Mycorrhizae

Definition

Mycorrhizae are symbiotic associations between fungi and plant roots, playing a crucial role in enhancing nutrient and water uptake for plants. This partnership benefits both parties: fungi receive carbohydrates and other organic compounds from the plant, while plants gain improved access to essential nutrients such as phosphorus and nitrogen. These relationships are vital for the health of ecosystems, particularly in nutrient-poor soils.

5 Must Know Facts For Your Next Test

1. Mycorrhizae can improve soil structure by increasing aggregation, which enhances aeration and water retention.
2. Over 80% of terrestrial plants form mycorrhizal associations, indicating their widespread importance in ecosystems.
3. Mycorrhizal networks can connect multiple plants, allowing for nutrient sharing and communication between different species.
4. These fungal associations can protect plants from pathogens by outcompeting harmful microbes for space and resources.
5. The health of mycorrhizal relationships is often threatened by agricultural practices that disrupt soil ecosystems, such as tillage and excessive use of fertilizers.

Review Questions

• How do mycorrhizae enhance nutrient uptake in plants compared to plants without these associations?
  • Mycorrhizae significantly enhance nutrient uptake in plants by extending their root systems through fungal hyphae, which can reach areas of soil that plant roots cannot access. This increases the surface area for absorption, particularly for nutrients like phosphorus and nitrogen. In contrast, plants without mycorrhizal associations may struggle to acquire enough nutrients, especially in nutrient-poor soils, limiting their growth and overall health.
• Evaluate the ecological significance of mycorrhizal networks in maintaining healthy ecosystems.
  • Mycorrhizal networks play a critical role in ecosystem health by facilitating nutrient exchange among plants and enhancing their resilience to environmental stressors. These networks allow for interplant communication and support less competitive or weaker plants by sharing resources. This interconnectedness contributes to biodiversity and stability within ecosystems, making them more resistant to disturbances such as drought or disease.
• Analyze the potential impacts of agricultural practices on mycorrhizal relationships and soil health.
  • Agricultural practices like tillage and heavy fertilizer use can severely disrupt mycorrhizal relationships, leading to a decline in soil health and fertility. Tillage disturbs the soil structure and reduces fungal networks, while synthetic fertilizers can diminish the need for plants to engage with mycorrhizae by providing readily available nutrients. This disruption can result in poorer plant growth, reduced biodiversity, and increased vulnerability to pests and diseases, highlighting the importance of sustainable farming practices that support these beneficial relationships.

Related terms

Endomycorrhizae: A type of mycorrhizal association where fungi penetrate the cortical cells of the plant roots, forming structures called arbuscules and vesicles that facilitate nutrient exchange.

Ectomycorrhizae: A type of mycorrhizal association where fungi form a thick sheath around the outside of plant roots, enhancing water and nutrient absorption without penetrating root cells.

Rhizobia: Nitrogen-fixing bacteria that form symbiotic relationships with leguminous plants, helping them obtain nitrogen from the atmosphere in exchange for carbohydrates.