Dissection of subcellular sites of NLR function during immune signaling

University Of California-Davis, Davis CA

Investigators

Abstract

Resistance proteins (R-proteins) are key players in a plant's defensive repertoire against pathogenic microbes. R-proteins act as sentinels that recognize incursion by a pathogen and initiate responses to limit the extent of infection. Although we understand in some detail the nature of the initial recognition event, little is known about how R-proteins signal to the plant that defenses need to be deployed. This project follows the intriguing observation that at least some R-proteins, once activated by a pathogen, interact with other proteins to stimulate enhanced expression of genes required to mount an effective immune response. The research to be carried out seeks to enhance our understanding of the molecular mechanisms that mediate these events. The results are likely to contribute new strategies for developing crop varieties that are resistant to economically significant plant diseases. The project will provide training for a postdoctoral researcher and a graduate student. Undergraduate students from under-represented minorities and economically disadvantaged students from the Biology Undergraduate Scholars Program (BUSP) will be trained. The project will also teach and train a high school student from Young Scholar Program (YSP) at UC Davis. The project will organize a science field trip for 5th grade students from an Elementary School to UC Davis. In plants and animals, the Nucleotide-binding domain and Leucine-rich Repeat (NLR) class of intracellular immune receptors function in defense against pathogens. Despite extensive research, post-pathogen recognition events leading to NLR activation and induction of defense signaling remain elusive. The investigators recent results indicate that the plant NLR N associates with the SPL6 protein in the nucleus to activate successful immune response against Tobacco Mosaic Virus (TMV). SPL6 is also required for NLR RPS4-mediated defense against Pseudomonas syringae bacteria expressing AvrRps4 effector. Therefore, SPL6 appears to be a conserved nuclear component that acts as a bridge between an activated NLR and induction of defense genes. In this project, the investigators will use a combination of genetic, molecular, biochemical, genomics, proteomics, and cell biology based approaches to understand the subcellular dynamics of NLRs during immune signaling. Precise function of SPL6 during immune signaling will be determined by identification and characterization of direct target genes that are regulated by SPL6. Also SPL6 interacting proteins will be identified and characterized. Results from the project will advance the field of immunity by providing mechanistic insights into NLRs function especially with respect to their spatial distribution and dynamics during defense. Knowledge gained will improve our understanding of plant immunity, help harness it to aid in the development of pathogen resistant crops and promote food security.