Collaborative Research: Systemic Signailng Networks in Arabidopsis

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Stresses such as herbivore or pathogen attack can severely limit plant growth and development, for example, by reducing crop production and impacting food security around the World. Plants possess natural sensory systems that allow them to detect these stresses and then mount defenses against them. Defining how these response systems operate is therefore important in both understanding how plants survive and thrive in the natural world and how to effectively capitalize on these innate responses to improve the resilience of agriculture. Recent research has made key advances in characterizing these signaling systems within the plant, revealing that plants deploy an internal biochemical communication system that broadcasts stress information from its site of perception to the rest of the plant body. This information then triggers the production of defenses such as the accumulation of toxic chemicals, priming even the non-attacked parts of the plant for defense. This communication system operates quickly, spreading information throughout the plant over the course of minutes. Despite such a central role in coordinating each plant’s rapid stress responses, the cellular components that trigger this system and then transmit the stress signal throughout the plant remain poorly defined. This project will focus on characterizing the role of two major cellular messengers, the calcium ion and reactive oxygen species, in propagating these rapid stress signals. The investigation will also explore how amino acids released by the plant may act as initial triggers for this response. This work will train graduate students and postdoctoral fellows to help prepare them for their future careers in research and science. The project will also provide public education on plant stress responses and provide training to students in effective science communication.Recent studies have revealed a rapid systemic signaling system in plants mediated through Ca2+- and reactive oxygen species-dependent events. This research program seeks to extend our understanding of these processes to the levels of the channels and tissue architectures that support this signaling network. The Arabidopsis thaliana Glutamate-Like Receptor (GLR) channels and reactive oxygen species-producing NADPH oxidases have been linked to this rapid systemic propagation of Ca2+-based signals. Therefore, this study will focus on defining the role(s) of these proteins in systemic transmission of local wound, pathogen elicitor (flg22) and salt stresses. The specific aims are to: (1) compare the patterns of Ca2+ and ROS signaling that occur during the initiation and propagation of long-distance signals in response to these stimuli and define the spatial and temporal characteristics of the channels and ROS-related enzymes supporting these activities; and (2) explore how glutamate and other amino acid signals are involved in triggering these long-distance signals. These goals will be accomplished using a combination of bioreporter imaging and mutant and molecular analyses. This study will reveal new insight into the molecular machinery underlying rapid plant systemic signaling. The project will help define the spatial and temporal changes in calcium and reactive oxygen species that relay information about stresses throughout the plant. The research will also help define whether information about each stress is likely encoded in specific signaling dynamics.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.