Transgenic plants synthesizing high amylose starch

1. A transgenic plant cell which has been genetically modified, the plant cell comprising:

a) in an antisense orientation relative to a promoter, a nucleic acid sequence of at least 500 nucleotides that hybridizes under high stringency conditions to a gene encoding an endogenous starch phosphorylase (R1) protein and that leads to the reduction, compared to the non-genetically modified plant cell, of the expression of one or more endogenous starch phosphorylase (R1) proteins;

b) in an antisense orientation relative to a promoter, a nucleic acid sequence of at least 500 nucleotides that hybridizes under high stringency conditions to a gene encoding an endogenous branching enzyme I (BEI) protein and that leads to the reduction, compared to the non-genetically modified plant cell, of the expression of one or more endogenous branching enzyme I (BEI) proteins; and

c) in an antisense orientation relative to a promoter, a nucleic acid sequence of at least 500 nucleotides that hybridizes under high stringency conditions to a gene encoding an endogenous branching enzyme II (BEII) protein and that leads to the reduction, compared to the non-genetically modified plant cell, of the expression of one or more endogenous branching enzyme II (BEII) proteins.

2. A transgenic plant cell comprising at least one nucleic acid molecule comprising:

a) a nucleic acid sequence comprising at least 500 nucleotides of a starch phosphorylase (R1) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a starch phosphorylase (R1) protein compared to expression in the non-transgenic plant cell;

b) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme I (BEI) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a branching enzyme I (BEI) protein compared to expression in the non-transgenic plant cell; and

c) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme II (BEII) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a branching enzyme II (BEII) protein compared to expression in the non-transgenic plant cell.

3. The transgenic plant cell according to claim 1 or 2 which synthesizes a modified starch.

4. The transgenic plant cell according to claim 3 , wherein the modified starch has an amylose content of at least 75% and a reduced phosphate content compared to starch from a non-transgenic plant cell.

5. The transgenic plant cell according to claim 3 , wherein the modified starch has a modified distribution of the side chains.

6. A transgenic plant comprising the transgenic plant cell according to claim 1 or 2 .

7. A method for producing a transgenic plant cell that synthesizes a modified starch, comprising the step of introducing into a plant cell at least one nucleic acid molecule, wherein said at least one nucleic acid molecule comprises:

a) a nucleic acid sequence comprising at least 500 nucleotides of a starch phosphorylase (R1) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a starch phosphorylase (R1) protein compared to expression in the non-transgenic plant cell;

b) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme I (BEI) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a branching enzyme I (BEI) protein compared to expression in the non-transgenic plant cell; and

c) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme II (BEII) gene operably linked to a promoter in an antisense orientation leading to reduced expression of an endogenous gene encoding a branching enzyme II (BEII) protein compared to expression in the non-transgenic plant cell;

thereby producing the transgenic plant cell that synthesizes a modified starch.

8. The method of claim 7 , wherein the modified starch has an amylose content of at least 75% and a reduced phosphate content in comparison with starch from a non-transgenic plant cell.

9. A method for producing a transgenic plant that synthesizes a modified starch comprising the step of

regenerating a plant from a plant cell produced according to the method of claim 7 ,

thereby producing the transgenic plant that synthesizes a modified starch.

10. The method according to claim 9 , wherein the modified starch has an amylose content of at least 75% and a reduced phosphate content in comparison with starch from a non-transgenic plant.

11. A transgenic plant obtained by the method according to claim 9 or 10 .

12. The transgenic plant according to claim 6 which is a starch-storing plant.

13. The transgenic plant according to claim 12 which is a potato plant.

14. Propagation material of the plant according to claim 6 , wherein the propagation material comprises the transgenic plant cell.

15. A nucleic acid molecule comprising:

a) a nucleic acid sequence comprising at least 500 nucleotides of a starch phosphorylase (R1) gene operably linked to a promoter in an antisense orientation, which when expressed in a plant cell leads to reduced expression of an endogenous gene encoding a starch phosphorylase (R1) protein compared to a the non-transformed plant cell;

b) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme I (BEI) gene operably linked to a promoter in an antisense orientation, which when expressed in a plant cell leads to reduced expression of an endogenous gene encoding a branching enzyme I (BEI) protein compared to the non-transformed plant cell; and

c) a nucleic acid sequence comprising at least 500 nucleotides of a branching enzyme II (BEII) gene operably linked to a promoter in an antisense orientation, which when expressed in a plant cell leads to reduced expression of an endogenous gene encoding a branching enzyme II (BEII) protein compared to the non-transformed plant cell.

16. A host cell comprising the nucleic acid molecule according to claim 15 .

17. The host cell according to claim 16 , wherein the cell is a plant cell.

18. The transgenic plant according to claim 11 which is a starch-storing plant.

19. The transgenic plant according to claim 18 which is a potato plant.

20. Propagation material of the plant according to claim 11 , wherein the propagation material comprises the transgenic plant cell.