Document Type

Article

Publication Date

1-2005

Journal or Book Title

The Plant Cell

Volume

17

Issue

1

First Page

268

Last Page

281

DOI

10.​1105/​tpc.​104.​026971

Abstract

Reactive oxygen species (ROS), such as O2 and H2O2, play a key role in plant metabolism, cellular signaling, and defense. In leaf cells, the chloroplast is considered to be a focal point of ROS metabolism. It is a major producer of O2and H2O2 during photosynthesis, and it contains a large array of ROS-scavenging mechanisms that have been extensively studied. By contrast, the function of the cytosolic ROS-scavenging mechanisms of leaf cells is largely unknown. In this study, we demonstrate that in the absence of the cytosolic H2O2-scavenging enzyme ascorbate peroxidase 1 (APX1), the entire chloroplastic H2O2-scavenging system of Arabidopsis thaliana collapses, H2O2 levels increase, and protein oxidation occurs. We further identify specific proteins oxidized in APX1-deficient plants and characterize the signaling events that ensue in knockout-Apx1 plants in response to a moderate level of light stress. Using a dominant-negative approach, we demonstrate that heat shock transcription factors play a central role in the early sensing of H2O2 stress in plants. Using knockout plants for the NADPH oxidase D protein (knockout-RbohD), we demonstrate that RbohD might be required for ROS signal amplification during light stress. Our study points to a key role for the cytosol in protecting the chloroplast during light stress and provides evidence for cross-compartment protection of thylakoid and stromal/mitochondrial APXs by cytosolic APX1.

Comments

This article is from The Plant Cell 17, no. 1 (January 2005): 268–281, doi:10.1105/tpc.104.026971.

Copyright Owner

American Society of Plant Biologists

Language

en

File Format

application/pdf

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