Effects of water stress on lipid metabolism in cotton leaves |
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Authors: | Claire Borrel-Flood Jorge Vieira da Silva Anne Marie Justin Paul Mazliak |
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Affiliation: | 1. Laboratoire d''Ecologie Générale et Appliquée, Université de Paris VII, 2 Place Jussieu, 75221 Paris Cedex 05, France;2. Laboratoire de Physiologie Cellulaire, Université Pierre et Marie Curie, 4 Place Jussieu, 75230 Cedex 05, France |
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Abstract: | After 2, 10 and 24 hr labelling with [1-14C] acetate, radioactivity incorporated into the lipids of cotton leaves is mainly found in phosphatidylcholine, phosphatidylglycerol and neutral lipids. Galactolipids are slowly synthesized and after 24 hr, account for only 10% of the total radioactivity. Under water stress, a marked decrease of precursor incorporation into leaf lipids occurs, particularly in phosphatidylcholine and galactolipids. Relative incorporation into neutral lipids, on the contrary, increases. Water deficits provoke an inhibition of the fatty acid desaturation, resulting in a sharp decrease of linoleic and linolenic acid biosynthesis. The decrease in unsaturated fatty acid biosynthesis occurs in all lipid classes, but is most pronounced in the galactolipid fractions. In the drought-resistant cotton variety (Mocosinho), the variations in lipid and fatty acid metabolism under water stress are less pronounced than in the drought-sensitive variety (Reba), and this attests a greater stability of the membrane system. |
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Keywords: | Malvaceae biosynthesis lipids, fatty acids drought. DGDG: digalactosyl-diacylglycerol MGDG: monogalactosyl-diacylglycerol NL: neutral lipids PC: phosphatidylcholine PG: phosphatidylglycerol PE: phosphatidylethanol-amine PI: phosphatidylinositol. |
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