Collaborative Research: Defining Roles of Calcium Efflux Pumps in Modulating Calcium Signaling in Plants

About This Grant

This project investigates how plants use calcium signaling mechanisms to respond to changes in temperature, salt stress, and wounding. The long-term goal is to understand how plant cells sense and respond to stressful environments, and to use that knowledge to develop crop plants that are more productive. Projections indicate that worldwide food production must increase by more than 70% by the year 2050 to feed the expected increase in the human population. To accomplish this, there is a need to develop crops that are more tolerant to suboptimal agricultural lands and chaotic weather events. This research project seeks to better understand how plants use calcium as an intracellular signaling molecule, and may lead to new ways to improve high-temperature tolerance in plants. Calcium signals are initiated when cell membrane ion channels open and allow calcium to enter the cytoplasm of a cell. The transient signal ends after calcium efflux transporter molecules remove the calcium and restore normal resting calcium levels. The focus of the research is to understand how cells regulate normal resting levels of calcium, and whether long-term changes in those resting levels provide a mechanism to reprogram cells to adapt to different stresses or developmental situations. The project incorporates genetic tools to manipulate the resting levels of calcium and test for their importance during plant development and responses to the environment. Additionally, the project will provide an opportunity for teams of undergraduate students to gain a true research experience to help develop critical thinking skills relevant to science and technology oriented careers. It will also provide research training for graduate students at both institutions. Calcium ion signaling is a fundamental feature of eukaryotic cells, and is critical for plants and animals to respond to biotic and abiotic stress conditions. While most research in plants has focused on stimuli that trigger calcium ion influx into the cytoplasm at the start of a calcium signal, relatively little is known about how calcium efflux systems reset basal levels of cytosolic calcium, and what happens if those basal levels are reset to different starting points. The focus of this project is on the role of ATP-dependent calcium efflux pumps referred to as Autoinhibited Calcium ATPases (ACAs). The project uses genetic knockouts of different calcium efflux pumps in Arabidopsis to increase or decrease basal cytosolic calcium concentrations when mutant plants are grown on media with varying concentrations of external calcium. The central hypothesis being tested is that calcium pumps play a critical role in defining basal levels of cytosolic calcium concentration, and that stable changes in basal calcium concentration can manifest as global changes in cellular physiology, gene expression, and an organism’s response to developmental or environmental stimuli. The first aim is to identify changes in calcium dynamics resulting from increasing or decreasing the activity of calcium pumps. The second aim is to identify environmental conditions that reset basal calcium concentrations. To provide undergraduates with an authentic research experience, a CURE (Course-Based Research Experience) will be developed in which students may identify molecules that trigger calcium signals in plant roots. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.