Regulation of Growth in Avena Stem Segments by Gibberellic Acid and Kinetin
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چکیده
Kinetin at physiological concentrations causes significant reduction of GA3-promoted growth in excised Avena stem segments. Kinetin is therefore considered to be a gibberellinantagonist in this system. A Eineweaver-Burke plot reveals that kinetin acts non-competitively with GAa. The kinetin inhibition of GA3-promoted growth can be seen within 6 hours. It was found that soluble protein is markedly increased by kinetin in the tissue during the first 3 hours, thus preceding the inhibition of GAs-promoted growth by several hours. At the cellular level, kinetin negated the blocking effect of GA3 on cell division in the intercalary meristem portions of these segments. In fact, kinetin promotes both lateral and longitudinal cell divisions in intercalary meristem cells.
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