ISHS Acta Horticulturae 181: III International Symposium on Postharvest Physiology of Ornamentals
POLLINATION-INDUCED COROLLA SENESCENCE |
| Author: | A. H. Halevy |
| Abstract:
Pollination causes considerable acceleration of senescence symptoms in the petals, such as discoloration, wilting, anthocyanin synthesis and abscission. Since the pollen germinates in the pistil and the senescence symptoms appear in the petals, senescence signal(s) must be transmitted from the gynoecium to the corolla. The pollination-induced corolla senescence is unrelated to fertilization. Ethylene production by pollinated flowers is initially promoted by ACC transferred from the pollen and later by the stimulation of ACC-synthase in the pistil by the germinating pollen tubes. The ACC produced by the gynoecium is translocated towards the corolla, inducing an early climacteric burst of ethylene, concomitantly with the appearance of the typical senescence symptoms. Pollination also enhances the sensitivity of the corolla to ethylene. A yet unidentified "sensitivity factor" is apparently transmitted from the pollinated gynoecium to the corolla rendering it sensitive to the senescence-promoting effects of ethylene. The lower portions of carnation petals and petunia corollas transmit ACC to the upper portions where it is oxidized to ethylene. The basal parts also produce a "sensitivity factor" to ethylene. This factor is being produced also in nonpollinated flowers, but its production is enhanced after pollination. | |
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