Distorted phytochrome action spectra in green plants.
1Department of Botany, Plant Science Laboratories, University of Reading, Whiteknights, RG6 2AS, Reading, U.K..
Planta
|January 14, 2014
Summary
Red light absorption by plant pigments reduces its effectiveness in controlling stem growth. Higher light intensities are needed for phytochrome control in green plants, impacting red light
Area of Science:
- Plant Physiology
- Photobiology
- Spectroscopy
Background:
- Phytochrome mediates plant photomorphogenesis, responding to red and far-red light.
- Photosynthetic pigments absorb light, potentially interfering with phytochrome signaling.
- Understanding light screening is crucial for controlling plant growth with specific wavelengths.
Purpose of the Study:
- To investigate the effect of red light absorption by photosynthetic pigments on phytochrome-controlled stem growth in Phaseolus vulgaris L. seedlings.
- To determine the optimal wavelength for phytochrome induction in green seedlings.
- To compare light requirements for phytochrome control between etiolated and green seedlings.
Main Methods:
- Exposure of Phaseolus vulgaris L. seedlings to different wavelengths and irradiances of red light.
- Measurement of stem growth and hypocotyl elongation.
- Assessment of phytochrome photoconversion (Pr to Pfr) under varying light conditions.
Main Results:
- Photosynthetic pigments significantly screen red light in stem tissues, with greater screening in the first internode than the hypocotyl.
- The most effective wavelength for phytochrome induction of stem growth was found to be approximately 628 nm.
- Green seedlings require much higher irradiances for phytochrome control compared to etiolated seedlings, and the efficiency of 660 nm light is reduced.
Conclusions:
- Red light screening by photosynthetic pigments necessitates higher light intensities for effective phytochrome-mediated growth control in green plants.
- The optimal wavelength for phytochrome induction is shifted from the typical 660 nm due to pigment absorption.
- Reduced efficiency of 660 nm light highlights the importance of considering pigment screening in photomorphogenesis research.
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