The individual and network functions of cell surface receptors in plant stress responses

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One of the central goals of plant breeding is to produce disease-resistant crops without decreasing yield. A complete understanding of how plants regulate immunity and growth would allow for rationalization of this process. The long-term objective of my research program is to understand how plants use cell surface receptors to measure the environment and regulate energy expenditures to immunity and growth. Plants cannot move in order to avoid pathogenic attack or in search of improved environmental conditions. Instead, they have evolved to measure many aspects of their locale, including nutritional availability, environmental conditions, and pathogen presence. These disparate data streams are then integrated to appropriately guide energy expenditure to maximize survival and growth. Receptors belonging to the expanded leucine-rich repeat receptor kinase family (LRR-RKs) are known to play important roles in immunity and growth. While there is great interest in these proteins, most of the 225 LRR-RKs in the model plant Arabidopsis thaliana remain orphan receptors with no assigned function. ******This lack of knowledge presents an obvious obstacle to understanding how these receptors integrate information and regulate immunity and growth. The few characterized LRR-RKs are known to act as either direct ligand receptors, or to modulate signals in trans through physical interaction with the ligand receptors. We hypothesize that plants control immunity and growth through a signaling network governed by the formation of signaling-competent complexes via physical interactions between LRR-RKs.******To address this hypothesis and determine how this receptor network has evolved to function, we must first identify the biological function of the orphan LRR-RKs and then determine how these functions are integrated in the network. ******We will accomplish this by:*** Using several existing large datasets to predict novel biological function for orphan receptors.*** Experimentally validating these predictions and assigning biological function to orphan LRR-RKs and sub-networks.*** Mapping evolutionary data onto the network structure and combining that with functional information to understand how receptors and networks evolve and respond to stress.******Significance:***Fundamental biological processes such as immunity and growth are controlled by complex signaling networks rather than linear means. We now have approaches and datasets that allow us to interrogate these networks at a systems level and determine how these processes are controlled. An improved understanding of the underlying logic of these networks will allow designer production of improved crops through network manipulation. Our research program will also offer numerous training opportunities for HQP in laboratory and computational science, which will provide excellent preparation for a range of research fields and career paths.**