Study

Volatile signaling in plant–plant interactions: "talking trees" in the genomics era

Baldwin, Ian T.; Halitschke, Rayko; Paschold, Anja; von Dahl, Caroline C.; Preston, Catherine A.

Science, 2006

Peer-reviewednarrative reviewmixed

What they did

A review of the evidence that plants respond to volatiles released by damaged neighbours, examining which effects survive field conditions, which are laboratory artefacts of enclosed air, and whether the interaction is better described as signalling or as eavesdropping.

Studied in: Nicotiana attenuata, Artemisia tridentata
Sample size: review of volatile-mediated plant interaction studies

What they found

Volatile-mediated priming of defences in neighbouring plants is real and demonstrated in the field, but effects fall off sharply with distance and depend on airflow. Whether emission is selected for its effect on neighbours, or neighbours have simply evolved to detect a cue, is not established by any of the evidence.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The interaction is better framed as eavesdropping on an unavoidable cue than as communication between plants, until evidence of selection on the emitter appears.

How NatureHQ reads it

The distinction this paper insists on is the one NatureHQ builds its plant pages around. A signal implies a sender that benefits from being understood; a cue is information that leaks whether or not anyone is listening. Damaged tissue smells damaged, and a neighbour that reacts to the smell has read a cue. Calling it talking imports a sender who has not been shown to exist.

Limitations

Effects measured mostly in a few well-studied systems, especially sagebrush and wild tobacco.
Enclosed laboratory air exaggerates concentrations far above field conditions.
The fitness benefit to the emitting plant, which the signalling interpretation requires, is the least well evidenced part.