Interorgan Signaling following Pollination in Carnations

Abstract

Following a compatible pollination in carnation (Dianthus caryophyllus L. `White Sim'), a signal that coordinates postpollination events is translocated from the style to the ovary and petals. In this paper the roles of ethylene and its direct precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), in this signaling were investigated. Following pollination, ethylene and ACC increased sequentially in styles, ovaries, and petals. Ethylene and ACC were highest initially in the stigmatic region of the style but by 24 hours after pollination were highest in the base. Activity of ACC synthase correlated well with ethylene production in styles and petals. In ovaries, ACC synthase activity decreased after pollination despite elevated ethylene production. Lack of ACC synthase activity in pollinated ovaries, coupled with high ACC content, suggests that ACC is translocated within the gynoecium. Further, detection of propylene from petals following application to the ovary provided evidence for movement of ethylene within the flower. Experiments that removed styles and petals at various times after pollination suggest there is a transmissible pollination signal in carnations that has reached the ovary by 12 hours and the petals by 14 to 16 hours.