Molecular mechanisms of oxidative stress tolerance in plants

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Each year Canada loses hundreds of millions of dollars from loss in crop productivity caused by different environmental stresses. Oxidative stress is a common response to different stresses such as heat, cold, high-light, drought, osmotic shock, wounding, UV-B radiation, ozone, aluminum and pathogens. Our studies on aluminum stress and tolerance allowed us to identify several genes that could play an important role in regulating plant responses to oxidative stress. Improving tolerance to this stress will likely enhance plant fitness by increasing cross-tolerance to a variety of stresses. To achieve this goal, we will: I) Characterize the regulatory factors involved in oxidative stress responses and their potential function in improving tolerance to reactive oxygen species (ROS). We have recently identified two Zinc finger transcription factor family members which expression is significantly associated with Al tolerance in near-isogenic wheat lines. These transcription factors are also responsive to different sources of oxidative stress such as H2O2 and hydroxyl radicals. Characterization of these wheat transcription factors and their upstream factors will help to understand their mechanisms of regulation. Over-expression of these factors in transgenic lines will confirm whether they can improve tolerance to aluminum and other ROS in either roots or leaves. II) Determine the function of key energy pathway regulatory genes involved in ROS detoxification. Among these genes, some encode enzymes (e.g. fructose-1,6-bisphosphatase and glucose-6-phosphate dehydrogenase) involved in the regulation of key energy pathways involved in the regeneration of antioxidant molecules. The effect of regulating these genes will be studied using transgenic plant models to evaluate their ability to produce antioxidant molecules and to tolerate oxidative stress. Understanding the regulatory mechanisms involved in oxidative stress tolerance will lead to the development of appropriate strategies for crop improvement allowing plants to withstand a variety of stresses. This will result in improved plant fitness and productivity.