Fecha de publicación: 08/01/2025 Fuente: WIPO "tomato" A composition and method that can act on an arbuscular mycorrhizal fungus to promote colonization of the arbuscular mycorrhizal fungus in a plant and to facilitate its symbiosis with the plant are provided. Provided is a composition for promoting colonization of an arbuscular mycorrhizal fungus, the composition comprising as an active component a secoiridoid glycoside, iridoid glycoside, or a glycoside in which a 3,4-dihydropyran ring skeleton forms at position 2 an O-glycosidic bond to a glucopyranose, or dried remains or an extract of a Gentianaceae plant. A method for improving soil by adding the composition to the soil is also provided.