Molecular mechanisms of oxidative stress tolerance in plants

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In plants, 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. Together, these stresses cause major losses to several crops in Canada. We identified a subfamily of wheat transcription factors (TF) containing at least 53 members (named TaZFPs) that could play an important role in regulating plant responses to oxidative stress. Our results showed that most (52/53) members of this family are up-regulated by different abiotic stresses and two of them are associated to Al tolerance. In other species such as rice and Arabidopsis, the overexpression of specific members of this gene subfamily was shown to improve tolerance to oxidative stress and other abiotic stresses such as salt and drought stresses. However, the most important members of this gene subfamily remain to be identified in wheat.******Our long term goal is to develop efficient strategies to improve tolerance to oxidative stress, a major component of various abiotic and biotic stresses. Our working hypothesis is that specific wheat members of the TaZFP subfamily can improve tolerance to oxidative stress and enhance cross-tolerance to a variety of other stresses.******Our first short term objective is to “determine the function of selected TaZFP family members that are associated to oxidative stress” by function studies in wheat. We have recently demonstrated that the Barley Stripe Mosaic Virus (BSMV) can be used to rapidly and uniformly overexpress small genes. We will characterize the two TaZFPs associated to Al tolerance and initiate the characterization of TaZFPs genes that are strongly up-regulated by different abiotic stresses using the improved BSMV protocol. This approach avoids the need to produce transgenic plants and allows a rapid asessment of their ability to increase tolerance to Al and other abiotic stresses.******Our second objective is to “identify upstream transcription factors (TF) that regulate TaZFPs”. The promoters of the most important TaZFPs as determined in our first objective will be used to isolate upstream TFs using one-hybrid screening in yeast. These factors may regulate more than one TaZFPs and provide more efficient strategies to improve oxidative stress tolerance.******Our third objective is to “determine the function of selected miRNAs in Al/oxidative stress tolerance”. We have identified several miRNAs that are associated to Al tolerance and can target genes of potential interest for oxidative stress tolerance. We will validate the ability of these miRNAs to affect the expression of the predicted targets in vivo and to improve stress tolerance by using the BSMV system.******Overall, this knowledge will help design appropriate molecular markers to improve tolerance to different abiotic stresses. This will help support breeders in producing wheat varieties with improved productivity under adverse conditions.*****