What is mycorrhiza ?

The correct answer is option (2) -Symbiotic associations of fungus with roots of plants .

Mycorrhiza refers to the symbiotic association between fungi and the roots of plants. The word "mycorrhiza" is derived from the Greek words "myco," meaning fungus, and "rhiza," meaning root. This mutually beneficial relationship is crucial for the health and growth of many plant species.

The benefits of mycorrhizal associations for both the fungus and the plant include:

• Nutrient Exchange: The fungus enhances the plant's ability to absorb essential nutrients, such as phosphorus and nitrogen, from the soil. In return, the plant provides the fungus with carbohydrates produced through photosynthesis.
• Increased Water Absorption: Mycorrhizal hyphae extend into the surrounding soil, increasing the surface area for water absorption by the plant.
• Enhanced Resistance to Pathogens: Mycorrhizal associations can contribute to the plant's defense mechanisms against certain soil-borne pathogens.
• Improved Soil Structure: The fungal hyphae help bind soil particles together, contributing to soil structure and stability.

 Many members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development.