THIS PROJECT SUPPORTS THE MISSION OF THE AGRICULTURAL EXPERIMENT STATION BY ADDRESSING THE HATCH ACT AREA(S) OF: PLANT AND ANIMAL PRODUCTION, PROTECTION, AND HEALTH; HUMAN NUTRITION; AND SUSTAINABLE AGRICULTURE; AND MOLECULAR BIOLOGY. MAIZE VARIETIES WITH INCREASED GRAIN CAROTENOID (PROVITAMIN A) AND TOCOCHROMANOL (VITAMIN E) CONCENTRATION HAVE BEEN IDENTIFIED AS AN EFFECTIVE INTERVENTION FOR IMPROVED NUTRITIONAL STATUS IN DEVELOPING NATIONS AND CERTAIN POPULATION SEGMENTS OF DEVELOPED NATIONS, INCLUDING THE U.S. THESE TRAITS ARE EXPENSIVE TO QUANTIFY IN THE LAB AND ARE CONTROLLED BY RELATIVELY FEW, LARGE-EFFECT LOCI IN THE GENOME, MANY OF THEM CODING FOR ENZYMES IN THE DIRECT BIOCHEMICAL PATHWAY THAT PRODUCES THESE NUTRITIONAL COMPOUNDS. THUS, PREDICTION MODELS BASED ON GENETIC MARKERS THAT TARGET THESE LOCI MAY PROVIDE A HIGHLY ACCURATE, MORE EFFICIENT, AND LOWER-COST STRATEGY FOR IMPROVING LEVELS OF THESE NUTRIENTS IN MAIZE THROUGH BREEDING. THIS PROJECT WILL DEVELOP HIGHLY ACCURATE GENOMICS-BASED PREDICTION MODELS IN A PANEL OF APPROXIMATELY 5,000 MAIZE INBRED LINES. THE PANEL WAS DEVELOPED BY CROSSING 25 DIVERSE PARENTS FOR MANY GENERATIONS TO BREAK THE GENOME INTO SMALLER PIECES THROUGH CHROMOSOMAL CROSSOVER EVENTS, OR RECOMBINATION, AND THUS INCREASE RESOLUTION FOR FINDING THE IMPORTANT GENETIC LOCI. THE PREDICTION MODEL FOR THIS PANEL WILL BE BUILT UPON AND EXPANDED FROM PREVIOUS FINDINGS IN A SUBSTANTIALLY SMALLER MAIZE INBRED DIVERSITY PANEL FOR USE IN BREEDING FOR IMPROVED LEVELS OF CAROTENOIDS AND TOCOCHROMANOLS. FURTHER, THERE IS AN URGENT NEED BOTH WITHIN PROVITAMIN A BREEDING EFFORTS AND MORE GENERALLY TO DEVELOP VARIETIES THAT WILL BE HIGHLY PRODUCTIVE EVEN AS CLIMATE CHANGE TAKES PLACE AT THE GLOBAL LEVEL AND EXERTS ITS IMPACTS REGIONALLY. IN THIS LIGHT, 350 SUBTROPICALLY ADAPTED MAIZE HYBRIDS ARE BEING EVALUATED IN SOUTHWEST ZIMBABWE UNDER COMBINED DROUGHT AND HEAT STRESS VS. HEAT STRESS ONLY (WELL-WATERED) CONDITIONS, IN COLLABORATION WITH THE INTERNATIONAL MAIZE AND WHEAT IMPROVEMENT CENTER (CIMMYT). GENETIC AND GENOMIC ANALYSES WILL BE CONDUCTED FOR YIELD AND OTHER AGRONOMIC TRAITS OF INTEREST, AND METHODS WILL BE SHARED WITH AND TAUGHT INTERACTIVELY TO STUDENTS AND FELLOW RESEARCHERS IN THE U.S., ZIMBABWE, AND EASTERN AFRICA. KEY OBJECTIVES WILL BE TO IDENTIFY THE GENETIC LOCI CONTRIBUTING TO NATURAL VARIATION IN YIELD PERFORMANCE UNDER COMBINED DROUGHT AND HEAT STRESS VS. HEAT ONLY (WELL-WATERED), AND TO PREDICT YIELD PERFORMANCE BASED ON GENETIC INFORMATION. WITHIN THIS WORK, INBRED AND HYBRID LINES EXHIBITING FAVORABLE PERFORMANCE WILL BE IDENTIFIED AND INCORPORATED INTO BREEDING PROGRAMS FOR ORANGE, PROVITAMIN A-DENSE MAIZE, AND THE IDENTIFIED GENETIC LOCI WILL BE USED (INCLUDING THROUGH USE OF GENOMIC PREDICTION MODELS) TO REFINE SELECTION STRATEGIES. THESE OUTCOMES ARE OF IMMEDIATE INTEREST TO MAIZE BREEDERS AND CONSUMERS IN THE U.S., SOUTHERN AFRICA, AND ELSEWHERE IN ENSURING A FOOD SUPPLY THAT IS SUFFICIENT IN QUANTITY AND QUALITY IN THE LONG TERM.