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Title: 13C-NMR SPECTROSCOPY TO MONITOR SUGARS IN PITH OF INTERNODES OF A SH2 CORN AT DEVELOPMENTAL STAGES

Author
item Russo, Vincent
item WILLIAMSON, J. - SOUTHEASTERN OK STATE UNI
item ROBERTS, K. - SOUTHEASTERN OK STATE UNI
item WRIGHT, J. - SOUTHEASTERN OK STATE UNI
item MANESS, N. - OKLAHOMA STATE UNIV.

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Maturation, sometimes termed senescence, in plants involves changes that can be described. Measurements of chemical changes associated with development in plants can be correlated, and inferences drawn concerning their biological importance. Internodes of the sweet corn (Zea mays L.) cv. Illini gold, a shrunken2 hybrid, near the base of the stalk, below an ear, and between the ear and tassel were visually rated for senescence bases on the amount of dead tissue present. Concentrations of sugars were determined with analytical equipment as plants passed from mid-whorl (internodes completely juvenile) to fresh-market maturity (internodes exhibiting stages of senescence). Concentrations of sugars decreased after tassel or silk formation. It remains to be determined if these changes are the physiological markers of the onset, or the result, of senescence.

Technical Abstract: The study was conducted to determine how concentration of sugars changed in internodes of a sh2 sweet corn (Zea mays L.), cv. Illini Gold, from mid- whorl (V9; internodes completely juvenile) to fresh-market maturity (FM; internodes with stages of senescence). Tissues were extracted and analyzed dby carbon-nuclear magnetic reasonance spectroscopy (C-nmr) and HPLC. For C-nmr chemical shifts were measured in parts per million hertz (ppm) relative to tetramethyl silane. Through R1 C-nmr spectra were similar regardless of internode with line positions between 60 and 105 ppm. Unique lines for glucose, fructose, and sucrose were at 96, 98, and 104 ppm, respectively. Sucrose was highest at R1 (26.1 mg/mL**1), fructose at tasseling (VT) and R1 (avg. 30.4 mg/mL**1), and glucose from VT (avg. 31.9 mg/mL**1). At FM an unidentified compound(s) had lines at 16.8, 17.9 and 57.5 ppm. Reduction in sucrose and glucose concentrations, may be indicators of the onset of senescence.