期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 64, 期 6, 页码 1649-1661出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/ert024
关键词
Antheraxanthin; light transitions kinetics with seconds time resolution; non-photochemical quenching; photoprotection; Quercus coccifera; rapidly reversible photoprotective energy dissipation; zeaxanthin
资金
- Spanish Ministry of Science and Innovation [SUM2008-00004-C03-03, AGL2010-21153-CO2-02]
- Gobierno de Aragon [A03, A54]
- 'Juan de la Cierva' Spanish Ministry of Science and Innovation
Under excess light, the efficient PSII light-harvesting antenna is switched into a photoprotected state in which potentially harmful absorbed energy is thermally dissipated. Changes occur rapidly and reversibly, enhanced by de-epoxidation of violaxanthin (V) to zeaxanthin (Z). This process is usually measured as non-photochemical quenching (NPQ) of chlorophyll (Chl) fluorescence. Using instrumentation for instantaneous leaf freezing, NPQ, spectral reflectance, and interconversions within the xanthophyll cycle with time resolution of seconds were recorded from Quercus coccifera leaves during low light (LL) to high light (HL) transitions, followed by relaxation at LL. During the first 30 s of both the LL to HL and HL to LL transitions, no activity of the xanthophyll cycle was detected, whereas 7075% of the NPQ was formed and relaxed, respectively, by that time, the latter being traits of a rapidly reversible photoprotective energy dissipation. Three different Z pools were identified, which play different roles in energy dissipation and photoprotection. In conclusion, pH was crucial to NPQ formation and relaxation in Q. coccifera during light transitions. Only a minor fraction of Z was associated to quenching, whereas the largest Z pool was not related to thermal dissipation. The latter is proposed to participate in photoprotection acting as antioxidant.
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