Primed to grow: a new role for green leaf volatiles in plant stress responses.

Green leaf volatiles (GLV) have been well described to prime plants against biotic and abiotic stresses resulting in an accelerated and/or enhanced protective response. Since investments in priming are considered to be minor, it has been assumed that costs for plants using this mechanism are negligible. By analyzing the costs of defense priming by GLV, we found that while initially growth rates of plants were reduced within the first hours after treatment, significantly increased growth rates were found at later time points. This primed growth response in maize seedlings differs from primed defense responses in that it also affects systemic parts of the plant and suggests a metabolic component to be involved in the regulation of this process.