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Two distinct blue-light responses regulate epicotyl elongation in pea
1Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60680.
Plant Physiology
|February 1, 1990
Summary
Blue light suppresses epicotyl elongation in pea seedlings. This blue light response is independent of phytochrome and requires a specific developmental state induced by red light for higher fluence responses.
Area of Science:
- Plant biology
- Photomorphogenesis
- Physiology
Background:
- Blue light is known to influence plant growth and development.
- Pea seedlings (Pisum sativum L.) exhibit suppressed epicotyl elongation under blue light when grown in red light.
- The fluence-response curve for blue light suggests two distinct responses: suppression at lower fluences and alleviation at higher fluences.
Purpose of the Study:
- To investigate the nature of blue light-induced suppression of epicotyl elongation in pea seedlings.
- To determine if two separate blue light responses are involved.
- To elucidate the role of phytochrome and red light in mediating these blue light responses.
Main Methods:
- Pea seedlings were grown under dark conditions to isolate blue light responses.
- Seedlings were treated with varying fluences of blue light.
- Phytochrome's involvement was tested using far-red light pulses.
- The effect of red light pre-treatment on blue light response was examined.
Main Results:
- In dark-grown seedlings, only the low-fluence blue light response (suppression of elongation) was observed.
- The kinetics of suppression in dark-grown seedlings mirrored that of red-light-grown seedlings.
- Blue light-induced suppression was not mediated by phytochrome, as far-red light had no effect.
- Red light pre-treatment was necessary for high-fluence blue light to elicit a response, indicating a requirement for a specific developmental state.
Conclusions:
- The low-fluence blue light response, suppressing epicotyl elongation, is independent of phytochrome.
- A specific developmental state, induced by red light, is required for pea seedlings to respond to high-fluence blue light.
- Blue light photomorphogenesis in pea seedlings involves complex interactions with light quality and developmental stage.
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