Effects of polyamines on the functionality of photosynthetic membrane in vivo and in vitro |
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Authors: | Nikolaos E Ioannidis |
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Institution: | Department of Biology, University of Crete, P.O. Box 2208, GR-71409 Heraklion, Crete, Greece |
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Abstract: | The three major polyamines are normally found in chloroplasts of higher plants and are implicated in plant growth and stress response. We have recently shown that putrescine can increase light energy utilization through stimulation of photophosphorylation Ioannidis et al., (2006) BBA-Bioenergetics, 1757, 821-828]. We are now to compare the role of the three major polyamines in terms of chloroplast bioenergetics. There is a different mode of action between the diamine putrescine and the higher polyamines (spermidine and spermine). Putrescine is an efficient stimulator of ATP synthesis, better than spermidine and spermine in terms of maximal % stimulation. On the other hand, spermidine and spermine are efficient stimulators of non-photochemical quenching. Spermidine and spermine at high concentrations are efficient uncouplers of photophosphorylation. In addition, the higher the polycationic character of the amine being used, the higher was the effectiveness in PSII efficiency restoration, as well as stacking of low salt thylakoids. Spermine with 50 μM increase FV as efficiently as 100 μM of spermidine or 1000 μM of putrescine or 1000 μM of Mg2+. It is also demonstrated that the increase in FV derives mainly from the contribution of PSIIα centers. These results underline the importance of chloroplastic polyamines in the functionality of the photosynthetic membrane. |
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Keywords: | Chl chlorophyll DCMU 3-(3&prime 4&prime -dichlorophenyl)-1 1-dimethylurea PS photosystem Put Putrescine PAR photosynthetically active radiation PAs polyamines NPQ non-photochemical quenching FV/FM maximum photosynthetic efficiency FV = FM &minus F0 maximum variable fluorescence FM maximum fluorescence (dark) FM&prime maximum fluorescence (light) F0 initial fluorescence LEF linear electron flow Fecy Ferricyanide MV methylviologen Δψ electrical component of the proton motive force ATP adenosine triphosphate HEPES (N-2-Hydroxyethylpiperazine-N&prime -2-ethanesulfonic acid) Tricine (N-tris-(hydroxymethyl)methylglycine) |
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