University of California at Davis professor Richard Karban has published his most recent research in the latest edition of Ecology Letters. His research has shown that plants can warn nearby “clones,” or genetically identical cuttings, of forthcoming danger.

Karban’s group found that the sagebrush emits volatile cues when danger is imminent. For example, when a grasshopper comes close, the sagebrush signals to other branches, resulting in the production of chemicals that deter the curious herbivore.

Surprisingly, the plant produced the volatile chemical before physical contact with the herbivore occurred. This phenomenon has been widely observed in animals, such as skunks, but never in a plant.

Karban explained that “plants not only respond to reliable cues in their environments but also produce cues that communicate with other plants and with other organisms, such as pollinators, seed disperses, herbivores and enemies of those herbivores.”

The study also demonstrated that plants located within sixty centimeters of an experimentally clipped plant show less leaf damage than plants near an uncut neighbor. In other words, plants become more resistant to herbivores when their neighbor is damaged.

Additional experiments showed that the herbivores were not repelled by cues released by a clipped plant, but were repelled by the neighboring plants, emphasizing the idea that warning cues were sent from the damaged plant to its neighbors.

Discussion Question: How do you think the signals are sent from one plant to the other?

News Article: http://www.sciencedaily.com/releases/2009/06/090619171244.htm

Scientific Article: http://www3.interscience.wiley.com/journal/122352013/abstract?CRETRY=1&SRETRY=0