The objectives of this research are to investigate the properties of novel peptide defense signals discovered in tomato and Arabidopsis plants that have important roles in amplifying the defense systems of the plants to strengthen the resistances against pathogens and insect pests. Until the discovery of the defense peptide called systemin in tomato leaves in 1991 by Ryan and colleagues, no peptide signals were known to be components of plant signaling. Over 20 peptide signals are now known that regulate both defense and development. A novel, rapid, and simple assay has been developed in the Ryan laboratory that can identify new peptide signals in plant extracts. This assay has allowed the discovery of several new peptide signals for both plant defense and development including a peptide called AtPep1 that enhances the innate immune responses of the plants against pathogens. The gene encoding the peptide is a member of a gene family that is found in species throughout the plant kingdom. Biochemical, molecular, and genetic approaches will be carried out to understand the role of peptide signals using tomato and Arabidopsis plants as model systems. The localization of the peptides and their precursor genes in plants will be studied, and how the peptides are produced from precursor proteins and perceived by plant cells to activate defensive genes in response to herbivores and/or pathogen attacks will be investigated. The peptides that enhance plant defense responses have provided new insights toward an understanding of innate immunity in plants, which are the earliest responses of plants in response to most attacking organisms. The knowledge gained will contribute to the framework of the basic principles that govern peptide signaling in the plant kingdom. Such information will contribute to an understanding of defense peptide signaling in both plants and animals, and will be especially useful in breeding and biotechnological approaches to enhance yields in major agricultural crops. A major component of this grant is to train undergraduate and graduate students as well as postdoctoral fellows and visiting scientists in fundamentals research that can be applied to agriculture and human health. The PI's successful ongoing efforts to bring women and minorities into my laboratory will continue through the tenure of this project.
