Regulation of aging in flowers of Ipomoea tricolor by ethylene.

Flowers of Ipomoea tricolor Cav. open early in the morning and fade in the afternoon of the same day. Senescence, as manifested by curling-up of the corolla and by increase in RNase activity, can be induced prematurely by treatment with ethylene (C2H4). Conversely, aging of the flower can be delayed by treatment with CO2 or by absorption of endogenously produced C2H4 with mercuric perchlorate. C2H4 given for 20 or 40 min and removed before any signs of senescence can be observed also advances the onset of aging. In untreated flowers, fading of the corolla coincides with a sharp increase in the rate of endogenous C2H4 production. A 60-min treatment with C2H4 induces an immediate increase in the rate of endogenous C2H4 formation. A model is proposed to explain the mechanism by which C2H4 may induce C2H4 synthesis.