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Lily pistils bend toward light.
Masamichi Yamashita1, Minobu Shimizu, Satoshi Yamashita
1Institute of Space and Astronautical Science/JAXA.
Uchu Seibutsu Kagaku
|April 29, 2005
Summary
Lily pistils bend upward using only light cues, not gravity. This phototropism is linked to changes in pistil elongation rates after the flower opens.
Area of Science:
- Plant biology
- Phototropism
- Plant development
Background:
- Flower shape and orientation are influenced by environmental factors.
- Gravitropism, mediated by amyloplasts, typically guides plant growth direction.
- The lily pistil (Lilium cv. 'Casablanca') exhibits upward bending, suggesting a different mechanism.
Purpose of the Study:
- To investigate the mechanism behind the upward bending of the lily pistil.
- To determine the role of light (phototropism) versus gravity (gravitropism) in pistil orientation.
- To understand the relationship between pistil elongation and bending.
Main Methods:
- Observation of pistil morphology and amyloplast presence in lily flowers.
- Analysis of pistil elongation rates and bending patterns.
- Spot irradiation experiments to identify light-sensing regions.
Main Results:
- Absence of sediment amyloplasts in the lily pistil indicates no gravitropism.
- Pistil bending occurs post-flowering, coinciding with amyloplast disappearance (except in guard cells).
- Phototropism drives bending as local elongation rates peak and decline, with bending following basal elongation.
Conclusions:
- The lily pistil's upward bending is exclusively mediated by phototropism.
- Light perception and bending sites are closely located.
- Pistil development and orientation are dynamically regulated by light and elongation dynamics.