Transgenic plants with improved growth and nitrogen use efficiency

1. A method for increasing growth, yield, nitrogen use efficiency, nitrogen transport, nitrogen stress tolerance, pathogen resistance, survival and/or nitrogen acquisition of a plant comprising introducing and expressing a nucleic acid construct encoding a nitrate transporter having a pH sensing motif comprising amino acid residues VYEAIHKI comprising a nucleic acid sequence as defined in SEQ ID No. 1 or a homolog thereof, operably linked to a regulatory sequence in a plant,

wherein if the nucleic acid sequence is as defined in SEQ ID No. 1, said plant is not rice,

and wherein growth, yield, nitrogen use efficiency, nitrogen transport, nitrogen stress tolerance, pathogen resistance, survival and/or nitrogen acquisition is increased in said plant as compared to a plant that does not contain and express said nucleic acid sequence.

2. A method according to claim 1 , wherein said regulatory sequence is a constitutive or strong promoter directing overexpression of said nucleic acid.

3. A method according to claim 2 , wherein said constitutive or strong promoter is selected from CaMV-35S, CaMV-35Somega, and Arabidopsis ubiquitin UBQ1.

4. A method according to claim 1 , wherein said regulatory sequence is a phloem specific promoter.

5. A method according to claim 4 , wherein said phloem specific promoter comprises a nucleic acid comprising SEQ ID No. 5.

6. A method for making a transgenic plant having increased growth, yield, nitrogen transport, nitrogen acquisition, nitrogen stress tolerance and/or nitrogen use efficiency comprising

introducing and expressing in a plant or plant cell a nucleic acid construct encoding a nitrate transporter having a pH sensing motif comprising amino acid residues VYEAIHKI comprising a nucleic acid sequence as defined in SEQ ID No. 1 or a homolog thereof, operably linked to a regulatory sequence,

wherein if the nucleic acid sequence is as defined in SEQ ID No. 1, said plant is not rice,

and wherein growth, yield, nitrogen transport, nitrogen acquisition, nitrogen stress tolerance and/or nitrogen use efficiency is increased in said transgenic plant as compared to a plant that does not contain and express said nucleic acid sequence.

7. A method according to claim 1 , wherein said plant is a crop plant or a biofuel plant or bioenergy crop, wherein the biofuel plant or bioenergy crop is selected from the group consisting of rape/canola, sugar cane, sweet sorghum, Panicum virgatum (switchgrass), linseed, lupin, willow, poplar, poplar hybrid, Miscanthus or gymnosperm, loblolly pine, maize, grass, clover, sanfoin, alfalfa, cotton, flax, pine, oak, poplar turf grass, snapdragon, petunia, rose, geranium, Nicotiana sp., African violet, begonia, chrysanthemum, geranium, Coleus spider plant, Dracaena and rubber plant.

8. A method according to claim 7 , wherein said crop plant is selected from maize, wheat, tobacco, oilseed rape, sorghum, soybean, potato, tomato, grape, barley, pea, bean, field bean, lettuce, cotton, sugar cane, sugar beet, broccoli or other vegetable brassicas or poplar.

9. A method according to claim 7 , wherein said plant is maize or soybean.

10. A method according to claim 1 , wherein said plant is maize or soybean and said homolog is from maize or soybean.

11. A plant obtained or obtainable from a method as defined in claim 10 .

12. A transgenic plant expressing a nucleic acid construct encoding a nitrate transporter having a pH sensing motif comprising amino acid residues VYEAIHKI comprising a nucleic acid sequence as defined in SEQ ID No. 1 or a homolog thereof, operably linked to a regulatory sequence,

wherein if the nucleic acid sequence is as defined in SEQ ID No. 1, said plant is not rice.

13. A plant according to claim 12 , wherein said regulatory sequence is a constitutive or strong promoter directing overexpression of said nucleic acid.

14. A plant according to claim 13 , wherein said constitutive promoter or strong promoter is selected from CaMV-35S, CaMV-35Somega, and Arabidopsis ubiquitin UBQ1.

15. A plant according to claim 12 , wherein said regulatory sequence is a phloem specific promoter.

16. A plant according to claim 15 , wherein said phloem specific promoter comprises a nucleic acid comprising SEQ ID No. 5.

17. A plant according to claim 12 , wherein said plant is a crop plant or a biofuel plant or bioenergy crop, wherein the biofuel plant or bioenergy crop is selected from the group consisting of rape/canola, sugar cane, sweet sorghum, Panicum virgatum (switchgrass), linseed, lupin, willow, poplar, poplar hybrid, Miscanthus or gymnosperm, loblolly pine, maize, grass, clover, sanfoin, alfalfa, cotton, flax, pine, oak, poplar turf grass, snapdragon, petunia, rose, geranium, Nicotiana sp., African violet, begonia, chrysanthemum, geranium, Coleus spider plant, Dracaena and rubber plant.

18. A plant according to claim 17 , wherein said crop plant is selected from maize, wheat, oilseed rape, tobacco, sorghum, soybean, potato, tomato, grape, barley, pea, bean, field bean, lettuce, cotton, sugar cane, sugar beet, broccoli or other vegetable brassicas or poplar.

19. A plant according to claim 12 , wherein said plant is maize or soybean.

20. A plant according to claim 12 , wherein said plant is maize or soybean and said homolog is from maize or soybean.

21. A method for regulating pH homeostasis or reducing/altering acidification in a plant comprising

introducing and expressing a nucleic acid construct comprising a nucleic acid sequence encoding a nitrate transporter having a pH sensing motif comprising amino acid residues VYEAIHKI comprising a nucleic acid as defined in SEQ ID No. 1, or a functional variant or a homolog thereof, operably linked to a regulatory sequence in a plant,

and wherein regulating pH homeostasis or reducing/altering acidification in said plant is improved as compared to a plant that does not express said nucleic acid construct.

22. A method according to claim 21 , wherein said plant is selected from maize, wheat, tobacco, oilseed rape, sorghum, soybean, potato, tomato, grape, barley, pea, bean, field bean, lettuce, cotton, sugar cane, sugar beet, broccoli or other vegetable brassicas or poplar.

23. A method according to claim 21 , wherein said plant is maize or soybean.

24. A method according to claim 21 , wherein said plant is maize or soybean and wherein said homolog is from maize or soybean.

25. A method according to claim 21 , wherein said regulatory sequence is a constitutive or strong promoter directing overexpression of said nucleic acid.

26. A method according to claim 21 , wherein said regulatory sequence is a constitutive or strong promoter selected from CaMV-35S, CaMV-35Somega, and Arabidopsis ubiquitin UBQ1.

27. A method according to claim 21 , wherein said regulatory sequence is a phloem specific promoter.

28. A method according to claim 21 , wherein said regulatory sequence is a phloem specific promoter comprising a nucleic acid comprising SEQ ID No. 5.

29. A method according to claim 1 , wherein said nucleic acid sequence is selected from the sequence as defined in SEQ ID No. 1 or a nucleic acid sequence that has at least 90% identity to SEQ ID No. 1.

30. A method according to claim 6 , wherein said nucleic acid sequence is selected from the sequence as defined in SEQ ID No. 1 or a nucleic acid sequence that has at least 90% identity to SEQ ID No. 1.

31. A plant according to claim 12 , wherein said nucleic acid sequence is selected from the sequence as defined in SEQ ID No. 1 or a nucleic acid sequence that has at least 90% identity to SEQ ID No. 1.

32. A method according to claim 21 , wherein said nucleic acid sequence is selected from the sequence as defined in SEQ ID No. 1 or a nucleic acid sequence that has at least 90% identity to SEQ ID No. 1.

33. A method according to claim 32 , wherein said plant is not rice.