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Effect of Non-Chilling Temperature and Light Intensity during Growth of Squash Cotyledons on the Composition of Thylakoid Membrane Lipids and Fatty Acids

Xu, Yinong ; Siegenthaler, Paul-André

In: Plant and Cell Physiology, 1996, vol. 37, no. 4, p. 471-479

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    Title
    • Effect of Non-Chilling Temperature and Light Intensity during Growth of Squash Cotyledons on the Composition of Thylakoid Membrane Lipids and Fatty Acids
    Author
    • Xu, Yinong. Laboratoire de Physiologie végétale, Université de Neuchâtel, Rue Emile Agrand 13, CH-2007 Neuchâtel, Switzerland
    • Siegenthaler, Paul-André. Laboratoire de Physiologie végétale, Université de Neuchâtel, Rue Emile Agrand 13, CH-2007 Neuchâtel, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:299736
    Summary
    The lipid composition, in particular the content of fatty acids in phosphatidylglycerol (PG), is believed to be crucial for the understanding of the chilling injury mechanism occurring in the thylakoid membrane (TM) of higher plants. In this investigation, we have studied the effect of growth conditions (e.g. temperature and light) on the composition of glycerolipid classes and their respective fatty acids during the maturation period of squash cotyledons. We have found that the changes in the lipid fatty acid composition of TM which are induced by different temperature and light growth conditions occurred only during the development of cotyledons but not when these latter had reached their maturity. The major changes were an increase of 18:3 and a decrease of 16:0 in galacto- and sulfolipids, and an increase of 16:1(3t) and 18:3 with a concomitant decrease of 16:0 and 18:1 in PG, when the temperature was low (20°C compared to 30°C). We conclude that low temperature conditions of growth induced an increase of the end acyl products [18:3 and/or 16:1(3t)] in PG and galactolipids. The possible mechanism is discussed in terms of the relative temperature dependence of fatty acid synthesis and desaturation processes. The light intensity of growth affected only the fatty acid composition of PG, i.e. when it was high (350 compare to 100 μmol m−2 s−1), an increase of 16:1(3t) at the expense of 16:0 was observed. Whatever the growth conditions, the level of 16:1(3t) increased during the maturation of cotyledons and was characterized by an increasing linear correlation (r=0.99) with the fresh weight. In contrast, a decreasing linear relationship (r=-0.99) was found between the fresh weight and 16:0. Thus, we propose that a constant level of 16:1(3t) is a good criterion for defining the chloroplast maturity and that it is highly advisable to study the effect of temperature and light on the lipid composition when the cotyledons have reached their maturity. Under these conditions, these effects can be considered regardless of developmental factors