The microtubule network and cell wall-based extracellular immunity

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

When pathogenic microorganisms infect plants, they respond by having plant cells release many different substances outside of the cell. In many instances, this collective response stops microbes from growing in this niche. However, it is mostly unknown how these substances are released by plant cells and how these substances stop pathogens from growing. Additionally, the project will identify substances that are released to the extracellular spaces during a plant immune response and determine which ones are important for the resistance to pathogens. The long-term goal of this project is to develop crops that are more resistant to pathogens. This project will offer camps for high school students within University of Nebraska, Lincoln's, Nebraska College Preparatory Academy program, targeting low-income and underrepresented minority high school students from urban centers of the state. Additionally, the project will offer research training for high school students within the Young Nebraska Scientist Program. The topics pursued in this proposal have important ramifications for plant immunity and plant biology, adding to the broad appeal of both programs to young scientists and enhancing high school student interest in STEM fields. Plant immunity triggers the release of proteins and metabolites to combat extracellular pathogens, which reside in the apoplast, the space between plant cells. While many of the products that are secreted or exported from the plant cell to the apoplast are known, it is not well understood which are important for resistance to bacterial pathogens or how they are secreted. A primary virulence strategy of the bacterial pathogen Pseudomonas syringae is to inject type III effector proteins into host cells to suppress plant immunity. Recently published indicate that the HopE1 effector targets MAP65-1 to perturb the microtubule network. HopE1 also inhibits the secretion of immunity-related proteins to the apoplast. These findings provide an entry point to better understand the involvement of microtubules in the secretion of immunity-related products to the apoplast. Arabidopsis mutants defective in MAP65-1 are more susceptible to P. syringae, and MAP65-1 over-expressing plants exhibit enhanced resistance to P. syringae. The overall goal of this project is to elucidate how MAP65 functions in the microtubule network, to better understand the involvement of the microtubule network in plant immunity, identify the apoplastic products that depend on microtubules for their secretion, and systematically mutate their corresponding genes to determine their involvement in cell wall-based extracellular immunity. The experimental methods that will be employed will range from biochemistry, molecular biology, cell biology and proteomics to newer techniques such as CRISPR-CAS9 mutagenesis. 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.