Identification of Plant Genes that Confer Enhanced Capacity to Tolerate Oxidative Stress

Plants cope with adverse environmental conditions by inducing systems that function to ameliorate the excess oxidative stress that occurs as a consequence. Much is now known concerning the primary anti oxidative mechanisms that exist in plants but the contribution of different genes involved, how the various oxidative stress-tolerant mechanisms are regulated and how the different systems are signaled remains less clear. We have developed a genetic screening strategy that provides for an efficient means to identify mutant lines of Arabidopsis that possess enhanced tolerance to oxidative stress. In subjecting a mutant population to this functional screen, we have isolated at least six lines (designated ost, for Qxidative §.tress tolerant) displaying different degrees oftolerance to oxidative stress. Several of these lines are tagged with the activation-tagging T-DNA used to generate the mutant population. One line, ost2.1, shows striking resistance to the oxidative stress conditions employed in the screen and displays cross40lerance as improved growth and survival under a broad range of conditions that cause oxidative stress. The specific aims of this proposal are to identify additional mutant lines from a recently acquired, larger activation-tagged mutant population with the stress-tolerant primary and secondary screens to identify key genes that govern oxidative stress tolerance. The other aims are to characterize the ost2.1 mutant line and clone its gene as well as to characterize ost5.1, ost8.3, ost 10.1 and isolate the tagged genes in these lines. We also aim to further characterize the enhanced stress tolerance of currently isolated Arabidopsis mutant lines as well as new stress-tolerant lines to increase understanding of the regulation and limits of plant stress tolerance mechanisms.