Cultivar differences in regulation of ethylene production in miniature rose flowers (Rosa hybrida L.)

In Rosa hybrida 'Bronze' ethylene exposure resulted in an increased ethylen e production of flowers, presumably as a result of an upregulation of (1-am inocyclopropane-1-carboxylic acid) oxidase and ACC synthase. At the same ti me ethylene exposure caused a considerable increase in ACC content, indicat ing that ACC synthase activity was enhanced by a larger factor than ACC oxi dase activity. In the cultivar 'Bronze' ethylene production of flowers also increased as flowers senesced, even in absence of exogenous ethylene. The ethylene production in response to exogenous ethylene was totally inhibited by treatment with the ethylene action inhibitor 1-MCP (1-methylcyclo-prope ne), while the effectiveness of 1-MCP was less efficient in senescing flowe rs. Flowers of the cultivar 'Vanilla' only produced low amounts of ethylene and did not exhibit a substantial increase in ethylene production after et hylene exposure.