Joan Rothchild Hardin
How Do Plants Communicate with Each Other?
We may not think of plants as being at all social but it turns out they are. Scientists have discovered that plants communicate with each other and have some ingenious ways of doing it — through both the air and the soil. Botanists know that many trees do not grow well near members of their own species but didn’t know how they could tell which plants were growing nearby. A recent study found they are able to engage in plant-soil feedback and are reacting to soil-dwelling microorganisms near the trees’ roots. Other plants, such as sagebrush, prefer to grow near others of their kind. This allows them to communicate with their neighbors by sending out airborne chemicals from their foliage and branches that help them collectively fend off herbivores, such as caterpillars and grasshoppers. (Ross, 2011) The graphic below from The Scientist illustrates the various methods plants use for communicating with each other.
Since the text in the graphic will probably be too small for you to read unless you’ve got considerably better than 20/20 vision, here is what it says. The numbers refer to areas in the graphic: THE SECRET SOCIAL LIVES OF PLANTS “Contrary to the long-held idea that plants are uncommunicative, recent research had made it clear that many species conduct lively and informative conversations with one another. Scientists have revealed that plants communicate through the air, by releasing odorous chemicals called volatile organic compounds (VOCs), and through the soil, by secreting soluble chemicals into the rhizosphere and transporting them along thread-like networks formed by soil fungi. And this is more than mere gossip: these signals warn neighbors of the many dangers facing plants. “In response to herbivore attacks (1) or infection (2), plants release a blend of volatile organic compounds (VOCs) into the air (3). Neighboring plants respond by activating defense responses or altering expression of defense-related genes to prime themselves against impending stress (4). “Warning signals about herbivore damage and fungal pathogens are also transmitted via the filamentous hyphae of soil fungi that colonize and connect the roots of different plants in common mycelial networks (CMNs) (5). How compounds zip along these fungal networks is not clear, but researchers have hypothesized that they could travel along the thin layer of water flowing along the surface of the hyphae or through the cytoplasm of the hyphae themselves. “Plants stressed by drought (6) secrete soluble chemicals from their roots that diffuse through the soil to the roots of neighboring plants (7). Receiver plants respond not only by closing the stomata on their leaves (8), but also by relaying the message to other nearby plants (9).” (Cossins, 2013) This short video by plant ecologist Suzanne Simard presents her findings on how trees communicate with each other via underground fungal networks:
And, for those of you who want to know even more about how this underground communication among trees works, here’s a longer TED Talk Simard gave on How Trees Talk To Each Other | TED Talk | TED.com TED Talks – “A forest is much more than what you see,” says ecologist Suzanne Simard. Her 30 years of research in Canadian forests have led to an astounding discovery — trees talk, often and over vast distances. Learn more about the harmonious yet complicated social lives of trees and prepare to see the natural world with new eyes.
SYMBIOSIS BETWEEN MYCORRHIZAL FUNGI AND PLANTS Endomycorrhizal fungi on the left. Ectomycorrhizal fungi on the right
“If you have any interest in gardening or farming, there is another player in addition to the plants and soil that you should know about: mycorrhizal fungi. This type of fungus forms a symbiotic relationship with approximately 90% of plants! The fungi colonize the roots of the plant and then extend their hyphae far into the soil, bringing nutrients and water that would otherwise be out of reach to its host. In return, the plant provides the fungus with carbohydrates. “There are two types of mycorrhizal fungi …. endomycorrhizal fungi associate with many agricultural crops and ectomycorrhizal fungi mostly associate with trees. Endomycorrhizal fungi penetrate the plant roots cells, while ectomycorrhizal form a layer around the root. Ectomycorrhizal are classified by producing mushrooms above ground, which endomycorrhizal do not do. Some popular edible mushrooms, such as chanterelles and truffles, are ectomycorrhizal. The entire underground structure of the fungus is called the hyphal network….” (PermaculturePower.com, 1/31/2013) Other examples of plants communicating with each other: In 2010 Chinese researchers found that tomato plants infected with a leaf blight alerted nearby tomato plants, which then started activating genes that helped ward off the infection – even when all airflow between the plants had been eliminated. The researchers speculated, but could not prove, that molecules signalling danger were passing through an underground fungal network. (The Economist, 2013)
Following up on the Chinese finding, a Scottish researcher found that symbiotic fungi on the roots of bean plants (Vicia faba) acted as an underground signaling network, transmitting early warnings of impending aphid attacks. In an aphid attack, bean plants that were connected by a network of thread-like mycorrhizal mycelia (symbiotic fungal structures known to help gather more nutrients for the plants) released chemicals that repelled the insects and attracted parasitoids that eat aphids. (Cossins, 2013)
If you have more time and desire still more information on how and why plants communicate with each other, here’s an interesting 53 minute documentary called What Plants Talk About:
What Plants Talk About (Full Documentary) Published on Feb 28, 2014 “When we think about plants, we don’t often associate a term like ‘behavior’ with them, but experimental plant ecologist JC Cahill wants to change that. The University of Alberta professor maintains that plants do behave and lead anything but solitary and sedentary lives. What Plants Talk About teaches us all that plants are smarter and much more interactive than we thought!”
See The Soil’s Microbiome for more information on soil health and how genetically modified seeds are destroying the beneficial soil bacteria necessary for growing nutritious plants and seriously impacting the health of all creatures dependent on those plants — including ourselves.
REFERENCES Cossins, D. (2013). Plants Communicate with Help of Fungi. The Scientist. See http://www.the-scientist.com/?articles.view/articleNo/35542/title/Plants-Communicate-with-Help-of-Fungi/ PermaculturePower.com. (1/31/2013). (No title). See: https://permaculturepower.wordpress.com/tag/animals/ Ross, V. (2011). The Secret Social Lives of Plants. DiscoverMagazine.com. See http://discovermagazine.com/2010/nov/14-the-secret-social-life-of-plants#.UxqduOddXF8 The Economist. (2013). Beans’ talk: Vegetables employ fungi to carry messages between them. See http://www.economist.com/news/science-and-technology/21580443-vegetables-employ-fungi-carry-messages-between-them-beans-talk © Copyright 2016 Joan Rothchild Hardin. All Rights Reserved.
DISCLAIMER: Nothing on this site or blog is intended to provide medical advice, diagnosis or treatment.