Abstract
Abscission of organs from the plant body can be both developmentally and environmentally regulated. The course of the abscission process is strongly influenced by plant hormones, among them ethylene (ET). Hormones are coordinators of all changes that occur in the abscission zone (AZ), where the ultimate molecular and cellular processes that lead to organ detachment occur. Most of the recent studies regarding abscission aimed to examine the regulation of central pathways and subsequent steps functioning in the AZ. The focus of this chapter addresses ET involvement in the local transformations that occur within the AZ. Specifically, ET-dependent gene expression and enzymatic activities that control the initiation and execution of abscission processes are required in the AZ, given that these cells respond preferentially to ET and some cells may undergo programmed cell death. However, to understand the role of ET in these processes, we also considerthe changes that take place in the to be detached organ, which can also be a source of abscission-inducing signals. Therefore, the contribution of ET to changes that take place in the organ that undergoes abscission processes is also highlighted. Furthermore, abscission involves ET signaling and requires the coordinated action of different phytohormones, e.g. auxins and abscisic acid. Thus, ET interactions with other signaling molecules is the focus of the last section. Although great progress has been made in recent years in the understanding of ET responsiveness during abscission events, many questions still have to be answered. We believe that this chapter summarizes the body of knowledge about this phenomenon and can be a basis for researchers who are fascinated by abscission processes. We also hope that it provides a useful basis for other scientists to consider the exploration of this extremely interesting scientific area and improveour knowledge about organ separation.