Uncovering the Role of Mycorrhizal Fungi in Plant Nutrition

Mycorrhizal fungi are essential organisms that form a symbiotic relationship with plant roots. Colonizing the roots creates a vast network that enhances the plant’s ability to absorb nutrients and water from the soil, ultimately improving its overall health and growth. This mutualistic association is vital for the survival and prosperity of many plant species.

They Transfer Nutrients

Mycorrhizal fungi provide plants with water and nutrients they cannot access independently. They extend long, slender hyphae from their mycelia to the soil around plant roots. Although many are still unsure of the pronunciation of mycorrhizal, they recognize the importance of such fungi in plant nutrition.

According to experts, after a chemical interaction between the fungus and the plant, the hyphae pierce and invade the root surface to initiate mycorrhizal penetration. The hyphae absorb carbon (C) from roots in exchange for scavenged nutrients during this process.

Mycorrhizae also transfer nutrients, including nitrogen, phosphorous, and potassium, to the host plant. Recent work indicates that mycorrhizal fungi can even increase the availability of phosphorous and nitrogen in the soil to their host plants.

They Store Nutrients

Mycorrhizal fungi significantly enhance the nutrient uptake of plants, especially phosphorus. The extensive hyphal network of the fungi extends far beyond the reach of the plant roots, effectively scavenging for nutrients in the soil and delivering them to the plant. This mechanism improves the plant’s nutrient acquisition and contributes to the soil’s microbial ecology.

They Improve Soil Structure

Infection by ectomycorrhizal (EM) and endomycorrhizal (END) mycorrhizae increases root surface area and allows the plant to access water and nutrients from a larger soil volume. Mycorrhizae also help improve soil structure, prevent water stress and nutrient depletion, promote organic matter accumulation, reduce soil erosion, and provide resistance to biotic and abiotic stresses.

In a classic symbiotic mutualism, the plant sends sugars produced through photosynthesis to the mycorrhizal fungus as energy in exchange for a supply of limiting nutrients. Fungi then use these sugars as a carbon source to form their mycelial networks, improving soil aggregation and increasing nutrient availability.

Fungi also bind soil particles together, forming macroaggregates and eliminating spatial constraints on microaggregation. Like the role of roots, but at a much smaller scale, hyphae enmesh and entangle soil primary particles, organic materials, and small aggregates.

They Prevent Water Stress

There are thousands of species of mycorrhizal fungi that vary in their ability to form symbiotic relationships with different plant species. They are found in most terrestrial plants and 90% of crops.

Mycorrhizal fungi generally increase phosphorus and nitrogen nutrition to plants, but they also influence water absorption and disease resistance. Mycorrhizae can be divided into two types: ectomycorrhizae and endomycorrhizae. The former produces a sheath around the roots, while the latter produces hyphae inside the root cells and into the soil.

Studies have shown that mycorrhizal inoculation protects plants from water stress and increases osmolytes and antioxidants within the roots. It also affects redox signaling and hormonal responses at the cellular level, protecting plants from the detrimental effects of water stress.

They Break Down Rock

Mycorrhizal fungi extend long, threadlike structures called hyphae into the soil. These hyphae harvest water from pores too small for plant roots to enter and, in the process, increase the amount of water the plants can absorb. This symbiotic relationship helps prevent water stress, especially during dry periods.

The fungi also transport nutrients such as nitrogen, phosphorous, potassium, calcium, and zinc. They speed phosphorous uptake by converting rock phosphate into a more usable form. They also transport organic matter, such as humus and sand, into the root and pick up sugar from the plant.

The indispensable role of mycorrhizal fungi in plant nutrition cannot be overstated. The intricate interactions between these fungi and plant roots amplify nutrient uptake and immune defenses and bolster environmental adaptability. Embracing the inherent synergy between mycorrhizal fungi and plants holds immense promise for cultivating healthier and more resilient ecosystems.