High-Temperature Induced Chlorophyll Fluorescence Rise in Plants at 40–50 °C: Experimental and Theoretical Approach
We studied the temperature dependence of chlorophyll fluorescence intensity in barley leaves under weak and actinic light excitation during linear heating from room temperature to 50 °C. The heat-induced fluorescence rise usually appearing at around 40-50 °C under weak light excitation was also foun...
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Published in | Photosynthesis research Vol. 81; no. 1; pp. 49 - 66 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Dordrecht
Springer Nature B.V
01.07.2004
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Subjects | |
Online Access | Get full text |
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Summary: | We studied the temperature dependence of chlorophyll fluorescence intensity in barley leaves under weak and actinic light excitation during linear heating from room temperature to 50 °C. The heat-induced fluorescence rise usually appearing at around 40-50 °C under weak light excitation was also found in leaves treated with 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) or hydroxylamine (NH^sub 2^OH). However, simultaneous treatment with both these compounds caused a disappearance of the fluorescence rise. We have suggested that the mechanism of the heat-induced fluorescence rise in DCMU-treated leaves is different than that in untreated or NH^sub 2^OH-treated leaves. In DCMU-treated leaves, the heat-induced fluorescence rise reflects an accumulation of Q^sub A^^sup -^ even under weak light excitation due to the thermal inhibition of the S^sub 2^Q^sub A^^sup -^ recombination as was further documented by a decrease in the intensity of the thermoluminescence Q band. Mathematical model simulating this experimental data also supports our interpretation. In the case of DCMU-untreated leaves, our model simulations suggest that the heat-induced fluorescence rise is caused by both the light-induced reduction of Q^sub A^ and enhanced back electron transfer from Q^sub B^ to Q^sub A^. The simulations also revealed the importance of other processes occurring during the heat-induced fluorescence rise, which are discussed with respect to experimental data.[PUBLICATION ABSTRACT] |
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ISSN: | 0166-8595 1573-5079 |
DOI: | 10.1023/B:PRES.0000028391.70533.eb |