| Affiliation: | (1) Department of Biological Sciences, Andong National University, 760-749 Andong, Korea;(2) Center for Cell Signaling Research, Ewha Woman’s University, 120-750 Seoul, Korea;(3) Department of Biological Science, Ewha Woman’s University, 120-750 Seoul, Korea;(4) Department of Life Science, Chung-Ang University, 156-756 Seoul, Korea |
| Abstract: | To better understand the physiological roles of brassinosteroids (BRs) in the primary roots of maize, we examined their effect on ethylene production. Exogenously applied brassinolide (BL; 10-9 to 10-7 M) incrementally increased the level ethylene in a dose-dependent manner. This BL-induced production was enhanced in the presence of IAA, thereby implying a synergistic effect between BR and IAA. At 10-7 M BL, the level of free ACC was increased, but that of conjugated ACC was diminished. Moreover, greater concentrations of BL proportionally increased ACC oxidase activity. In contrast, higher levels of IAA increased the endogenous content of conjugated ACC as well as ACC synthase activity. Based on these results, we conclude that BR activates ethylene production mainly via ACC oxidase, and interacts with IAA to produce ethylene. However, the functional site for ethylene production is different for each hormone. |
