title: The supply of reducing power for nitrite reduction in plastids of seedling pea roots (Pisum sativum L.).
abstract: Plastids were separated from extracts of pea (Pisum sativum L.) roots by sucrose-density-gradient 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 plastid-located enzymes of nitrate assimilation or carbohydrate oxidation showed evidence of increased activity in response to the induction of nitrate assimilation. Studies with [1-(14)C]-and [6-(14)C]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.
authors.affiliation: Wolfson Unit of Plant Cell Biotechnology, Department of Biochemistry, The University, S10 2TN, Sheffild, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Emes
authors.forename: M W
authors.initials: MW
authors.lastname: Fowler