Chemical communication in plants

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One way plants interact with various organisms in their environment to defend themselves and to reproduce is through chemical signals, among them volatile organic compounds (VOCs) or green leaf compounds (GLCs).

Chemical cues a defense mechanism

The saliva of insects triggers plants to release these chemical cues in order to attract the prey of that insect. For example, in a study lima bean plants infested with spider mites released chemicals that attracted another mite that preys on the spider mites. Other studies cite that plants will produce toxins, such as the tobacco plant with its nicotine, to kill the insect or slow down that insect’s ability to digest the plant.

A common cry for help we are familiar with is the smell of freshly cut grass: that’s the grass’ cry for help to indicate it’s injured. Researchers are still trying to understand why plants send chemical cues after an attack. One possibility includes that the release is not an adaptive behavior, but rather that the cues leak out as a consequence of the damage. The most recent research indicates that other neighboring plants also benefit from these chemical cues: to repel herbivores, attract predators of that herbivore, suppress germination of competitors, and communicate with other branches of the same plant and genetic relatives.

Chemical cues to reproduce

Besides visual cues, plants also use these VOCs to attract pollinators because some pollinators have limited vision. Other plants have developed odors to suggest something they are not, such as rotting meat or fecal matter, to attract specific insects.

Relevance to IslandWood

Chemical communication in plants is relevant at IslandWood because we teach students how to identify plants and teach the medicinal and cultural uses of plants, yet there is more to explore by taking a closer look at plant behavior and communication: interconnections, predator/prey/ally relationships, communication/communities, etc. At the bog, we point out the meat-eating plants; we could explore what chemical signals are involved in attracting insects to land on the meat-eating plants. In the garden scavenger hunt activity, we ask students to find a bee's lunchbox. We could explore in more depth how flowers attract bees. What chemical signals are involved in this flower-insect relationship?

Sources:

Karban, R., Shiojiri, K., Ishizaki, S. (2011) Pdf.png Plant communication – why should plants emit volatile cues? Journal of Plant Interactions6: 2-3, 81-84

Kwok, R. (2010) Message Undeliverable. Conservation Magazine

Bhanoo, S. (2010) From a Desert Plant, a Desperate Cry for Help. The New York Times

Shiestl, F.P. (2010) Pdf.png The evolution of floral scent and insect chemical communication. Ecology Letters. 13: 643-656

Karban, R. (2008) Pdf.png Plant behavior and communicationEcology Letters. 11: 727-739.

Russell, S.A. (2002) Talking Plants. Discover Magazine