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The regulation of glycolysis and electron transport in roots

The regulation of glycolysis and electron transport in roots The respiration of roots and isolated root mitochondria was investigated in Phaseolus vulgaris L., Spinacea oleracea L.; Triticum aestivum L., and Zea mays L. Although the respiration of both intact roots and isolated mitochondria displayed resistance to cyanide and sensitivity to SHAM, the percentage resistance and inhibition in roots was not the same as that in the mitochondria, with the exception of wheat. Adding FCCP to roots stimulated oxygen uptake and equalized the effects of SHAM and cyanide on roots and mitochondria. In spinach and maize roots, FCCP stimulated both the cytochrome and alternative pathways, while in bean roots, only the alternative pathway was stimulated. FCCP had little effect on wheat root respiration rates. Potential in vivo rates of oxygen uptake were estimated by expressing rates obtained with isolated mitochondria on a fumarase activity basis, and fumarase activity on a root weight basis. In wheat roots the potential rate was approximately equal to the measured in vivo rate; in the other species the potential rates were substantially greater than measured rates, but approximately equal to uncoupled in vivo rates. Key glycolytic intermediates in roots were measured, and it was found that the phosphofructokinase and pyruvate kinase reactions were displaced far from equilibrium, the degree of displacement being approximately equal in roots with little, and roots with substantial, alternative path engagement. Thus, although glycolysis is controlled, the regulation of this pathway appears to be quite flexible. The results are discussed in terms of possible regulatory mechanisms. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physiologia Plantarum Wiley

The regulation of glycolysis and electron transport in roots

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References (16)

Publisher
Wiley
Copyright
Copyright © 1983 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0031-9317
eISSN
1399-3054
DOI
10.1111/j.1399-3054.1983.tb04160.x
Publisher site
See Article on Publisher Site

Abstract

The respiration of roots and isolated root mitochondria was investigated in Phaseolus vulgaris L., Spinacea oleracea L.; Triticum aestivum L., and Zea mays L. Although the respiration of both intact roots and isolated mitochondria displayed resistance to cyanide and sensitivity to SHAM, the percentage resistance and inhibition in roots was not the same as that in the mitochondria, with the exception of wheat. Adding FCCP to roots stimulated oxygen uptake and equalized the effects of SHAM and cyanide on roots and mitochondria. In spinach and maize roots, FCCP stimulated both the cytochrome and alternative pathways, while in bean roots, only the alternative pathway was stimulated. FCCP had little effect on wheat root respiration rates. Potential in vivo rates of oxygen uptake were estimated by expressing rates obtained with isolated mitochondria on a fumarase activity basis, and fumarase activity on a root weight basis. In wheat roots the potential rate was approximately equal to the measured in vivo rate; in the other species the potential rates were substantially greater than measured rates, but approximately equal to uncoupled in vivo rates. Key glycolytic intermediates in roots were measured, and it was found that the phosphofructokinase and pyruvate kinase reactions were displaced far from equilibrium, the degree of displacement being approximately equal in roots with little, and roots with substantial, alternative path engagement. Thus, although glycolysis is controlled, the regulation of this pathway appears to be quite flexible. The results are discussed in terms of possible regulatory mechanisms.

Journal

Physiologia Plantarum – Wiley

Published: Jun 1, 1983

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