Collaborative Research: Signals, Genes, and Metabolites in Defense Priming Mediated by 12-oxo-phytodienoate Reductases in Maize

University Of Texas At San Antonio, San Antonio TX

Investigators

Abstract

Green leafy volatiles (GLVs), the odor typically associated with wounded or cut plants, are potent signaling molecules involved in the regulation of plant defense against insect herbivores and pathogens. In addition to activating direct responses, GLV exposure prepares non-infested plants for subsequent attack by pests and pathogens by activating mechanisms that prime the plant for a faster and more intensive response to an actual infestation. Among the genes up-regulated in maize in response to GLV exposure are several members of the 12-oxo-phytodienoate reductase (OPR) gene family. Increased expression is accompanied by an increase in total OPR enzyme activity at the time of priming. OPRs seem to play a significant role not only in the regulation of the octadecanoid signaling pathway with jasmonates as the end-product, but also in the regulation of other important defense signals.. The goal of this project is to comprehensively analyze the biochemical and physiological roles of six maize OPR family members in the priming of defense responses to insect herbivores and pathogens and in the regulation of direct defenses. This class of proteins will be analyzed biochemically, molecularly, and genetically by using transposon-insertional OPR mutants of maize and by testing the recombinant OPR proteins in vitro. In addition, global changes in GLV-induced gene expression will be monitored and the role of these 'primed' changes in direct defense responses will be analyzed. Priming-induced marker genes will be further characterized by real-time PCR in the opr mutants. Defense priming to insect herbivory and diseases is an emerging exciting but little understood area in plant biology. This project aims to provide basic knowledge about potential molecular and biochemical mechanisms of priming and will eventually help to develop environmentally sound pest and pathogen management strategies. Results will be broadly disseminated through publications, incorporation into textbooks and coursework, and press releases to local newspapers and web-based journals. The project is multidisciplinary in nature and will provide participating undergraduate and graduate students with an integrative experience by combining such diverse areas as molecular biology, biochemistry, entomology, plant pathology, chemical ecology and many more. Educational efforts also include recruitment of students from groups underrepresented in the sciences to the research groups at both campuses and outreach to local high school teachers and students.