mykorrhizat

Mykorrhizat is a symbiotic association between a fungus and a plant root in which the fungus colonizes the root tissue or the surrounding soil space and contributes to the plant’s nutrient and water uptake in exchange for photosynthetically derived carbon. The relationship is widespread among land plants and is typically mutualistic, though the balance of benefits can vary with environmental conditions and partner identity.

Two principal forms are recognized: arbuscular mycorrhiza (AM), in which fungal hyphae penetrate root cortical cells and form arbuscules and vesicles; AM is widespread among herbaceous plants and many crops. Ectomycorrhiza (EM), by contrast, forms a sheath around the root tip and a network between root cells (the Hartig net) without entering the cytoplasm, and is common in many temperate and boreal trees such as pines, oaks, and beeches.

Other notable forms include ericoid mycorrhiza, which associates ericaceous plants, and orchid mycorrhiza, which is essential for many orchid seedlings. AM and EM fungi differ in taxonomy, anatomy, and the range of host plants.

Formation and signaling involve a plant–fungus dialogue. Root exudates such as strigolactones stimulate fungal growth, while fungi release signaling molecules (Myc factors) that promote colonization. In AM, arbuscules facilitate nutrient exchange within root cells; in EM, the Hartig net and mantle mediate exchange in the extracellular space.

Ecological and agricultural significance is substantial. Mycorrhizae enhance phosphorus and micronutrient uptake, improve water acquisition, influence soil structure through hyphal networks, and can bolster drought tolerance and disease resistance. They are exploited in sustainable agriculture and reforestation as inoculants to improve plant establishment.