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Parameters of Filament Elongation in Ipomoea nil (Convolvulaceae)

Ross E. Koning and Mandy M. Raab
American Journal of Botany
Vol. 74, No. 4 (Apr., 1987), pp. 510-516
Stable URL: http://www.jstor.org/stable/2443830
Page Count: 7
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Parameters of Filament Elongation in Ipomoea nil (Convolvulaceae)
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Abstract

It has been thought for some time that morning glory filaments elongate in response to changes in concentrations of gibberellins (Murakami, 1973), but many other aspects of their growth have remained unstudied. In the present work, the interacting roles of gibberellin and ethylene in filament growth were examined. Filaments elongated ten-fold by epidermal cell elongation accompanied by ten-fold increases in fresh and dry weight. Applied gibberellins could stimulate filament growth in vitro, but gibberellin biosynthesis inhibitors had no effect. The putative gibberellin action inhibitor, ancymidol, reduced growth but the inhibition could be removed by blocking ethylene biosynthesis. Stimulators of the ethylene biosynthesis pathway and applied ethylene precursor (ACC) strongly inhibited filament elongation; ethylene biosynthesis inhibitors elicited as much growth as applied gibberellin. The filaments produced little ethylene at the time of the onset of growth. While the filaments produced ethylene rapidly before and after growth initiation, the closed flower bud had a relatively constant level of ethylene. It seems likely that in situ production of ethylene negatively influences filament growth.

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