Poster: Oxidative stress
Abs #
79: Cytosolic ascorbate peroxidase is essential for cell protection during oxidative stress in Arabidopsis
Reactive oxygen species (ROS) regulate many different processes in cells ranging from development to responses to biotic or abiotic stresses. Recent studies identified specific transcription factors that are elevated in cells in response to different forms of ROS-induced stress. However, little is known about the ROS signal transduction network that controls ROS metabolism in plants. To dissect and study the ROS-signal transduction network of plants we are using knockout plants deficient in key ROS-scavenging enzymes. Cytosolic ascorbate peroxidase 1 (Apx1) is a key hydrogen peroxide-removal enzyme in plants. Microarray analysis of knockout Apx1 Arabidopsis plants revealed that the expression of two zinc-finger proteins, Zat12 and Zat7, and a WRKY25 transcription factor was elevated in cells in response to oxidative stress. Microarray analysis of transgenic plants expressing Zat12 and analysis of Zat12 knockout plants suggest that Zat12 is an important component of the oxidative stress-response signal transduction network of Arabidopsis, required for Zat7, WRKY25 and Apx1 expression during oxidative stress. Protein oxidation assays in knockout APX1 plants revealed significant oxidative damage to Rubisco protein and other proteins. This finding provides evidence that cytosolic APX1 is involved in protection of the chloroplast from oxidative stress. To identify regulatory transcripts involved in the ROS signal transduction at early stages of oxidative stress we are performing time-course microarray analysis of knockout Apx1 plants in the presence or absence of oxidative stress.
