Mycorrhizal symbiosis is a mutualistic association of plant roots and fungi that plays a major role in ecosystem function and diversification, as well as its stability and productivity. It also plays a key role in the biology and ecology of forest trees, affecting growth, water and nutrient absorption and protection against soil-borne pathogens. However, the mycorrhizal research in tropical and neotropical ecosystems remains largely unexplored despite its importance in tropical and neotropical ecosystems. These ecosystems represent more than 0.6% of the total land ecosystems and they have a crucial role in the Earth’s biogeochemical cycling and climate. Threats to tropical forest biodiversity should therefore encourage investigations and inventories of mycorrhizal diversity, function and ecology in tropical latitudes because they concern ecologically and economically important plant species. This Research Topic aims to provide an overview of the knowledge of mycorrhizal symbioses in tropical and neotropical ecosystems. For this Research Topic, we welcome articles that address the diversity, ecology and function of mycorrhiza associated with plants, the impacts of mycorrhiza on plant diversity and composition, the regeneration and dynamics of ecosystems, and biomass production in ecosystems.