Regulation of Senescence

Flowers can be classified as either ethylene-sensitive or -insensitive based upon their responsiveness to exogenously supplied ethylene (Woltering and van Doorn, 1988). In many of the ethylene-sensitive flowers ethylene appears to be the natural regulator of senescence or floret abscission (carnation, petunia, morning glory, snapdragon). In these flowers, ethylene production rises during natural senescence or abscission, and pretreatment with inhibitors of ethylene production or action extends flower longevity. In another important group, the "ethylene-insensitive" flowers (iris, daylily, tulip, sandersonia), there is no significant increase in ethylene production during natural senescence, and inhibitors of ethylene production and action have no effect on flower longevity.

Flowers and other plant organs are able to respond to ethylene because of the presence of an ethylene transduction signaling pathway. For a review of the components of this pathway and their interaction see Chapter 24.

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