Plant Physiol.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Plant Physiology 64:846-851 (1979)
© 1979 American Society of Plant Biologists

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Huber, S. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Huber, S. C.
Agricola
Right arrow Articles by Huber, S. C.
Articles

Orthophosphate Control of Glucose-6-Phosphate Dehydrogenase Light Modulation in Relation to the Induction Phase of Chloroplast Photosynthesis 1

Steven C. Huber

a United States Department of Agriculture, Science and Education Administration, Agricultural Research, Departments of Crop Science and Botany, North Carolina State University, Raleigh, North Carolina 27650

High concentrations of orthophosphate (Pi) inhibited CO2-dependent O2 evolution and prevented the inactivation of glucose-6-P dehydrogenase by light in intact spinach and barley chloroplasts. Addition of glycerate-3-P to chloroplasts inhibited by Pi in the light, induced O2 evolution and caused rapid inactivation of glucose-6-P dehydrogenase. The activity of phosphofructokinase detected in chloroplast preparations was not affected by light or by Pi.

Dihydroxyacetone-P was a major product of chloroplast photosynthesis when optimum concentrations of Pi were used. Chloroplasts continued to form dihydroxyacetone-P at a slow rate in the presence of Pi at concentrations (2 to 4 millimolar) that gave complete inhibition of CO2-dependent O2 evolution. Formation of dihydroxyacetone-P in the presence of 4 millimolar Pi was stimulated by light and either O2 (150 micromolar) or sparker amounts of oxaloacetate.

Conditions that favored dihydroxyacetone-P formation (high O2 or low O2 plus oxaloacetate) increased the optimum Pi concentration for CO2-dependent O2 evolution and stimulated O2 evolution at high concentrations of Pi. The stimulation of O2 evolution at superoptimal concentrations of Pi by O2 or oxaloacetate was prevented by dithiothreitol.

The results suggested that formation of pentose-P pathway intermediates via the oxidative pentose-P pathway may be limited by availability of NADP in the light but may occur at significant rates and thereby contribute to termination of the induction phase of O2 evolution.

1 Cooperative investigations of the North Carolina Agriculture Research Service and the Science and Education Administration, United States Department of Agriculture, Raleigh, North Carolina. Paper No. 5998 of the Journal Series of the North Carolina Agriculture Research Service, Raleigh, North Carolina.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 1979 by the American Society of Plant Biologists