INHIBITION OF ETHYLENE-INDUCED CELLULAR SENESCENCE SYMPTOMS BY 1-METHYLCYCLOPROPENE, A NEW INHIBITOR OF ETHYLENE ACTION

Ethylene is known to accelerate flower senescence, but the sequence of events that links its interaction with the tissue and the final senes cence symptoms is still obscure. Recently, 1-methylcyclopropene (1-MCP ) was found to inhibit ethylene-induced wilting in flowers. This work was carried out in order to investigate the effects of 1-MCP on cellul ar senescence symptoms in petunia flowers following exposure to ethyle ne. Cut petunia (Petunia hybrida) flowers that were exposed to ethylen e for 12 h at concentrations of 1-12 ppm wilted sooner than their untr eated counterparts. This effect was abolished by a 6-h pre-treatment w ith 1-MCP. Immediately following the ethylene treatment, decreases in petal fresh weight and total protein content were measured, along with higher electrolyte leakage, and lower membrane lipid fluidity and pro tein content. When applied alone, 1-MCP had relatively little impact o n these parameters. However, when the flowers were treated with 1-MCP prior to the ethylene treatment, ethylene had no effect. These results indicate that while ethylenes effects on wilting were obvious 3 days after the treatment, cellular parameters were affected already at the end of the treatment. Since 1-MCP repressed these early ethylene effec ts, it was concluded that it interferes with ethylene action in petuni a flowers at a rather early stage, long before apparent wilting.