1.  In vivo Genomics: Visualizing Heterotrimeric G protein Interactions in Arabidopsis

Heterotrimeric G proteins couple signals that bind membrane hormone receptors to downstream effectors such as enzymes and ion channels.  Thus these complexes are an important point for control of signal transduction.  While metazoan cells have hundreds of different heterotrimeric complexes and thousands of receptors making the study of these pathways in animal cells difficult, plant cells have essentially only one complex, thus an understanding of the transduction mechanisms is at reach with Arabidopsis.  This 2010 project focuses on a cell biological techniques called FRET (Fluorescence Resonance Energy Transfer) to "visualize" in vivo the coupling of receptors to effectors by the Arabidopsis G complex.

2.  Analysis of Two-Component Signaling in Arabidopsis

Two-component systems are the primary means by which bacteria sense and respond to environmental stimuli. These systems are comprised of a number of distinct elements, namely histidine kinases, response regulators and in the case of phosphorelays, histidine phosphotransfer proteins (HPts). Genetic and molecular studies in Arabidopsis have implicated two-component elements in hormone signaling, red-light perception, circadian rhythms and perhaps osmosensing. This site describes studies focused on these Arabidopsis two-component elements.

3. The Arabidopsis RPM1 Signaling Network: A paradigm for NBS-LRR mediated plant disease resistance.

This Arabidopsis 2010 proposal uses a multidisciplinary approach to determine the function for a network or group of genes. The network in question includes members of the Nucleotide Binding site-Leucine-Rich-Repeat (NB-LRR) class of disease resistance proteins and key regulators of their function. Experiments proposed will determine how NB-LRR proteins are assembled into signal competent form before infection, and how their action is triggered by proteins produced by plant pathogens. This proposal uses complementary biochemical and genetic tools that were generated in the PI’s lab to dissect the RPM1-dependent disease resistance network. But because the function of NB-LRR proteins is regulated by several common components, data to be generated in this research are also germane to the study of disease resistance in general. The proposal makes use of an expanding NB-LRR protein tool kit in several Aims. The study of NB-LRR proteins in Arabidopsis has led to the notion that part of their activity is guided toward monitoring the cellular integrity of other host cellular machines. This proposal focuses also one of those important cellular components, the RIN4 protein. RIN4 shares a small plant-specific domain of unknown function, called NOI, with several other Arabidopsis proteins. This plant-specific protein family will also be studied.

Overall yield losses to pathogens can be as high as 30%. A detailed view of the molecular control of disease resistance is emerging from a community focus on the application of Arabidopsis to important problems in plant pathology. The reference plant is useful for studies of nearly all classes of pathogens that are agronomically relevant. Hence, the broader impacts of the proposed research project are that the results will significantly inform translation to crop species. In fact, this has already begun with the cloning and utilization of orthologues from crops of relevant genes first identified in Arabidopsis. The use of genetics, molecular biology, biochemistry, and cell biology makes this project an excellent training ground for scientists from undergraduate to post-doctoral levels. Topics investigated in this research project are incorporated into a course taught by the PI on “Strategies of Host-Microbe Interactions”. The PI’s lab has actively sought to engage undergraduates in research projects and the PI is involved in public policy and public debates directly related to the topics of this proposal.