Redox Control of Protein Tyrosine Phosphatases and Mitogen-Activated Protein Kinases in Plants

Environmental conditions, including light, temperature, water status, and soil salinity, all modify the redox state of plant cells (Allen et al., 1995). A number of studies have shown that oxidative stress is a common factor that affects plant growth and development under extreme environmental conditions (for review, see Mittler, 2002). Most recently, oxidative stress agent H2O2 has been shown to serve as a critical messenger molecule in many signal transduction pathways, including plant responses to pathogen, plant hormone abscisic acid, and abiotic stress factors (Wojtaszek, 1997; Pei et al., 2000; Bolwell et al., 2001; Mittler, 2002). At least one of the mechanisms underlying H2O2 function is the activation of calcium channels (Pei et al., 2000; Chico et al., 2002). Here, we report that plant Tyr phosphatases such as AtPTP1 (Xu et al., 1998) serve as targets for H2O2 and this may be associated with the regulation of mitogen-activated protein (MAP) kinase activity in plants.