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Photonastic Control of Leaflet Orientation in Melilotus indicus (Fabaceae)
A Schwartz1, S Gilboa, D Koller
1The Hebrew University of Jerusalem, Department of Agricultural Botany, Rehovot 76100, Israel.
Plant Physiology
|June 1, 1987
Summary
Melilotus indicus leaflet orientation is controlled by light (photonasty) and exhibits solar tracking (diaphototropism). The pulvinule perceives light, with differential sensitivity between leaf surfaces influencing movement.
Area of Science:
- Plant physiology
- Photobiology
- Plant movement
Background:
- Leaflet orientation in plants is crucial for photosynthesis and protection.
- Melilotus indicus exhibits complex light-driven movements.
Purpose of the Study:
- To investigate the solar-tracking capability of Melilotus indicus terminal leaflets.
- To understand the role of pulvinules in photonastic responses.
Main Methods:
- Studied detached leaves with excised lateral leaflets to focus on the terminal leaflet.
- Investigated light perception and response mechanisms in the pulvinule.
Main Results:
- Leaflet orientation is governed by photonastic and nyctinastic control, alongside diaphototropism.
- Pulvinules perceive photonastic excitation on both abaxial and adaxial surfaces.
- Differential light sensitivity and angle of incidence affect leaflet movement.
Conclusions:
- The pulvinule's structure and light-sensitive tissues dictate photonastic responses.
- Melilotus indicus demonstrates sophisticated light-tracking mechanisms for leaflet orientation.
