Plant and Soil

, Volume 77, Issue 1, pp 127–130 | Cite as

Nitrate reductase and glutamine synthetase activity in leaves and roots of nitrate-fedHelianthus annuus L.

  • J. J. Kaiser
  • O. A. M. Lewis
Short Communication


It has been reported that in plants of nitrate-fedH. annuus, nitrate reductase activity (NRA) is restricted to the roots of the plant. With an improved extraction technique using a medium containing 2% casein and 1.5 g insoluble polyvinylpyrrolidone (PVP) per gram material, however, the leaves ofH. annuus showed a far greaterin vitro NRA (24.7±0.4 μmoles h−1 g fr.wt.−1) than did the roots (3.4±0.6 μmoles h−1 g fr.wt.−1).In vitro glutamine synthetase activity (GSA) was found to be greater in the leaves (27 μmoles h−1 g fr. wt.−1) than the root (5.6 μmoles h−1 g fr.wt.−1) using a standard extraction medium. With the addition of casein and PVP to the extraction medium, GSA increased to 141 μmoles h−1 g fr.wt.−1 in the leaves and 23 μmoles h−1 g fr.wt.−1 in the roots.

It is thus essential to include both casein and PVP in the extracting medium of leaves and roots ofH. annuus when determiningin vitro NRA and GSA.

Key words

Glutamine synthetase Helianthus N utilization Nitrate Nitrate reduction 



glutamine synthetase activity


nitrate reductase activity




bovine serum albumin


nitrate reductase


glutamine synthetase


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Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1984

Authors and Affiliations

  • J. J. Kaiser
    • 1
  • O. A. M. Lewis
    • 1
  1. 1.Department of Botany, Faculty of ScienceUniversity of Cape TownP/B RondeboschRepublic of South Africa

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