An appraisal of arbuscular mycorrhiza-mediated augmentation in production of secondary metabolites in medicinal plants

Medicinal plants produce secondary metabolites, which have pharmaceutical efficacy in diverse diseases. Plant-derived secondary metabolites are utilized in different industrial sectors including pharmaceuticals, food, cosmetics, and agrochemical. Reportedly, 80% of the global population rely on medicinal plants for primary health care. The increasing commercial demand of secondary metabolites in recent years has, thus, led to the adoption of different strategies to improve secondary metabolite production in plants. Optimization of biological resources to enhance the productivity of plants is an important way to create sustainable bioeconomy for the 21st century. With a score of studies reporting the positive impact of arbuscular mycorrhizal fungi (AMF) on producing important secondary metabolites in medicinal plants, this article reviews the status quo of AMF-medicinal plant association. Furthermore, it critically discusses the influence of symbiotic association on plant primary metabolism, which ultimately regulates secondary metabolite production and accumulation. The review introduces the symbiotic association between AMF and medicinal plants, followed by a brief account of plant metabolites’ roles in establishing and maintaining the symbiosis. In continuation, the influence of AMF on different medicinally important secondary metabolites such as alkaloids, flavonoids, phenolics, and terpenoids are briefly discussed. Furthermore, the underlying mechanisms of AMF-mediated accumulation of secondary metabolites are discussed, including the plant’s response mechanism to AMF colonization encompassing the morphological, physiological, and molecular responses. In conclusion, the article emphasizes the prospects of mycorrhizal technology in sustainable cultivation practices of medicinal plants.