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Photosynthetic Electron Transport Regulates the Expression of Cytosolic Ascorbate Peroxidase Genes in Arabidopsis during Excess Light Stress

Stanislaw Karpinski, Carolina Escobar, Barbara Karpinska, Gary Creissen and Philip M. Mullineaux
The Plant Cell
Vol. 9, No. 4 (Apr., 1997), pp. 627-640
DOI: 10.2307/3870512
Stable URL: http://www.jstor.org/stable/3870512
Page Count: 14
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Photosynthetic Electron Transport Regulates the Expression of Cytosolic Ascorbate Peroxidase Genes in Arabidopsis during Excess Light Stress
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Abstract

Exposure of Arabidopsis plants that were maintained under low light (200 μmol of photons ${\rm m}^{-2}\ {\rm sec}^{-1}$) to excess light (200 μmol of photons ${\rm m}^{-2}\ {\rm sec}^{-1}$) for 1 hr caused reversible photoinhibition of photosynthesis. Measurements of photosynthetic parameters and the use of electron transport inhibitors indicated that a novel signal transduction pathway was initiated at plastoquinone and regulated, at least in part, by the redox status of the plastoquinone pool. This signal, which preceded the photooxidative burst of hydrogen peroxide ( H2 O2) associated with photoinhibition of photosynthesis, resulted in a rapid increase (within 15 min) in mRNA levels of two cytosolic ascorbate peroxidase genes (APX1 and APX2). Treatment of leaves with exogenous reduced glutathione abolished this signal, suggesting that glutathione or the redox status of the glutathione pool has a regulatory impact on this signaling pathway. During recovery from photoxidative stress, transcripts for cytosolic glutathione reductase (GOR2) increased, emphasizing the role of glutathione in this stress.

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