Atmospheric change and induced plant secondary metabolites - are we reshaping the building blocks of multi-trophic interactions?

At least for the foreseeable future, atmospheric concentrations of greenhouse gases - particularly carbon dioxide (CO2) and ozone (O3) - are projected to rise inexorably. Recent studies have begun to unveil the complex nature of how these gases modulate the expression of plant signaling hormones, the defensive chemistries produced, and the responses of the myriad trophic interactions involving plant pathogens as well as insect herbivores and their natural enemies. Given the ubiquity of complex trophic interactions in both natural and managed systems, it is crucial that we understand how CO2 and O3 interact with defense signaling hormones of plants and their consequences for their trophic associates if we are to adapt to, and even mitigate, the effects of climate change.