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Evaluation of Photosynthetic Behaviors by Simultaneous Measurements of Leaf Reflectance and Chlorophyll Fluorescence Analyses
Published on: August 9, 2019
Relationship between Photoconvertible and Nonphotoconvertible Protochlorophyllides
1Department of Biology, Brandeis University, Waltham, Massachusetts 02154.
Plant Physiology
|October 1, 1971
Summary
Bean leaves contain two protochlorophyllide forms. Protochlorophyllide(632) may convert to protochlorophyllide(650), which is directly photoconvertible to chlorophyllide, impacting plant greening.
Area of Science:
- Plant biochemistry
- Photosynthesis research
- Photobiology
Background:
- Protochlorophyllide is a key pigment in chlorophyll biosynthesis.
- Two distinct forms of protochlorophyllide exist in etiolated plants.
- Understanding these forms is crucial for elucidating chlorophyll synthesis pathways.
Purpose of the Study:
- To investigate the distinct roles and interconversion of protochlorophyllide forms in Phaseolus vulgaris.
- To explore the regulatory mechanisms of chlorophyll synthesis under various conditions.
Main Methods:
- Differential extraction and sucrose density gradient centrifugation to separate protochlorophyllide forms.
- Treatment with delta-aminolevulinic acid and cycloheximide to study pigment accumulation and greening inhibition.
- Exposure to nitrogen atmosphere to block chlorophyll synthesis.
Main Results:
- Two protochlorophyllide forms, photoconvertible protochlorophyllide(650) and non-photoconvertible protochlorophyllide(632), were identified.
- Protochlorophyllide(632) accumulates upon delta-aminolevulinic acid feeding and may be a precursor to protochlorophyllide(650).
- Nitrogen atmosphere inhibits chlorophyll synthesis, but a protochlorophyllide(632) stockpile can support limited greening.
Conclusions:
- Protochlorophyllide(632) likely serves as a precursor to protochlorophyllide(650), highlighting a novel regulatory step in chlorophyll biosynthesis.
- Cycloheximide-sensitive processes are involved in the light-dependent regeneration of protochlorophyllide(650).
- The findings provide insights into the dynamic interconversion of protochlorophyllide pigments and their role in plant photomorphogenesis.
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