Arbuscular Mycorrhizal Fungi and Strigolactone: Role, Application, and Effects of Synthetic Strigolactone in Plant Growth Promotion

Arbuscular mycorrhizal fungi (AMF) are widely distributed soil-borne microbes that have a symbiotic relationship with almost 80% of all terrestrial plants. They play a significant role in the induction of plant growth and development, plant nutrient uptake, soil nutrient management, and management of biotic and abiotic stress. The detection and colonization of host plant roots by AMF are induced by secondary metabolites known as signaling molecules that are released by plants as root exudates. Strigolactones are a group of apocarotenoids that are well known to act as signaling compounds in the rhizosphere. They play a crucial role in spore germination and hyphal branching of AMF, which further induce the symbiosis between AMF and higher plants. In spite of being effective at extremely low concentrations, the bioavailability of natural strigolactones in the soil is limited by plant-regulated biosynthesis and release, susceptibility to hydrolytic and photodegradation, and low mobility in soil. These bottlenecks can be overcome with the introduction of synthetic strigolactone analogs that will open new dimensions in sustainable agriculture.