Journal Article

Imaging of NPQ and ROS Formation in Tobacco Leaves: Heat Inactivation of the Water–Water Cycle Prevents Down-Regulation of PSII

Éva Hideg, Péter B. Kós and Ulrich Schreiber

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 12, pages 1879-1886
Published in print December 2008 | ISSN: 0032-0781
Published online December 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn170
Imaging of NPQ and ROS Formation in Tobacco Leaves: Heat Inactivation of the Water–Water Cycle Prevents Down-Regulation of PSII

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  • Biochemistry
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  • Plant Sciences and Forestry

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Non-photochemical chlorophyll fluorescence quenching (NPQ) plays a major role in the protection of the photosynthetic apparatus against damage by excess light, which is closely linked to the production of reactive oxygen species (ROS). The effect of a short heat treatment on NPQ and ROS production was studied with detached tobacco leaves by fluorescence imaging of chlorophyll and of the ROS sensor dye HO-1889NH. NPQ was stimulated >3-fold by 3 min pre-treatment at 44°C, in parallel with suppression of CO2 uptake, while no ROS formation could be detected. In contrast, after 3 min pre-treatment at 46°C, NPQ was suppressed and ROS formation was indicated by quenching of HO-1889NH fluorescence. After 3 min pre-treatment at 46°C and above, partial inactivation of ascorbate peroxidase and light-driven accumulation of H2O2 was also observed. These data are discussed as evidence for a decisive role of the Mehler ascorbate peroxidase or water–water cycle in the formation of the NPQ that reflects down-regulation of PSII.

Keywords: Fluorescence imaging; Heat stress-reactive oxygen species (ROS); Mehler ascorbate peroxidase (MAP) cycle; PAM fluorometry; Photosynthetic electron transport

Journal Article.  5343 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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