Abstract: A lignin derivative including a unit of general formula (I): in which R1, R2, R3 and R4, which may be identical or different, each represent a hydrogen atom, a methoxy group —OMe, a hydroxyl group, where appropriate protected by a protective group of a hydroxyl function, or a unit R5 represents a hydrogen atom, a protective group of a hydroxyl function or a unit; A represents an oxygen atom, a sulfur atom, an —NH group or an —NR? group; and R?1, R?2, R?3 and R?4 each represent a hydrogen atom or a substituent not including a mesomeric-effect electron-withdrawing group conjugated to the aromatic ring, a substituent from R?1, R?2, R?3 and R?4 representing the covalent bond with the benzylic carbon.

Abstract: The invention relates to lipochitooligosaccharides obtainable from arbuscular mycorrhizal fungi, and which are useful for stimulating arbuscular mycorrhizal symbiosis, and lateral root formation.