation. The rate of sulfite consumption by the cells did not affect this inhibition. We conclude that light-dependent sulfite metabolism is cucumber cells may utilize reduced ferredoxin generated as a result of photosynthetic electron transport. An injurious interaction between CO2 fixation and sulfite appears to occur independently of the sulfite-metabolism process.Abbreviations DCMU
3,4-dichlorophenyl-N,N-dimethylurea
- DSPD
disalicylidene propanediamine
- DTNB
5,5 -dithiobis-(2-nitrobenzoic acid) |
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Keywords: | Cucumis (sulfite metabolism) Photosynthesis (SO2 inhibition) Sulfite metabolism |
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