Arbuscular mycorrhizal fungi are biotrophic fungi that form an association with plant roots and render benefits in nutrient uptake, disease control and plant tolerance to stress conditions. Plant–mycorrhizal fungi interaction has been proposed as a suitable tool for contributing to sustainable agriculture and reducing the dependence on agrochemicals. Interactions between plants and arbuscular mycorrhizal fungi are regulated by several factors ranging from host traits to environmental conditions that affect the species richness, diversity and functions. In this review, we highlight recent advances on how host traits and environmental conditions in farming systems and/or in natural ecosystems affect the richness, physiology and ecological functions of arbuscular mycorrhizal fungi while specifying the gaps that need to be filled through research.