Molecular mechanisms of plant low temperature stress tolerance

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The survival of organisms subjected to freezing conditions depends on their ability to tolerate or alleviate stresses resulting from the freeze/thaw processes. The mechanisms involved in the acquisition of freezing tolerance ensure that damage is minimized at the cellular level. In cold-hardy plants such as wheat, low temperature exposure leads to the accumulation of hundreds of proteins, and many of them are therefore potentially associated with freezing tolerance. The current challenge is to identify which proteins have a specific role in tolerance, and how they function in cellular protection against freezing damage. These proteins are likely required in the cold acclimation process (pre-freezing in the fall) and/or in deacclimation and recovery (post-thaw in the spring). Efficient mechanisms are needed at both stages for optimal overwintering capacity of the plants. Protection against freezing-induced injuries is also needed for animal cells that are stored at ultra-low temperatures. Long-term storage of cells and tissues is needed for biotechnological applications such as drug toxicity testing and transplantation. This approach also requires the use of cryoprotective substances that protect cells and tissues from dehydration, changes in osmolarity and damage caused by ice formation during freezing. We have identified four wheat proteins (WCS120, TaIRI-2, TaENO and TaBAS1) that can efficiently protect liver and pancreas-derived cells during freezing, and another that remains to be characterized (TaCPN60). These proteins show different structural features and likely act as cryoprotectants via distinct mechanisms of action. The TaENO, TaBAS1 and TaCPN60 proteins have not been characterized in wheat. The long-term objective of my research program is to understand the cellular and molecular mechanisms that regulate freezing tolerance in plants. My short-term objectives for the next five years are to: 1- Determine if TaENO, TaBAS1 and TaCPN60 are associated with FT in wheat; 2- Determine the functions of TaENO and TaBAS1 in wheat; and 3- Identify novel ice-binding domains and engineer cryoactive proteins via protein design. The deliverables are fundamental and applied in scope: the identification of proteins associated with freezing tolerance in plants will provide tools for marker-assisted breeding, to facilitate the development of new genetic lines; and the identification of proteins/domains and generation of chimeric proteins with cryoprotective activity for mammalian cells. My multidisciplinary research program will provide training for 2 PhD, 2 MSc and 5-10 undergraduate students during the coming 5-year period, in an environment that complies with the equity, diversity and inclusion principles. The knowledge gained from my proposed research program will contribute to maintaining Canada's competitive edge in plant research and cell cryopreservation, and will benefit the Canadian plant agriculture and biotechnology sectors.