Gametophyte-sporophyte interactions in the pollen-pistil system: 2. The evolution of ethylene and CO2 after pollination

The evolution of ethylene and CO2 from different parts of petunia (Petunia hybrida L.) pistils (stigma, style, and ovary) was monitored for 8 h after self-compatible pollination. The growth of the male gametophyte was accompa nied by the active evolution of ethylene from sporophytic tissues of the pi stil. Over the first 4 h after pollination, the growth of the pollen tube w as accompanied by a twofold acceleration of ethylene evolution from pistil tissues, but this rate decreased slightly over the subsequent 4 h. Pollinat ion also stimulated the CO2 evolution, which indicates the implication of e thylene in oxidative processes during the pollen tube growth. It is conclud ed that the stigma is the main site of ethylene synthesis, both in pollinat ed and nonpollinated pistils. The results suggest the involvement of ethyle ne in the hormonal regulation of gametophyte-sporophyte interactions in the pollen-pistil system.