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Plant Neighbors Transmit Airborne Warnings

November 17, 2000

Literally sensing danger in the air, some wild plants appear to boost their defenses against marauding insects when they receive a warning signal from a damaged neighbor plant, according to a study by UC Davis researchers.

"The results provide the strongest evidence to date that plants in the wild truly do communicate with each other," says entomology professor Richard Karban of the study that was published in a recent online edition of the journal Oecologia. "And it appears that this communication is transmitted through an airborne signal."

During three growing seasons spanning 1996 through 1998, Karban and colleagues monitored wild tobacco plants (Nicotiana attenuata) growing near sagebrush (Artemisia tridentata).

When experimentally clipped to mimic the effect of leaf-feeding caterpillars and grasshoppers, sagebrush plants emitted a volatile chemical known to trigger a defensive biochemical response in wild tobacco.

And, sure enough, the wild tobacco plants near the clipped sagebrush produced greater amounts of defensive enzymes in their leaves and suffered less damage from insects.

While it is clear that communication occurred between the plants, the UC Davis researchers say it remains to be seen whether either plant species ultimately benefits from the exchange of information.

The study was funded by the U.S. Department of Agriculture, the Max Planck Society and the National Science Foundation.

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