Abstract
Arbuscular mycorrhizal fungi (AMF) that inhabit the rhizosphere and colonize plant roots are considered to be beneficial to plant growth. AMF improves the rhizosphere soil characteristics and assists host plants by supplying essential mineral nutrients, especially phosphorus, while inhibiting the translocation of toxic ions such as Na and other metals. Plants have several tolerance mechanisms for averting the negative effects of different environmental stresses they encounter. Among these mechanisms, the antioxidant system is the key tolerance tool and is supported by the accumulation of osmolytes and the selective absorption of ions. Many reports have been published on the potential of AMF in plant growth regulation. Most of the researchers have adhered to studying morphological changes in host plants and have rarely described the physiological, biochemical, and molecular mechanisms of AMF-induced growth promotion and stress tolerance. The present review explores the existing literature to report the current status of AMF research, with a special focus on the AMF-triggered changes in the antioxidant and osmolyte metabolisms of plants that ameliorate the negative effects of stresses. In addition, we identify some key potential future targets to enhance the understanding of the beneficial effects of AMF in plant growth improvement under normal and stress conditions.