The Role of Phytofungi in Enhancing The Quality of Active Compounds of Medicinal Plants in Polluted Environments

Medicinal and aromatic plants represent an important source of bioactive compounds that have various applications in medicine, pharmacy, and nutrition. However, their production is increasingly challenged by the rising problems with environmental pollution, poor soil fertility, and abiotic stresses that impinge negatively on the growth of the plant and its capacity for producing secondary compounds with therapeutic value. In such a scenario, symbiotic mycorrhizal fungi, particularly shrubby mycorrhizal fungi (AMF), have emerged as a potentially sustainable natural alternative capable of improving medicinal plant growth along with biochemical productivity both under optimum and stressful conditions. These fungi establish a network of hyphae beyond the root zone, thereby improving efficiency in the uptake of water and nutrients, especially phosphorus, iron, zinc, and trace elements, within the plant's rhizosphere. Generally, plants associated with AMF have greater resistance to drought and salinity and heavy metals due to the enhanced nutrient and water balance, induction of defense mechanisms, antioxidants, and better soil structuring through metabolites such as glomalin, which improves cohesion and stability in the soil. The effects of AMF extend to influencing secondary compound production, such as flavonoids, terpenoids, phenols, and alkaloids, through direct or indirect means, including increased biomass, enhanced photosynthesis, modulation of plant hormones, and induction of enzymes involved in biosynthetic pathways like PAL and CHS. A wide array of works reported on species like Salvia miltiorrhiza, Hypericum perforatum, and licorice presented that AMF inoculation positively and significantly enhances the active content, especially when multiple fungal species rather than a single one are used