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Light modulation of the gravitropic set-point angle (GSA)
1Department of Biology, University of York, PO Box 373, York YO1 5YW, UK. jd15@york.ac.uk
Journal of Experimental Botany
|January 25, 2002
Summary
Light influences plant growth direction by affecting the gravitropic set-point angle (GSA). Both photosynthesis and phytochrome play roles in mediating these light effects on GSA in plants like Tradescantia and tomato.
Area of Science:
- Plant Biology
- Photobiology
- Gravitropism
Background:
- The gravitropic set-point angle (GSA) determines plant organ orientation.
- Light is known to influence plant gravitropism, but the mechanisms are not fully understood.
Purpose of the Study:
- To investigate how light influences the GSA in Tradescantia nodes and tomato hypocotyls.
- To elucidate the roles of photosynthesis and phytochrome in mediating light's effects on GSA.
Main Methods:
- Experiments were conducted on light-grown Tradescantia and the lazy-2 mutant of tomato.
- Photon flux density of white light was varied.
- Photosynthetic inhibitors (DCMU) and other treatments (norflurazon) were applied.
Main Results:
- In Tradescantia, light-regulated developmental changes in GSA were observed, dependent on light intensity.
- The photosynthetic inhibitor DCMU abolished the light's effect on GSA in Tradescantia.
- Light-induced GSA reduction in lazy-2 tomato hypocotyls was sensitive to DCMU and norflurazon, indicating roles beyond just phytochrome.
Conclusions:
- Photosynthesis interacts with the GSA in Tradescantia.
- Light-mediated GSA changes in plant organs can be influenced by both phytochrome and photosynthesis.
- These findings offer new insights into the mechanisms of gravitropism.