Journal Article

Two Distinct Redox Signaling Pathways for Cytosolic APX Induction under Photooxidative Stress

Yukinori Yabuta, Takanori Maruta, Kazuya Yoshimura, Takahiro Ishikawa and Shigeru Shigeoka

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 11, pages 1586-1594
Published in print November 2004 | ISSN: 0032-0781
Published online November 2004 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pch181
Two Distinct Redox Signaling Pathways for Cytosolic APX Induction under Photooxidative Stress

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The cross-talk of two redox factors, H2O2 accumulation and redox status of photosynthetic electron transport (PET) in tobacco chloroplasts, on the expression of cytosolic ascorbate peroxidase (cAPX) was studied. Transgenic tobacco plants, which expressed respectively the Escherichia coli catalase and spinach thylakoid-membrane-bound APX in chloroplasts and showed increased tolerance to photooxidative stress, were used for evaluation of the relationship between H2O2 accumulation or change of redox status of PET and cAPX induction under photooxidative stress condition. There was no difference in the increase in the transcript level of cAPX in the first 1 h after irradiation with high-intensity light between the wild-type and either of the transgenic plants. The transcript level of cAPX in the wild-type showed a steady gradual increase during the next 5 h, while that in the transgenic plants during this period was stable. The H2O2 level of wild-type plants increased after 1 h, while those of transgenic plants remained constant. The decrease in qp value in all types of plants occurred earlier than the increase in H2O2 level. These results indicate that the induction of cAPX expression is caused by a redox change in PET, probably through the plastquinone pool at an early stage and thereafter by an increase in the cellular H2O2 level.

Keywords: Keywords: Ascorbate peroxidase (EC 1.11.1.11) — H2O2 — Photosynthetic electron transport — Signal transduction.; Abbreviations: AOS, active oxygen species; APX, ascorbate peroxidase [chlAPX, chloroplastic (stromal and thylakoid-membrane-bound) APX; cAPX, cytosolic APX; tAPX, thylakoid-membrane-bound APX]; 3-AT, 3-aminotriazole; DBMIB, 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone; MV, methyl viologen; PET, photosynthetic electron transport; SSC, standard saline citrate.

Journal Article.  6000 words.  Illustrated.

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

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