** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SOME PLANTS, SUCH AS CORN, PERFORM A RARE TYPE OF PHOTOSYNTHESIS CALLED C4 PHOTOSYNTHESIS. C4 PHOTOSYNTHESIS IS MORE EFFICIENT AND DROUGHT TOLERANT THAN C3 PHOTOSYNTHESIS, THE TYPE PERFORMED BY MOST OTHER PLANTS. ONE LONG-STANDING GOAL IN PLANT SCIENCE HAS BEEN TO CHANGE C3 CROP PLANTS (SUCH AS RICE) SO THAT THEY PERFORM C4 PHOTOSYNTHESIS INSTEAD, MAKING THEM MORE DROUGHT TOLERANT. FOR C4 PHOTOSYNTHESIS TO BE POSSIBLE, A PLANT MUST HAVE DENSELY ARRANGED VEINS IN ITS LEAVES AND A SPECIALIZED CELLULAR ANATOMY. HOWEVER, WE DO NOT UNDERSTAND THE DEVELOPMENTAL MECHANISMS THAT LEAD TO THIS DENSE VENATION AND CELLULAR ANATOMY. VASCULAR ANATOMY AND SPACING ARE THEREFORE CRUCIAL TARGETS FOR CROP IMPROVEMENT AND CLIMATE RESILIENCE. THE OVERALL GOAL OF THIS PROJECT IS TO IDENTIFY GENES RELATED TO VEIN INITIATION AND SPACING IN THE LEAVES OF CORN.TO IDENTIFY GENES RELATING TO VEIN DEVELOPMENT AND SPACING, THIS PROJECT USES THREE SEPARATE APPROACHES. FIRST, WE WILL PERFORM A GENOME-WIDE ASSOCIATION STUDY TO ASSOCIATE MEASUREMENTS OF VEIN DENSITY ACROSS MANY KINDS OF CORN WITH AVAILABLE DATA OF GENETIC VARIATION. WE ARE USING A NEURAL-NETWORK COMPUTER VISION TOOL TO QUANTIFY AND MEASURE THESE MICROSCOPIC VEIN TRAITS IN SCANNED IMAGES OF CORN LEAVES. THIS WILL TELL US WHICH GENES ARE ASSOCIATED WITH VARIATION IN MEASURED VEIN TRAITS. SECOND, WE WILL USE SINGLE-CELL RNA SEQUENCING TO PROFILE THE GENE EXPRESSION OF INDIVIDUAL CELLS IN DEVELOPING CORN LEAVES AT VERY EARLY STAGES. THIS TECHNIQUE WILL ALLOW US TO DETERMINE WHICH GENES ARE EXPRESSED IN CERTAIN CELL TYPES, SUCH AS THE CELLS THAT WILL BECOME VEINS. BY DOING SO, WE WILL BE ABLE FIND CURRENTLY UNKNOWN GENES THAT ARE INVOLVED IN EARLY VEIN DEVELOPMENT AND POSITIONING. THIRD, WE WILL CHARACTERIZE AN ANATOMICAL DEFECT THAT WE FOUND OCCURRING IN MANY TYPES OF CORN THAT DIRECTLY AFFECTS THE SPECIALIZED ANATOMY NECESSARY FOR C4 PHOTOSYNTHESIS. FINDING OUT HOW THIS DEFECT OCCURS ON A CELLULAR LEVEL WILL ALLOW US A BETTER UNDERSTANDING OF HOW THIS SPECIALIZED ANATOMY DEVELOPS NORMALLY. BY THE END OF THIS PROJECT, WE SHOULD HAVE NEW KNOWLEDGE OF PREVIOUSLY UNKNOWN GENES THAT INFLUENCE VEIN SPACING AND DEVELOPMENT IN CORN. THIS WOULD BE AN IMPORTANT STEP TOWARDS ONE DAY BEING ABLE TO GENETICALLY ENGINEER EFFICIENT C4 PHOTOSYNTHESIS INTO C3 CROPS, THEREBY MAKING THEM MORE DROUGHT TOLERANT IN A WARMER AND DRIER WORLD.