Lipochito-oligosaccharides stimulating arbuscular mycorrhizal symbiosis
The invention relates to lipochitooligosaccharides obtainable from arbuscular mycorrhizal fungi, and which are useful for stimulating arbuscular mycorrhizal symbiosis, and lateral root formation.
1. A method for stimulating mycorrhization of a plant which comprises contacting the plant, a part, a seedling or a seed thereof with a mixture of lipochitooligosaccharides consisting of a lipochitooligosaccharide defined by the formula (I):
wherein n=2, R 1 is a saturated or monounsaturated fatty acid chain containing 16 or 18 carbon atoms and R 2 is H; and
a lipochitooligosaccharide defined by the formula (I), wherein n=3, R 1 is a saturated or monounsaturated fatty acid chain containing 16 or 18 carbon atoms and R 2 is H.
2. The method of claim 1 , wherein said mixture of lipochitooligosaccharides consists of a lipochitooligosaccharide defined by the formula (I), wherein n is 2, R 1 is a saturated or monounsaturated fatty acid chain containing 16 carbon atoms and R 2 is H; and a lipochitooligosaccharide defined by the formula (I), wherein n is 3, R 1 is a saturated or monounsaturated fatty acid chain containing 16 carbon atoms, and R 2 is H.
3. The method of claim 1 , wherein said mixture of lipochitooligosaccharides consists of a lipochitooligosaccharide defined by the formula (I), wherein n is 2, R 1 is a saturated or monounsaturated fatty acid chain containing 18 carbon atoms and R 2 is H; and a lipochitooligosaccharide defined by the formula (I), wherein n is 3, R 1 is a saturated or monounsaturated fatty acid chain containing 18 carbon atoms, and R 2 is H.
4. The method of claim 1 , wherein said mixture of lipochitooligosaccharides is used at a concentration of 10 −5 to 10 −12 M.
5. A method for stimulating lateral root formation of a non-legume plant which comprises contacting said plant, a part, a seedling or a seed thereof with a mixture of lipochitooligosaccharides consisting of a lipochitooligosaccharide defined by the formula (I):
wherein n=2, R 1 is a saturated or monounsaturated fatty acid chain containing 16 or 18 carbon atoms and R 2 is H; and a lipochitooligosaccharide defined by the formula (I), wherein n=3, R 1 is a saturated or monounsaturated fatty acid chain containing 16 or 18 carbon atoms and R 2 is H.
6. The method of claim 5 , wherein said mixture of lipochitooligosaccharides consists of a lipochitooligosaccharide defined by the formula (I), wherein n is 2, R 1 is a saturated or monounsaturated fatty acid chain containing 16 carbon atoms and R 2 is H; and a lipochitooligosaccharide defined by the formula (I), wherein n is 3, R 1 is a saturated or monounsaturated fatty acid chain containing 16 carbon atoms and R 2 is H.
7. The method of claim 5 , wherein said mixture of lipochitooligosaccharides consists of a lipochitooligosaccharide defined by the formula (I), wherein n is 2, R 1 is a saturated or monounsaturated fatty acid chain containing 18 carbon atoms and R 2 is H SO 3 H, and a lipochitooligosaccharide defined by the formula (I), wherein n is 3, R 1 is a saturated or monounsaturated fatty acid chain containing 18 carbon atoms, and R 2 is H.
8. The method of claim 5 , wherein said mixture of lipochitooligosaccharides is used at a concentration of 10 −5 to 10 −12 M.