What role do mycorrhizae play in plant nutrition?

Mycorrhizae are symbiotic associations between fungi and plant roots that play a vital role in enhancing plant nutrition. These fungal partners extend the root system's reach through their hyphae, which are fine, thread-like structures. This expansion significantly increases the surface area available for nutrient absorption, particularly for essential nutrients like phosphorus, nitrogen, and certain micronutrients that are often limited in soil.

In addition to facilitating nutrient uptake, mycorrhizae assist plants in accessing water more effectively. The presence of mycorrhizae can improve a plant's growth and survival in nutrient-poor environments, making this symbiotic relationship crucial for plant health and productivity. Thus, the enhancement of nutrient uptake is the key function of mycorrhizae in plant nutrition, explaining why this option is the correct choice.