POLLINATION-INDUCED ETHYLENE IN CARNATION

The pollen-pistil interactions that result in the stimulation of ethyl ene production and petal senescence in carnation (Dianthus caryophyllu s L.) flowers were investigated. pollination of White Sim flowers with Starlight pollen elicited an increase in ethylene production by style s, leading to increased petal ethylene and premature petal senescence. In contrast, pollination with 87-29G pollen led to an early increase in ethylene production, but this was not sustained, and did not lead t o petal senescence. Both Starlight and 87-29G pollen germinated on Whi te Sim stigmas and their tubes grew at similar rates, penetrating the length of the style. Crosses between Starlight and White Sim led to th e production of viable seeds, whereas 87-29G pollen was infertile on W hite Sim flowers. Pollination of other carnations with 87-29G elicited ethylene production and petal senescence and led to the production of viable seeds. These results suggest that physical growth of pollen tu bes is insufficient to elicit a sustained increase in ethylene product ion or to lead to the production of signals necessary for elicitation of petal ethylene production and senescence. Rather, the cell-cell rec ognition reactions leading to sexual compatibility in Dianthus appear to play a role in this interorgan signaling after pollination.