The induction of nitrate reductase and the preferential assimilation of ammonium in germinating rice seedlings.

Shen, T C (1969) The induction of nitrate reductase and the preferential assimilation of ammonium in germinating rice seedlings. Plant physiology, 44 (11). pp. 1650-5. ISSN 0032-0889

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Abstract

Nitrate reduotase is induced by nitrate in excised embryos and germinating intact seedlings of rice (Oryza sativa L.). The enzyme is induced 24 hr after imbibition. The rate of enzyme formation increases with the age of seedlings. There is a lag period of 30 to 40 min between the addition of substrate and the formation of nitrate reductase. Formation of the enzyme is promoted by the presence of ammonium. Chloramphenicol, actinomycin D and cycloheximide effectively inhibit the formation of nitrate reductase.Rice seedlings can assimilate nitrate from the beginning of germination. However, the utilization of nitrate is completely suppressed by the presence of ammonium. As soon as ammonium is depleted from the medium, nitrate utilization is resumed. Ammonium inhibits the first step of nitrate reduction, i.e., NO(-) (3) --> NO(-) (2), but does not inhibit the assimilation of nitrite. This provides an example of feedback inhibition in higher plants.

Item Type: Article
Creators:
  1. Shen, T C
Journal or Publication Title: Plant physiology
Uncontrolled Keywords: nitrate reductase
Subjects: R Medicine > R Medicine (General)
Divisions: Faculty of Science > Institute of Biological Sciences
Depositing User: Mr. Faizal Hamzah
Date Deposited: 01 Mar 2011 09:35
Last Modified: 01 Mar 2011 09:35
URI: http://eprints.um.edu.my/id/eprint/228

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