ABSTRACT
In recent years, discovery of genes encoding enzymes catalyzing the formation of volatile organic compounds (VOCs) enabled us to improve our understanding of the regulation of their production. As VOCs emitted by plants serve major roles from ecological (plant signaling and communication) and environmental (atmospheric chemistry) perspectives, it is rather surprising how little is known about the mechanism(s) of VOC emission. To be released from cells volatiles have to move through multi-tier barriers and until recently it was accepted that emission occurs by passive diffusion. However, recent studies provide evidence for a complex and well-regulated biologically-mediated process. Conversely, plants are continuously exposed to volatiles from the atmosphere and to volatiles emitted by other plants that may be involved in plant–plant communication. There is enough proof to date showing that plants are able to take up VOCs from their surroundings, convert them and in some cases release them back to the atmosphere or utilize them to prime and/or activate defense mechanisms. Whether volatile signal perception is merely based on diffusion or, alternatively, on a biosensorial mechanism that involves receptors, transporters or vesicles is not clear and this knowledge will be crucial for our understanding of plant communication and interactions within ecosystems.
