Chemical information transfer between wounded and unwounded plants: backing up the future

This special issue on "Chemical information transfer between wounded and unwounded plants" provides an overview of past and ongoing experiments on plant-to-plant communication. Since the studies on plant responses to single gaseous compounds were not particularly emphasised, the actual number of studies relevant to the subject is underestimated. All in all, we think the amount of data on damage-induced plant-to-plant information transfer makes that the phenomenon can no longer be denied and deserves intensified attention by the scientific community. In this epilogue we highlight a couple of issues which received little attention and present some speculative ideas. First we concentrate on functional aspects of plant-plant communication we stress the concept of damage-induced signalling as an ecological cost to the signal-sending plant and we discuss the theoretical development on interplant signalling, which is still in its infancy. With respect to mechanisms, we compare above- to belowground signalling, discuss potential cues and stress the possibility that responses in signal-exposed plants may be hidden. Finally, we address some future prospects which may help in the further development of the still underexposed phenomenon of damage-induced plant-to-plant information transfer. (C) 2001 Elsevier Science Ltd. All rights reserved.