The supply of reducing power for nitrite reduction in plastids of seedling pea roots (Pisum sativumL.)
✍ Scribed by Michael J. Emes; Michael W. Fowler
- Publisher
- Springer-Verlag
- Year
- 1983
- Tongue
- English
- Weight
- 590 KB
- Volume
- 158
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Plastids were separated from extracts of pea (Pisum sativum L.) roots by sucrose-densitygradient centrifugation. The incubation of roots of intact pea seedlings in solutions containing 10 mM KNO3 resulted in increased plastid activity of nitrite reductase and to a lesser extent glutamine synthetase. There were also substantial increases in the activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. No other plastidlocated enzymes of nitrate assimilation or carbohydrate oxidation showed evidence of increased activity in response to the induction of nitrate assimilation. Studies with [1-14C] -and [6-t4C]glucose indicated that there was an increased flow of carbon through the plastid-located pentose-phosphate pathway concurrent with the induction of nitrate assimilation. It is suggested that there is a close interaction through the supply and demand for reductant between the pathway of nitrite assimilation and the pentose-phosphate pathway located in the plastid.