The role of active oxygen species in plant signal transduction

Adequate responses to environmental changes are crucial for plant growth and survival. However, the molecular and biochemical mechanisms that orchestrate these responses are still poorly understood and the signaling networks involved remain elusive. A central role for active oxygen species (AOS) during biotic and abiotic stress responses is well-recognized, although under these situations AOS can either exacerbate damage or act as signal molecules that activate multiple defense responses. This duality can be obtained only when cellular levels of AOS are tightly controlled at both the production and consumption levels. This review focuses on the involvement of AOS in stress signal transduction in plants, guided by a summary of work performed in our laboratory on plants that are deficient in catalase activity. These plants not only reveal the importance of catalase in coping with environmental stresses, but also provide a powerful in planta model system to study the multiple roles of hydrogen peroxide during plant stress. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.