Plants respond to the environment by utilizing a number of preformed and inducible signaling processes; interestingly, many of these responses share a number of common features. For example, plants respond to stresses imposed by limitations in water availability and pathogen infection by closing stomata- specialized pores on the leaf surface that not only function in gas exchange, but also are primary points of entry to many pathogens. Thus, in closing stomata plants restrict water loss as well as entry to potentially pathogenic microorganisms. Much in the same way that hormones regulate human cellular processes, plant hormones have been demonstrated to control plant response to changes in the environment, including the above noted response to environmental and pathogenic stressors. The long range goal of this project is to define how plant stress signals are regulated and transduced to elicit the plant immune response. To do this, the current work will use the plant stomata as a tractable marker to understand how chemical changes in a cell are perceived and ultimately transduced to regulate physical and mechanical changes in cellular movement, architecture, and shape. With this knowledge, the investigators will define the principle components that plants use to monitor their environments for potential threats, and moreover, to rapidly respond to these changes. The ultimate goal of this research is to uncover mechanisms that plants use to survive, and through dissemination of the Broader Impacts, to communicate these data to society to educate general public in the area of food production and security.
Actin is well known for its roles in defining cell shape and powering movement of organelles and macromolecules in all eukaryotic organisms. Additionally, as a component of the immune system of both plants and animals, the actin cytoskeleton has been demonstrated to respond to a variety of pathogen-derived elicitors. However, the mechanism(s) underpinning the role of actin in plant immunity is lacking. This study will leverage recently developed methods and resources in the PIs' laboratories to define, using the stomatal guard cell as an experimental paradigm and a series of quantitative cell biology and genetic approaches, the contribution and role of actin as a key component of the plant immune network. Plant stomatal guard cells are an attractive, amenable, and biologically relevant cell type for further dissecting the role of actin dynamics in plant immunity. The work described herein will define the relationships that link basic physiological processes (e.g., hormone signaling, pathogen perception) to the host immune response. Anticipated impacts of this project are: 1) the elucidation of the processes that dynamically respond to and function as cellular switches between, pathogen, immunity, and hormone signaling; 2) the phospho-regulation and pathogen targeting of a key plant regulatory node that controls cytoskeletal organization and stomatal guard cell dynamics; and 3) a demonstration of a role for actin in critical stomatal-based signaling pathways.
