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Title: CHANGES IN IONS AND PROTEINS IN PITH OF INTERNODES OF A SHRUNKEN2 SWEET MAIZE AT FOUR DEVELOPMENTAL STAGES

Author
item Russo, Vincent
item BILES, C - EAST CENTRAL UNIVERSITY

Submitted to: Cereal Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/1997
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 based on the amount of dead tissue present. Concentrations of mineral elements and sugars, and distribution of proteins were determined with analytical equipment as plants passed from mid-whorl (internodes completely juvenile) to fresh-market maturity (internodes exhibiting stages of senescence). In internode pith tissue concentrations of Mg, NO3, or SO4 were negatively correlated with senescence rating and fewer proteins were present at fresh-market maturity than before. It remais 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 senescence, concentration of mineral elements and distribution of proteins 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). Internodes near the stalk base (I7), ,below the ear (I9), and above the ear (I11) were rated for senescence. Tissues were extracted and analyzed by automated ion analysis. Senescence rating increased from V9 to FM. Concentrations of N, P, K, Fe, Mn, NO2, NO3, PO4, SO4, Na, Mg, and Ca generally were reduced as plants aged. Exceptions were in I7 and I9 where P fluctuated, and Na was unchanged, and in I11 where P, Na, Mg, and SO4 were unchanged. Senescence at VT, silk emergence (R1), and FM was negatively correlated with P, Cl, and Na. Senescence in I7 and I9 was negatively correlated with Mg, NO3 or SO4. Few protein bands were between 14.4 and 97.4 kD at V9 and FM, but several were at VT and R1. Reduction in sucrose and glucose concentrations, negative correlations with some mineral elements, and changes in protein distribution may be indications of the onset of senescence.