Reversal by light of deleterious effects of chilling on oxygen evolution, manganese and free fatty acid content in tomato thylakoids is not accompanied by restoration of the original membrane conformation |
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| Authors: | Maciej Garstka Zbigniew Kaniuga |
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| Institution: | Institute of Biochemistry, Univ. of Warsaw, Al. Zwirki i Wigury 93, PL-02-089 Warszaw, Poland;. |
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| Abstract: | Free fatty acids (FFA) generated in thylakoids upon chilling of tomato leaves at 0°C for a few days result in release of functionally active Mn and inactivation of O2 evolution. Chilling does not lead to a decrease in the extrinsic 16, 23 and 33 kDa polypeptides. Upon illumination of chilled leaves both Mn content and O2 evolution in thylakoids are restored and FFA content is reduced to the level of the control. Photoactivation of O2 evolution in chilled leaves does not change the ratio of unsaturated/saturated FFA. Constant Arrhenius activation energy (Ea) for O2 evolution by thylakoids isolated from control leaves was found, whereas it increased at temperatures below 8.0 and 10.5°C in thylakoids from cold-treated and photoactivated leaves, respectively. This indicates that restoration of O2 evolution as well as of FFA and Mn contents is not accompanied by a complete reversal of membrance conformation. |
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| Keywords: | Arrhenius plot chilling stress extrinsic peptide free fatty acid Lycopersicon esculentum manganese O2 evolution thylakoid membrance tomato |
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