**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** IN THEIR NATURAL HABITATS, PLANTS ARE EXPOSED TO SEVERE BIOTIC AND ABIOTIC STRESSES THAT REDUCE THEIR FITNESS AND SURVIVAL. EACH YEAR, A SIZABLE FRACTION OF GLOBAL AGRICULTURAL PRODUCTIVITY IS LOST TO INSECT AND PATHOGEN ATTACK. MAIZE (ZEA MAYS), THE WORLD'S MOST PRODUCTIVE FOOD CROP, IS ATTACKED BY MORE THAN 90 SPECIES OF PEST INSECTS THAT DEVOUR ITS LEAVES, STEMS, SILK, EARS, AND ROOTS, RESULTING IN A 9-16% LOSS IN OVERALL PRODUCTIVITY. GIVEN THAT A MAJORITY OF THE HUMAN DIET DEPENDS DIRECTLY OR INDIRECTLY ON MAIZE AND A FEW RELATED CROPS, IT IS IMPERATIVE TO INVESTIGATE THE NATURAL INSECT DEFENSE RESPONSES IN THESE PLANT SPECIES. ONE EFFICIENT WAY IN WHICH PLANTS DEFEND THEMSELVES AGAINST HERBIVORY IS TO TURN ON THE PRODUCTION OF ENERGETICALLY COSTLY DEFENSIVE CHEMICALS ONLY WHEN THEY ARE SUBJECTED TO INSECT FEEDING. INDUCED PRODUCTION OF JASMONIC ACID, ONE OF THE MOST IMPORTANT SIGNALING MOLECULES THAT REGULATE PLANT DEFENSE AGAINST INSECT ATTACK, IS COMMONLY OBSERVED IN MAIZE. HOWEVER, DESPITE ABUNDANT RESEARCH ON THE FUNCTIONS OF JASMONIC ACID SIGNALING IN VEGETABLE CROPS SUCH AS TOMATOES, RELATIVELY LITTLE RESEARCH HAS BEEN DONE ON THIS PATHWAY IN MAIZE AND OTHER AGRICULTURALLY IMPORTANT GRASSES. FOR EXAMPLE, ALTHOUGH TOMATOES HAVE ONLY SINGLE COPIES OF SEVERAL JASMONIC ACID-RELATED GENES, MAIZE HAS LARGER NUMBERS OF THESE GENES, WHICH ARE PREDICTED TO HAVE SIMILAR BUT NOT IDENTICAL FUNCTIONS. AN INVESTIGATION OF THESE GENE FAMILIES WILL LEAD TO A BETTER UNDERSTANDING OF HOW NATURAL VARIATION IN JASMONIC ACID SIGNALING PATHWAYS INFLUENCES DEFENSE RESPONSES IN MAIZE. IN TURN, THIS WILL MAKE IT POSSIBLE TO BREED MAIZE VARIETIES WITH NATURALLY ENHANCED RESISTANCE TO INSECT PESTS.WE WILL USE A COMBINATION OF GENETIC AND BIOCHEMICAL APPROACHES TO IDENTIFY NOVEL MAIZE DEFENSE SIGNALING MOLECULES, AS WELL AS GENES INVOLVED IN THEIR BIOSYNTHESIS AND DETECTION. IN PARTICULAR, MAIZE GENES THAT CONTRIBUTE TO NATURAL VARIATION IN THE PRODUCTION OF JASMONIC ACID AND RELATED METABOLITES WILL BE IDENTIFIED BY GENETIC MAPPING STUDIES. PRELIMINARY EXPERIMENTS IDENTIFIED LOX4 AS A MAIZE GENE THAT UNDERLIES NATURAL VARIATION IN JASMONIC ACID-MEDIATED DEFENSE SIGNALING. FURTHER RESEARCH WILL INVOLVE USING METABOLOMICS, TRANSCRIPTOMICS, AND INSECT BIOASSAYS TO INVESTIGATE THE ROLE OF LOX4 IN MAIZE DEFENSE AGAINST CATERPILLAR FEEDING. IN ANOTHER APPROACH, WE WILL INVESTIGATE A FAMILY OF COI GENES, WHICH ENCODE RECEPTORS THAT ARE REQUIRED FOR THE INDUCTION OF CATERPILLAR DEFENSES. ALTHOUGH THERE ARE AT LEAST SIX COI GENES IN MAIZE, THEIR INDIVIDUAL FUNCTIONS IN PLANT DEFENSE HAVE NOT YET BEEN ELUCIDATED.AS AN INTEGRAL COMPONENT OF THIS PROJECT, UNDERGRADUATE STUDENTS WILL RECEIVE RESEARCH TRAINING THROUGH LABORATORY CLASSES, INDEPENDENT RESEARCH PROJECTS, AND FULL-TIME SUMMER INTERNSHIPS. THE INVOLVEMENT OF ESTABLISHED RECRUITMENT PROGRAMS AT THE HOST INSTITUTIONS WILL HELP TO PROMOTE THE PARTICIPATION OF UNDERREPRESENTED MINORITY STUDENTS IN PLANT RESEARCH. COMMUNITY OUTREACH PROGRAMS, PARTICULARLY ONES INVOLVING LOCAL HIGH SCHOOL STUDENTS, WILL BE USED TO PROVIDE INFORMATION ABOUT THE IMPORTANCE OF PLANT DEFENSE SIGNALING TO THE GENERAL PUBLIC.