ROS-Induced Kinase

Abstract

Plants use the production of reactive oxygen species (ROS) in response to various types of stress and during development. Rentel et al. have identified a serine-threonine kinase whose activity and expression are induced by ROS and that they have named OXI1 for OXIDATIVE SIGNAL-INDUCIBLE 1. The expression of OXI1 was increased in Arabidopsis seedlings exposed to peroxide (the initial screening conditions), as well as in response to natural stimuli that promote ROS production, such as wounding, pathogenic invasion, or treatment with cellulase. In addition, OXI1 expression was seen in the root, which is consistent with the known role for ROS in root development. OXI1-deficient plants were more susceptible to pathogens and showed defective root development. The kinase activity of OXI1 was stimulated within 5 min by peroxide or cellulase, which indicates that stresses that produce ROS likely modulate enzymatic activity of OXI1 rather than synthesis of the enzyme. Peroxide and cellullase stimulation of the plant homologs of mitogen-activated protein kinases MPK3 and MPK6 was reduced in OXI1-deficient plants. M. C. Rentel, D. Lecourieux, F. Ouaked, S. L. Usher, L. Petersen, H. Okamoto, H. Knight, S. C. Peck, C. S. Grierson, H. Hirt, M. R. Knight, OXI1 kinase is necessary for oxidative burst-mediated signalling in Arabidopsis . Nature 427 , 858-861 (2004). [Online Journal]