It is hard to imagine something that cannot even be seen by the unaided eye being able to impact all life on earth in such a big way, and it might also seem farfetched that “fungus,” a term generally associated with a negative connotation, could be so drastically necessary for life, but mycorrhizal fungi do just that. They are specialized fungi that colonize plant roots and extend far into the soil, forming a symbiotic, mutually beneficial relationship with the plants it colonizes.
A fungus colonizing itself in the roots of the plants that we eat seems like a revolting concept at first, but mycorrhizal fungi form this symbiotic relationship with 90% of plant species in natural areas. They can really be thought of as an extension to the plants root system; they are usually more effective in absorbing nutrients for the plant than the plant’s own roots. These fungi can increase the surface absorption area of a plant from 100-1000 times. Another way they increase the absorption of nutrients is by releasing powerful enzymes into the soil that dissolve hard to capture nutrients the plants most likely would have missed out on. These fungi form an intricate web that captures and incorporates nutrients, which conserves nutrient capitol in the soil. Besides the increased absorption of water and nutrients, mycorrhizal fungi can also protect the plant from certain pathogens.
The benefits of this relationship go both ways; the plant provides sustenance for the fungi through supplying it with carbohydrates from photosynthesis. Associations with mycorrhizal are seen in the fossil record and these fungi are believed to be one of the contributing factors that allowed early land plants to conquer the land. Research has found that there are seven different types of mycorrhizal fungi, some extracellular (not penetrating the plants roots), and some intracellular (penetrating and entering the plants roots).
While mycorrhizal fungi are common in undisturbed soil, along with other beneficial soil organisms, many processes such as tillage, removal of topsoil, erosion, site preparations, and removal of weeds, have shown that they diminish the population of mycorrhizal fungi in soil. These techniques are often used in farming, and the diminishing colonization of these fungi have caused a number of companies to actually start selling products that reintroduce these mycorrhizal fungi into the soil, so they are there to aid the plant in absorbing that most nutrients possible.
So having fungi in the plants we eat is not only not harmful, it is advantageous! So much so that people pay money to put the fungi into the soil, and try to avoid losing these valuable fungi.