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Photoregulation of the Greening Process of Wheat Seedlings Grown in Red Light*

Photoregulation of the Greening Process of Wheat Seedlings Grown in Red Light* Wheat seedling grown with their shoot bottom exposed to red light (400 μmol m−2 s−1) either with constant illumination or light-dark cycles did not accumulate chlorophyll. This near-etiolation response was manifested by a critical threshold intensity of red light and did not need continuous illumination. The inhibition of the greening process resulted from reduced synthesis of glutamate-1-semialdehyde and consequent reduction in tetrapyrrole precursor 5-aminolevulinic acid. Red light perceived by the shoot bottom down regulated the protein and/or gene expression of enzymes involved in the biosynthesis of tetrapyrroles. The contents of endogenous cytokinins, i.e., isopentenyl-adenosine and dihydrozeatinriboside, were reduced in seedlings grown in red light having their shoot bottom exposed. Application of exogenous cytokinin and its analogue to roots of seedlings grown in red light reversed the down regulation of the greening process. The reversal of red-light-induced near-etiolation morphogenesis by far-red (200 μmol m−2 s−1) or blue (25 μmol m−2 s−1) light suggests that it could be a very high red-irradiance response of phytochrome, in the meristematic layers of the shoot bottom, that works in concert with blue light receptor(s). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

Photoregulation of the Greening Process of Wheat Seedlings Grown in Red Light*

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References (70)

Publisher
Springer Journals
Copyright
Copyright © 2005 by Springer
Subject
Life Sciences; Biochemistry, general; Plant Sciences; Plant Pathology
ISSN
0167-4412
eISSN
1573-5028
DOI
10.1007/s11103-005-8880-2
pmid
16247557
Publisher site
See Article on Publisher Site

Abstract

Wheat seedling grown with their shoot bottom exposed to red light (400 μmol m−2 s−1) either with constant illumination or light-dark cycles did not accumulate chlorophyll. This near-etiolation response was manifested by a critical threshold intensity of red light and did not need continuous illumination. The inhibition of the greening process resulted from reduced synthesis of glutamate-1-semialdehyde and consequent reduction in tetrapyrrole precursor 5-aminolevulinic acid. Red light perceived by the shoot bottom down regulated the protein and/or gene expression of enzymes involved in the biosynthesis of tetrapyrroles. The contents of endogenous cytokinins, i.e., isopentenyl-adenosine and dihydrozeatinriboside, were reduced in seedlings grown in red light having their shoot bottom exposed. Application of exogenous cytokinin and its analogue to roots of seedlings grown in red light reversed the down regulation of the greening process. The reversal of red-light-induced near-etiolation morphogenesis by far-red (200 μmol m−2 s−1) or blue (25 μmol m−2 s−1) light suggests that it could be a very high red-irradiance response of phytochrome, in the meristematic layers of the shoot bottom, that works in concert with blue light receptor(s).

Journal

Plant Molecular BiologySpringer Journals

Published: Jun 17, 2005

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