期刊
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY
卷 104, 期 1-2, 页码 271-284出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jphotobiol.2011.01.003
关键词
Fluorescence lifetime imaging microscopy; Lutein; Lutein epoxide; Polar plot; Thermal energy dissipation; Xanthophyll cycle
资金
- Deutsche Akademische Austauschdienst (DAAD) (PPP-USA) [D/07/10566]
- Taiwan Merit Scholarships [TMS-094-1-A-036]
- Department of Plant Biology at the University of Illinois at Urbana-Champaign
- Research Board at UIUC
Lifetime-resolved imaging measurements of chlorophyll a fluorescence were made on leaves of avocado plants to study whether rapidly reversible Delta pH-dependent (transthylakoid H+ concentration gradient) thermal energy dissipation (qE) and slowly reversible Delta pH-independent fluorescence quenching (ql) are modulated by lutein-epoxide and violaxanthin cycles operating in parallel. Under normal conditions (without inhibitors), analysis of the chlorophyll a fluorescence lifetime data revealed two major lifetime pools (1.5 and 0.5 ns) for photosystem II during the Delta pH build-up under illumination. Formation of the 0.5-ns pool upon illumination was correlated with dark-retention of antheraxanthin and photo-converted lutein in leaves. Interconversion between the 1.5- and 0.5-ns lifetime pools took place during the slow part of the chlorophyll a fluorescence transient: first from 1.5 ns to 0.5 ns in the P-to-S phase, then back from 0.5 ns to 1.5 ns in the S-to-M phase. When linear electron transport and the resulting Delta pH build-up were inhibited by treatment with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), the major fluorescence intensity was due to a 2.2-ns lifetime pool with a minor faster contribution of approximately 0.7 ns. In the presence of DCMU, neither the intensity nor the lifetimes of fluorescence were affected by antheraxanthin and photo-converted lutein. Thus, we conclude that both antheraxanthin and photo-converted lutein are able to enhance Delta pH-dependent qE processes that are associated with the 0.5-ns lifetime pool. However, unlike zeaxanthin, retention of antheraxanthin and photo-converted lutein may not by itself stabilize quenching or cause ql. (C) 2011 Elsevier B.V. All rights reserved.
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