Intellectual Merit: Cellular calcium mediates diverse processes in both animal and plant cells, including gene expression, cell proliferation, cell division, metabolism, and cell movement. Stomata are microscopic pores each formed by a pair of guard cells that shrink and swell to regulate respiration. Calcium channels in the plasma membrane of these specialized cells play a crucial role in allowing an increase of cytosolic Ca2+, which causes these pores to close thus limiting water loss by the plant. Patterns of cytosolic Ca2+ dynamics encode information that impacts stomatal behavior and controls the specificity and efficiency of gene expression; however, the molecular identity of these Ca2+ channels in plants remains elusive. In addition, molecular mechanisms by which these Ca2+ patterns regulate cellular responses, including gene expression, have yet to be identified. Using Arabidopsis guard cells as a model system, the aim of this project is to investigate how a cellular Ca2+ signal is transduced by molecular components at the single-cell level. In this project, a multidisciplinary approach that includes computational modeling and molecular genetic analysis, will be used to characterize a family of putative Ca2+-permeable channel proteins in the plasma membrane and to analyze how cytosolic Ca2+ dynamics modulates gene expression in guard cells and contributes to the regulation of stomatal behavior. The results of this research will reveal novel molecular components of cellular Ca2+ signaling and provide new insights into Ca2+ dynamics-controlled cellular responses in plants.
Broader Impacts: Fresh water scarcity is one of the major global problems this century, and 65% of global fresh water is used for agriculture. Plants lose over 95% of their water via transpiration through stomatal pores in the leaf surface. Since cellular calcium plays a key role in the regulation of stomatal behavior, results and knowledge arising from the proposed research will contribute to protecting the environment and to improving agricultural productivity. Two postdoctoral fellows, two graduate students and one or more undergraduate students will participate in this project. The PI and co-PI will provide extensive mentoring to prepare postdoctoral associates for their future careers. The PI and co-PI will continue making a commitment to broadening the participation of students from underrepresented groups. The PI and co-PI will give presentations and lectures to the public to stimulate general interest in science and science education. In collaboration with colleagues, the PI plans to offer an open house to local and state governmental officials to provide a non-technical explanation of our research and give these policymakers an opportunity to see first hand tax dollars at work.
