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

This special issue on "Chemical information transfer between wounded and un wounded plants" provides an overview of past and ongoing experiments on pla nt-to-plant communication. Since the studies on plant responses to single g aseous compounds were not particularly emphasised, the actual number of stu dies relevant to the subject is underestimated. All in all, we think the am ount of data on damage-induced plant-to-plant information transfer makes th at the phenomenon can no longer be denied and deserves intensified attentio n by the scientific community. In this epilogue we highlight a couple of is sues which received little attention and present some speculative ideas. Fi rst we concentrate on functional aspects of plant-plant communication we st ress the concept of damage-induced signalling as an ecological cost to the signal-sending plant and we discuss the theoretical development on interpla nt signalling, which is still in its infancy. With respect to mechanisms, w e compare above- to belowground signalling, discuss potential cues and stre ss the possibility that responses in signal-exposed plants may be hidden. F inally, we address some future prospects which may help in the further deve lopment of the still underexposed phenomenon of damage-induced plant-to-pla nt information transfer. (C) 2001 Elsevier Science Ltd. All rights reserved .