The alternative oxidase in roots of Poa annua after transfer from high‐light to low‐light conditions

Summary The activity of the alternative pathway can be affected by a number of factors, including the amount and reduction state of the alternative oxidase protein, and the reduction state of the ubiquinone pool. To investigate the importance of these factors in vivo, we manipulated the rate of root...

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Published in:	The Plant journal : for cell and molecular biology Vol. 23; no. 5; pp. 623 - 632
Main Authors:	Millenaar, Frank F., Roelofs, Roeland, Gonzàlez‐Meler, Miquel A., Siedow, James N., Wagner, Anneke M., Lambers, Hans
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Science Ltd 01-09-2000 Blackwell Science
Subjects:	alternative oxidase Biological and medical sciences Carbohydrate Metabolism Electron Transport Complex IV - metabolism Fundamental and applied biological sciences. Psychology Light Metabolism Mitochondrial Proteins Oxidoreductases - metabolism Oxygen - metabolism Photosynthesis, respiration. Anabolism, catabolism Plant physiology and development Plant Proteins Plant Roots - enzymology Plant Roots - metabolism Plant Roots - radiation effects root respiration sugars Ubiquinone - metabolism Monocotyledones Weed Root Enzyme Oxidase Cytochrome-c oxidase Poa annua Photoperiod In vitro Ubiquinone Enzymatic activity Gramineae Light Angiospermae Spermatophyta Carbohydrate Oxidoreductases Biological accumulation Cell respiration
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Summary:	Summary The activity of the alternative pathway can be affected by a number of factors, including the amount and reduction state of the alternative oxidase protein, and the reduction state of the ubiquinone pool. To investigate the importance of these factors in vivo, we manipulated the rate of root respiration by transferring the annual grass Poa annua L. from high‐light to low‐light conditions, and at the same time from long‐day to short‐day conditions for four days. As a result of the low‐light treatment, the total respiration rate of the roots decreased by 45%, in vitro cytochrome c oxidase capacity decreased by 49%, sugar concentration decreased by 90% and the ubiquinone concentration increased by 31%, relative to control values. The absolute rate of oxygen uptake via the alternative pathway, as determined using the 18O‐isotope fractionation technique, did not change. Conversely, the cytochrome pathway activity decreased during the low‐light treatment; its activity increased upon addition of exogenous sugars to the roots. Interestingly, no change was observed in the concentration of the alternative oxidase protein or in the reduction state of the protein. Also, there was no change in the reduction state of the ubiquinone pool. In conclusion, the concentration and activity of the alternative oxidase were not changed, even under severe light deprivation.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0960-7412 1365-313X
DOI:	10.1046/j.1365-313x.2000.00832.x