Related Experiment Videos
Possible control of maize leaf sucrose-phosphate synthase activity by light modulation.
1United States Department of Agriculture/Agricultural Research Service, Beltsville, Maryland 20705.
Plant Physiology
|November 1, 1985
Summary
Light significantly increases sucrose phosphate synthase (SPS) activity in maize leaves, suggesting light modulation of sucrose production. Soybean SPS shows a smaller response, indicating species-specific light regulation.
Area of Science:
- Plant Physiology
- Biochemistry
- Photosynthesis Research
Background:
- Sucrose phosphate synthase (SPS) is a key enzyme in sucrose biosynthesis.
- Understanding light's role in regulating SPS is crucial for comprehending photosynthetic carbon partitioning.
Purpose of the Study:
- To investigate the diurnal and light-dependent regulation of SPS activity in maize and soybean.
- To determine if light influences SPS activity and substrate affinities.
Main Methods:
- Enzyme activity assays on leaf extracts from maize and soybean over a day/night cycle.
- Comparison of SPS activity in light- vs. dark-adapted leaves.
- Determination of substrate affinities (Km and K0.5) for partially purified SPS.
Main Results:
- Maize SPS activity showed a 2-3 fold increase post-illumination, correlating with light/dark transitions.
- Soybean SPS activity increased by only 30% under light conditions.
- Light-modulated changes in SPS activity were stable through chromatography.
- Altered substrate affinities were observed in light-acclimated maize SPS.
Conclusions:
- Light plays a significant role in modulating SPS activity in maize, impacting sucrose production.
- Species-specific differences exist in light regulation of SPS between maize and soybean.
- Light-induced changes in SPS activity are a key regulatory mechanism in sucrose synthesis.