Quito-lipo-oligosaccharides that stimulate arbuscular mycorrhizal symbiosis

A mixture of lipo-I chito-oligosaccharides defined by the following formula (I): ** Formula ** wherein said formula comprising: - a lipo-I chito-oligosaccharide of formula (I) wherein n> = 2, R1 represents a chain saturated fatty acid containing 16 carbon atoms and R2 represents H; - one lipo-chito-oligosaccharide I of formula (I) wherein n> = 2, R1 represents a chain saturated fatty acid containing 16 carbon atoms and R2 represents SO3H; - one lipo-chito-oligosaccharide I formula (I) wherein n> = 2, R1 represents a chain monounsaturated fatty acid containing 18 carbon atoms and R2 represents H; and - one lipo-chito-oligosaccharide of formula (I) wherein n> = 2, R1 represents a monounsaturated fatty acid chain containing 18 carbon atoms and R2 represents SO3H.