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Lipid biosynthesis in green leaves of developing maize
J C Hawke1, M G Rumsby, R M Leech
1Department of Biology, University of York, Heslington, York, YO1 5DD, England.
Plant Physiology
|April 1, 1974
Summary
Maize leaf sections show distinct fatty acid synthesis patterns. Younger leaf bases produce longer-chain fatty acids, while mature leaf tips synthesize more unsaturated fatty acids under higher light, impacting lipid composition.
Area of Science:
- Plant Physiology
- Biochemistry
- Lipid Metabolism
Background:
- Fatty acid biosynthesis in plants is crucial for membrane structure and function.
- Differentiation in plant tissues leads to variations in metabolic capabilities.
- Light intensity is a key environmental factor influencing plant metabolism.
Purpose of the Study:
- To investigate the divergent patterns of fatty acid biosynthesis in different maize leaf zones.
- To determine the influence of light intensity on fatty acid synthesis and composition.
- To analyze the incorporation of newly synthesized fatty acids into specific lipid classes.
Main Methods:
- Incubation of successive maize leaf sections (base to tip) with acetate-1-(14)C.
- Analysis of fatty acid composition and proportions of unsaturated fatty acids.
- Varying light intensities (150 ft-c and 2800 ft-c) and temperatures (30°C and 20°C) during incubation.
- Quantification of radioactive fatty acids in different lipid classes (monogalactolipid, phosphatidyl choline, phosphatidyl ethanolamine).
Main Results:
- Basal leaf regions (proplastids) synthesized limited unsaturated fatty acids but significant long-chain fatty acids (>20 carbons).
- Distal leaf sections (chloroplasts) showed increased unsaturated fatty acid synthesis (18:1, 18:2) with higher light intensity, with total synthesis increasing 4-fold.
- Newly synthesized fatty acids in mature tissue resembled endogenous fatty acids, with limited 18:3 synthesis from 18:1 and 18:2, impacting monogalactolipid composition.
- Phosphatidyl choline was the major acyl lipid synthesized; phosphatidyl glycerol and monogalactolipid synthesis were stimulated by high light in mature tissues.
Conclusions:
- Maize leaf development involves distinct spatial regulation of fatty acid biosynthesis.
- Light intensity significantly modulates the rate and type of fatty acid synthesis in mature leaf tissues.
- Differences in newly synthesized and endogenous fatty acid profiles are linked to the low biosynthesis rate of 18:3 from shorter-chain precursors.
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