Michael A. Lawton - US grants

9418975 Lawton This award deals with the PR5K gene from Arabidopsis thaliana which encodes a novel receptor with structural features related to plant defense proteins. The kinase domain of PR5K is presumed to be involved in cytoplasmic signal transduction. The extracellular domain is closely related to a group of antimicrobial proteins that includes the pathogenesis protein PR-5, osmotin, thaumatin and a bifunctional inhibitor of maize. By analogy with other receptor kinases, this domain is the predicted binding site for a polypeptide ligand. The structural relationship between the extracellular domain of PR5K and known pathogenesis-related proteins suggests a possible functional relationship in the expression of the defense response. Thus, cellular targets of antimicrobial proteins such as PR5 might also serve as ligands for activation of the PR5K receptor. A close structural relationship is also seen for the secreted and kinase-linked forms of the S-locus glycoproteins of Brassica and these molecules have been proposed to form a functional unit that specifies self- incompatibility during pistil-pollen interactions. This proposal is concerned with characterizing the PR5K receptor and dissecting its possible role in the perception of plant defense signals.

9729526 Lawton This U.S.-Brazil award will support research collaboration between Dr. Michael A. Lawton of Rutgers University and Drs. Marcio Lamais and Helaine Carrer of Universidade de Sao Paulo in Brazil. Most plants undergo a symbiotic interaction with arbuscular mycorrhizal (AM) fungi. This interaction is important for nutrient assimilation and for plant growth and health, yet there is scant information regarding the molecular and genetic basis for AM colonization of plants. The investigators plan to use gene tagging techniques to characterize plant genes whose expression is associated with specific stages of AM infection. The three investigators each bring a unique expertise to this project. Dr. Lambais is an expert in plant:AM interactions, Dr. Carrer is expert in plant transformation and molecular genetics, and Dr. Lawton in molecular biology of plant:pathogen interactions. The final result of this work will be a collection of tagged plants that will be of general use, made freely available to the research community. ***

Diatoms are microscopic aquatic organisms that are collectively responsible for approximately 20% of the photosynthetic activity on Earth. However, little is known of the response of these important organisms to changes in their environment. The primary goal of this project is to understand how these organisms sense the environment and alter their physiology to optimize their growth and productivity. This project will develop important novel tools that are anticipated to be of broad value to the research field, and will elucidate the mechanisms by which changes in the environment influence cell physiology. It will provide research opportunities for undergraduates and advance public science education.

This project will elucidate how simple environmental signals lead to rapid and reversible physiological responses in a model marine diatom Phaeodactylum tricornutum. The signal transduction pathways that facilitate these responses are virtually unknown. The hypothesis will be tested that retrograde signals emanating from the electron transport system in the plastid are the primary means by which diatoms translate environmental signals into nuclear gene expression, leading to reversible physiological responses. Based on a bioinformatics analysis, a reverse genetics approach will initially be used to target five genes hypothesized to represent major components of the retrograde signal transduction system in diatoms. The project will utilize a rapid and robust gene-editing approach based on CRISPR/Cas9 technology, combined with a technique based on self-processing ribozyme sequences that flank the guide RNA to target the genes encoding the putative signal transduction proteins.