The Effects Of Moderately High Temperature On Zeaxanthin Accumulation And Decay

Zhang, R; Kramer, D; Cruz, J; Struck, K; Sharkey, T

The Effects Of Moderately High Temperature On Zeaxanthin Accumulation And Decay

Zhang, R Kramer, D Cruz, J Struck, K Sharkey, T

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Publisher:: Springer
Publication Type:: Journal Article
Citation:: Photosynthesis Research, 2011, 108 (2-3), pp. 171 - 181
Issue Date:: 2011-01

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Field	Value	Language
dc.contributor.author	Zhang, R	en_US
dc.contributor.author	Kramer, D	en_US
dc.contributor.author	Cruz, J	en_US
dc.contributor.author	Struck, K	en_US
dc.contributor.author	Sharkey, T	en_US
dc.date.issued	2011-01	en_US
dc.identifier.citation	Photosynthesis Research, 2011, 108 (2-3), pp. 171 - 181	en_US
dc.identifier.issn	0166-8595	en_US
dc.identifier.uri	http://hdl.handle.net/10453/28870
dc.description.abstract	Moderately high temperature reduces photosynthetic capacities of leaves with large effects on thylakoid reactions of photosynthesis, including xanthophyll conversion in the lipid phase of the thylakoid membrane. In previous studies, we have found that leaf temperature of 40 degrees C increased zeaxanthin accumulation in dark-adapted, intact tobacco leaves following a brief illumination, but did not change the amount of zeaxanthin in light-adatped leaves. To investigate heat effects on zeaxanthin accumulation and decay, zeaxanthin level was monitored optically in dark-adapted, intact tobacco and Arabidopsis thaliana leaves at either 23 or 40 degrees C under 45-min illumination. Heated leaves had more zeaxanthin following 3-min light but had less or comparable amounts of zeaxanthin by the end of 45 min of illumination. Zeaxanthin accumulated faster at light initiation and decayed faster upon darkening in leaves at 40 degrees C than leaves at 23 degrees C, indicating that heat increased the activities of both violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZE). In addition, our optical measurement demonstrated in vivo that weak light enhances zeaxanthin decay relative to darkness in intact leaves of tobacco and Arabidopsis, confirming previous observations in isolated spinach chloroplasts. However, the maximum rate of decay is similar for weak light and darkness, and we used the maximum rate of decay following darkness as a measure of the rate of ZE during steady-state light. A simulation indicated that high temperature should cause a large shift in the pH dependence of the amount of zeaxanthin in leaves because of differential effects on VDE and ZE. This allows for the reduction in Delta pH caused by heat to be offset by increased VDE activity relative to ZE.	en_US
dc.publisher	Springer	en_US
dc.relation.ispartof	Photosynthesis Research	en_US
dc.relation.isbasedon	10.1007/s11120-011-9672-y	en_US
dc.subject.classification	Plant Biology & Botany	en_US
dc.title	The Effects Of Moderately High Temperature On Zeaxanthin Accumulation And Decay	en_US
dc.type	Journal Article
utslib.citation.volume	2-3	en_US
utslib.citation.volume	108	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	0604 Genetics	en_US
utslib.for	0601 Biochemistry and Cell Biology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	closed_access
pubs.consider-herdc	false	en_US
pubs.issue	2-3	en_US
pubs.volume	108	en_US

Abstract:

Moderately high temperature reduces photosynthetic capacities of leaves with large effects on thylakoid reactions of photosynthesis, including xanthophyll conversion in the lipid phase of the thylakoid membrane. In previous studies, we have found that leaf temperature of 40 degrees C increased zeaxanthin accumulation in dark-adapted, intact tobacco leaves following a brief illumination, but did not change the amount of zeaxanthin in light-adatped leaves. To investigate heat effects on zeaxanthin accumulation and decay, zeaxanthin level was monitored optically in dark-adapted, intact tobacco and Arabidopsis thaliana leaves at either 23 or 40 degrees C under 45-min illumination. Heated leaves had more zeaxanthin following 3-min light but had less or comparable amounts of zeaxanthin by the end of 45 min of illumination. Zeaxanthin accumulated faster at light initiation and decayed faster upon darkening in leaves at 40 degrees C than leaves at 23 degrees C, indicating that heat increased the activities of both violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZE). In addition, our optical measurement demonstrated in vivo that weak light enhances zeaxanthin decay relative to darkness in intact leaves of tobacco and Arabidopsis, confirming previous observations in isolated spinach chloroplasts. However, the maximum rate of decay is similar for weak light and darkness, and we used the maximum rate of decay following darkness as a measure of the rate of ZE during steady-state light. A simulation indicated that high temperature should cause a large shift in the pH dependence of the amount of zeaxanthin in leaves because of differential effects on VDE and ZE. This allows for the reduction in Delta pH caused by heat to be offset by increased VDE activity relative to ZE.

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http://hdl.handle.net/10453/28870