MAIZE ACCUMULATES CHEMICAL DEFENSES DURING EARLY DEVELOPMENT, INCLUDING THE C-GLYCOSYLFLAVONE MAYSIN. MAYSIN PROTECTS MAIZE AGAINST LEPIDOPTERAN PESTS, HIGHLY ACCUMULATES IN LEAVES AND STEMS OF YOUNG PLANTS, AND EVIDENCE SUGGESTS COMPETITION WITH PHENOLICS ESSENTIAL FOR GROWTH. BUILDING ON STRONG PRELIMINARY RESULTS AND COLLABORATIONS, THE MAIN OBJECTIVE IS TO UNDERSTAND THE METABOLIC INTERACTIONS OF DEFENSIVE COMPOUNDS (E.G., MAYSIN) AND GROWTH COMPOUNDS THAT INCLUDE THE FLAVONE TRICIN (A LIGNIN MONOMER), CELL WALL CROSSLINKING HYDROXYCINNAMIC ACIDS (HCAS), AND LIGNIN PRECURSORS.WE WILL USE THE SPECIFICITY AND RESOLUTION OF MATRIX-ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY IMAGING (MALDI-MSI) TO IMAGE WHICH CELLS IN STEMS AND LEAVES OF YOUNG MAIZE PLANTS ACCUMULATE MAYSIN, TRICIN, HCAS, MONOLIGNOLS AND OTHER PHENOLICS. WE WILL COMPARE WILD TYPE AND MUTANTS UNABLE TO MAKE FLAVONOIDS IN GENERAL, OR MAYSIN IN PARTICULAR. TO UNDERSTAND THE IMPACT OF NATURAL VARIATION IN THE LOCALIZATION OF MAYSINAND ON OTHER PHENOLICS, WE WILL IMAGE ELITE MAIZE LINES WITH HIGH AND LOW MAYSIN. WE WILL PROFILE AND QUANTIFY BY LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY (LC-MS/MS) METABOLITES IN LINES DISRUPTED IN THE ACCUMULATION OF ALL FLAVONOIDS, JUST MAYSIN, OR VARIOUS LIGNINS. WE WILL INVESTIGATE THE EFFECT OF ENVIRONMENTAL CONDITIONS AND HYBRDIZATION. USING ISOTOPIC LABELING, WE WILL KINETICALLY DETERMINE HOW PHOTOSYNTHATE IS ALLOCATED BETWEEN DEFENSE AND GROWTH COMPOUNDS AND HOW THIS BALANCE CAN BE PERTURBED.