There is a fungus among us!

For over four hundred million years, arbuscular mycorrhizal fungi have been forming symbiotic relationships with plants around the globe. Found on almost every continent and in approximately 80% of vascular plants, these important fungi play a pivotal role in plant nutrient uptake in diverse ecosystems.

These important fungi begin their life in the soil – in the area where roots can grow. Plants release hormones that helps the fungi grow. The plants release the hormones to increase the chance of a root-fungi interaction.

Plants seek to interact with arbuscular mycorrhizal fungi to create a mutually beneficial relationship. Once the fungi and plant roots meet, the fungi penetrate the root cells. From there, the fungi create and establish incredible structures called arbuscules, which were named for their tree-like structure.

arbuscular mycorrhizal fungi within a cotton root sample under microscope. plants and fungus have mutually beneficial relationships
Image of arbuscular mycorrhizal fungi within a cotton root sample under optical microscope (160X magnification). The balloon-like structures are called vesicles. Vesicles are arbuscular mycorrhizal fungi’s storage structures. The lines extending from the vesicles are the hyphae of the arbuscular mycorrhizal fungi. Credit: Hayley Crowell

Due to their many branches, arbuscules have a high surface area. This allows the fungi to efficiently exchange many different nutrients with the plant. Arbuscular mycorrhizal fungi are known for increasing uptake of phosphorous in the plants they interact with. They can also provide greater uptake of nitrogen, potassium, zinc, and more.

In exchange, the host plant provides food to arbuscular mycorrhizal fungi. The plant shares products it makes during photosynthesis, like lipids and sugars. Arbuscular mycorrhizal fungi rely on the host plant for life, but it is a small price to pay for the plant to have greater access to essential nutrients.

Meanwhile, in the soil, arbuscular mycorrhizal fungi form an extensive network of hyphae. The branched hyphal system acts as an extension of the root system. This provides greater access to nutrients that would have otherwise been out of reach. This longer, extensive hyphal system can reach into soil pores that were previously too small for the root system to explore.

lab bench with dye, microscope slides, matches, tweezers and other lab equipment
Lab bench showing dye, lower left, used to stain root samples collected in the field. Sections of the root samples are then placed on microscope slides, upper right, for analysis. Credit: Hayley Crowell

Although arbuscular mycorrhizal fungi are small, they are mighty! One gram of soil can contain between one to twenty meters of hyphae. The microscopic fungi can dramatically improve nutrient uptake for its host plant. It is incredible what these fungi do for plants and, subsequently, humans.

Many researchers are exploring arbuscular mycorrhizal fungi’s role in agriculture. Important crops around the world, such as wheat, rice, corn, potato, cotton, and soybean, can form relationships with them. Finding ways to use the fungi’s impressive abilities could enable producers to meet the growing demand for food in an environmentally friendly way.

three people in cotton field collecting soil and root samples to analyze fungus colonization
Hayley Crowell, Anna Yang, and others carefully collect cotton root samples to analyze arbuscular mycorrhizal fungi colonization rates. Credit: Audrey Gamble

Sometimes referred to as “living fertilizers,” arbuscular mycorrhizal fungi have the potential to maintain yield while reducing some need for fertilizer. These fungi boost nutrient and water uptake. They can enhance soil structure. They even have been shown to improve plant responses stresses, such as soil salinization, heavy metal contamination, and extreme temperatures.

With the known benefits, it’s no surprise that researchers are looking to further understand how to protect and take advantage of these powerful, ancient fungi to improve crop productivity in degraded soils and a changing climate.

Answered by Hayley Crowell, Auburn University

To read another blog about soil fungi, read Do Plants and Soil Really Talk.

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6 thoughts on “There is a fungus among us!

  1. Do we know to what extent crop fungicide applications, specifically later season corn treatments, affect arbuscular mycorrhizal fungi?

    1. Hi Matt, thanks for this question. It’s beyond the scope of our blog (for the general public) but we encourage you to reach out to your local extension for this answer. SVF

    2. Hello,
      I have to say I am quite surprised and disappointed to see such a reply. I do not think the general public gives a hoot about arbuscular mycorrhizal fungi, and not to discredit my local extension, but they cannot cannot spell mycorrhizal much less care.

      1. Hi Matt, we’re sorry that we cannot give you an answer. Our research shows that gardeners and hobbyists truly do care about all life in soil, including mycorrhizal fungi, and “life in soil” is one of our biggest read topics. While we do admit both arbuscular and mycorrhizal are hard to spell, they are worth learning. We work with our bloggers to edit the blogs to the 8-10th grade reading level to make our science relatable to all levels…and this one is at 10th grade (average reading level of a college graduate). Please use the “contact us” button on our blog if you would like more information – we may be able to connect you with a soil scientist for your specific question. SVF

  2. If we looked at this from the point of view of the fungi, might we say that the fungi have found a way to “raise crops” to supply them with the carbon (sugar) they need to live?

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