Nuclear Magnetic Resonance for Monitoring Carbon Metabolism in Sweet Corn

Abstract

Understanding carbon metabolism can provide insight into physiological processes regulating yield, senescence, and resistance to pathogens in sweet corn (Zea mays L.). This study was conducted to determine if nuclear magnetic resonance (NMR) spectroscopy could be used to monitor changes in carbon metabolism at various growth stages in the shrunken-2 sweet corn cultivar Illini Gold. The 7th, 9th, and 11th stalk internodes were excised at midwhorl (V9), tassel emergence, 50% silking, and fresh-market harvest stages. The rind was removed and the sap expressed. Carbon-NMR spectroscopy was conducted with a 200.7 MHz machine on the expressed sap. From V9 through 50% silking, peaks in spectra were uniformly grouped from ≈61 to ≈104 ppm. At fresh-market stage, additional peaks were found in the spectra at ≈17 to ≈20 ppm, with the majority of peaks found from ≈57 to ≈104 ppm. The biological importance of these changes in carbon metabolism in sweet corn are not clear. Efforts are under way to identify the carbon-based compounds associated with the peaks.