A grant has been awarded to Dr. Raymond Zielinski of the University of Illinois to elucidate mechanisms regulating the function of stomatal guard cells by calcium.. His study will employ a combination of molecular, cellular and genetic approaches to visualize the activity of regulatory molecules that control stomatal function in living cells. Changes in the concentration of calcium ions are an early, important signal in regulating stomatal closure and restricting water loss from leaves. However, little is known about the mechanisms by which calcium signals are communicated to facilitate stomatal closure. The primary hypothesis driving this research is that the information in calcium signals required for stomatal closure is transduced by characteristic changes in the activation and distribution of the calcium receptor protein calmodulin. To test this hypothesis, he will measure changes in calmodulin activation using novel fluorescent indicators expressed in transgenic plants that allow calmodulin activation to be visualized in live cells. His project will employ the model plant, Arabidopsis thaliana, to take advantage of the tremendous number of genetic resources facilitated by the genomic characterization and sequencing efforts.
Stomata are structures defined by pairs of guard cells that form pores on leaf surfaces, which open or close in response to the vast array of environmental conditions experienced by plants. Stomatal pores open to allow the entry of CO2 into leaves for photosynthesis while at the same time restricting water loss by evaporation that can lead to wilting and plant death. Balancing these conflicting activities plays a major role in determining plant growth in natural ecosystems and crop plant productivity in agriculture. Defining how stomatal guard cells regulate the critical balance between CO2 uptake and water loss is key to understanding the major determinant influencing agricultural yields and how it may be affected by global climate change.
