Volatile-mediated plant-plant interactions: VOCs as modulators of receiver plant defence, growth and reproduction.

It is firmly established that plants respond to biotic and abiotic stimuli by emitting volatile organic compounds (VOCs). These VOCs provide information on the physiological status of the emitter plant and are available for detection by the whole community. In the context of plant-plant interactions, research has focused mostly on defence-related responses of receiver plants. However, responses may span hormone signalling, both primary and secondary metabolism and ultimately affect plant fitness. Here we present a synthesis of plant-plant interactions focusing on the effects of VOC exposure on receiver plants. An overview of the important chemical cues, uptake and conversion of VOCs and the adsorption of VOCs to plant surfaces is presented. This is followed by review of the substantial VOC-induced changes to receiver plants affecting both primary and secondary metabolism and influencing plant growth and reproduction. Further research should consider whole plant responses for effective evaluation of mechanisms and fitness consequences of receiver plant exposure to VOCs.