Guard Cell Signaling and Systems Biology

Two pairs of Arabidopsis guard cells.

Pairs of guard cells found in the shoot epidermis circumscribe and define microscopic pores called stomata. In response to a myriad of environmental signals, guard cells regulate stomatal aperture size by osmotically-driven swelling or shrinking. Light-stimulated stomatal opening is imperative for uptake of carbon dioxide from the atmosphere, which is the starting point for carbon fixation during photosynthesis. Conversely, during drought, the plant hormone abscisic acid (ABA) inhibits stomatal opening and promotes stomatal closure, thereby promoting plant water conservation. In our laboratory, we assess guard cell responses by direct visualization of stomatal apertures under the microscope, by electrophysiological assays that measure the ionic currents responsible for changes in guard cell osmotica, by omics approaches that determine how the transcriptome, proteome, and metabolome change in response to environmental signals, and by whole plant measurements of carbon dioxide uptake and water loss, assessed using gas exchange techniques.

Light-Induced Stomatal Opening Network Model (Sun et. al. 2014)

Current projects are focused on the roles of heterotrimeric G-proteins as regulators of ABA signaling in guard cells, on red light regulation of the guard cell metabolome (in collaboration with Prof. Sixue Chen (U. Florida), and on guard cell redox proteomics (in collaboration with Profs. Sixue Chen and Alice Harmon (U. Florida). We have recently described ABA regulation of the guard cell transcriptome (Wang et al., 2011), proteome (Zhao et al., 2008; 2010), and metabolome (Jin et al., 2013), and with Prof. Reka Albert, Penn State Dept. of Physics, we are applying dynamic modeling and other systems biology tools to synthesize information on light- and ABA-regulated guard cell signaling from our group and from the literature into models that are both accurate and predictive (Li et al., 2006; Assmann and Albert, 2009; Assmann,2010; Li et al., 2012; Sun et al., 2014).