Multiple phytochromes are involved in red-light-induced enhancement of first-positive phototropism in Arabidopsis thaliana

The amplitude of phototropic curvature to blue light is enhanced by a prior exposure of seedlings to red light. This enhancement is mediated by phytochrome. Fluence-response relationships have been constructed for red-light-induced enhancement in the phytochrome A (phyA) null mutant, the phytochrome...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1997-03, Vol.113 (3), p.975-979
Main Authors: Janoudi, A. (Michigan State University, East Lansing, MI.), Gordon, W.R, Wagner, D, Quail, P, Poff, K.L
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Arabidopsis - physiology
Arabidopsis - radiation effects
ARABIDOPSIS THALIANA
Biological and medical sciences
Chromium
Curvature
Economic plant physiology
FITOCROMA
Fluence
Fundamental and applied biological sciences. Psychology
Hypocotyls
Irradiation
Light
LUMIERE
LUZ
Molecular Sequence Data
Movements
MUTANT
MUTANTES
Photoreceptors
Phototropism
PHYTOCHROME
Phytochrome - metabolism
Plant cells
Plant physiology and development
PLANTAS TRANSGENICAS
PLANTE TRANSGENIQUE
Plants, Genetically Modified
PLANTULAS
PLANTULE
Seedlings
Space life sciences
Transgenic plants
Tropism and nastic movements
TROPISME
TROPISMO
VARIACION GENETICA
VARIATION GENETIQUE
Whole Plant, Environmental, and Stress Physiology
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Summary:The amplitude of phototropic curvature to blue light is enhanced by a prior exposure of seedlings to red light. This enhancement is mediated by phytochrome. Fluence-response relationships have been constructed for red-light-induced enhancement in the phytochrome A (phyA) null mutant, the phytochrome B- (phyB) deficient mutant, and in two transgenic lines of Arabidopsis thaliana that overexpress either phyA or phyB. These fluence-response relationships demonstrate the existence of two responses in enhancement, a response in the very-low-to-low-fluence range, and a response in the high-fluence range. Only the response in the high-fluence range is present in the phyA null mutant. In contrast, the phyB-deficient mutant is indistinguishable from the wild-type parent in red-light responsiveness. These data indicate that phyA is necessary for the very-low-to-low but not the high-fluence response, and that phyB is not necessary for either response range. Based on these results, the high-fluence response, if controlled by a single phytochrome, must be controlled by a phytochrome other than phyA or phyB. Overexpression of phyA has a negative effect and overexpression of phyB has an enhancing effect in the high-fluence range. These results suggest that overexpression of either phytochrome perturbs the function of the endogenous photoreceptor system in an unpredictable fashion
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.113.3.975