What we can learn from plants and their partners
Image courtesy of New Phytologist Trust, 33rd New Phytologist Symposium
Almost all plants around the world partner with tiny, miniscule creatures called mycorrhizal fungi. You might be most familiar with these fungi in the context of gourmet mushrooms like chanterelles or morels. Mushrooms, though, are just the fruiting bodies or reproductive organs of these fungi, popping up aboveground when fungi decide to spread their spores to reproduce. Beneath the soil, the actual body of the fungi consists of huge mats of small, thin, white threads that fuse tightly with plant roots. In fact, mycorrhizal is literally the combination of the Greek words mykos (fungi) and rhiza (root). In this fascinating partnership, mycorrhizal fungi either intertwine themselves around individual plant cells (called ectomycorrhizal) or penetrate the plant cell wall to form balloon-like structures within the plant cell called arbuscules (hence the name arbuscular mycorrhizal fungi given to this group). This tight connection exists because the plants and fungi each have something that the other does not. Plants use sunlight and photosynthesis to make sugars, which fungi need but cannot make themselves. Fungi, on the other hand, can spread through soil quickly when searching for food and transport these nutrients over long distances through their long, thin strands. This is something plant roots are not capable of doing, but plants need these nutrients to grow. Thus, plants give fungi sugar in return for nutrients, and both rely on the other to grow and survive.
But, how did this partnership begin? About 400 million years ago, plants began to make their way onto land from the oceans. Fossil evidence has shown that the first mycorrhizal fungi also appeared about 400 million years ago – almost at the exact same time as plants began colonizing land! This has led researchers to believe that this is no mere coincidence. In fact, it is now become increasingly accepted that fungi are what made it possible for the first plants to live on land. The theory states that, millions of years ago when the land was a harsh and stressful environment, soils were thin and scarce. By teaming up with fungi, plants could get access to the nutrients they needed in order to survive on land. Once plants established themselves on land, they changed the atmosphere by intaking huge amounts of carbon dioxide and increasing oxygen levels. This lowered the Earth’s temperature and allowed for the evolution of many new types of animals to create the world that we see today.
Recent research has shown that not only do plants partner with fungi, but these fungi allow plants to connect with other plants in vast, underground fungal networks. Plants use these networks to exchange food and water, and can even use these networks to warn each other of incoming danger and recognize and nurture family members. It is thought that these networks play a very important role in the ability of ecosystems to resist change, because they enable carbon storage and the re-distribution of nutrients throughout these networks. As our ecosystems face increasing pressures from climate change, it is important to better understand how these plant-fungal partnerships and emergent networks help maintain the health and resiliency of our ecosystems.
So, what can we learn from studying plants and their partners? Well, first of all, fungi are pretty cool! These tiny organisms, consisting of white threads that are barely visible to the naked eye, are part of what made our planet what it is today. But also, these relationships tell us that there are many things beyond what the eye can see, and we must look deeper and further to find the solutions that we seek. We can also learn that relationships are important, and by working together, we can achieve so much more. Also, don’t overlook the small things in life! And ultimately, there is so much we can learn from the natural world around us. After all, organisms like plants and fungi have had millions of years to evolve, facing problems and finding innovative solutions in order to keep surviving. By looking to those that have been around far longer than us, perhaps we can find answers to questions we never even thought to ask.
Anne Polyakov is a graduate student at the University of Washington and she studies how plants communicate using vast, underground fungal networks, through which they share nutrients and warning neighbors of incoming danger within the network. Anne studies the costs and benefits of participating in this network, and what we can learn from plant communities by listening to what they are saying in the wood wide web.