MUTATED HYDROXYPHENYLPYRUVATE DIOXYGENASE, DNA SEQUENCE AND ISOLATION OF PLANTS WHICH ARE TOLERANT TO HPPD INHIBITOR HERBICIDES
The present invention relates to a nucleic acid sequence encoding a mutated hydroxyphenylpyruvate dioxygenase (HPPD), to a chimeric gene which comprises this sequence as the coding sequence, and to its use for obtaining plants which are resistant to HPPD inhibitor herbicides.
1 . A mutated hydroxyphenylpyruvate dioxygenase (HPPD) which retains its properties of catalysing the conversion of para-hydroxyphenylpyruvate (HPP) to homogentisate and which is less sensitive to a HPPD inhibitor than the original unmutated HPPD, characterized in that it contains a mutation on the amino acid glycine in position 336 with reference to the amino acid sequence of the Pseudomonas HPPD of SEQ ID NO:2 which is selected from the following group: Gly336His, Gly336Met, Gly336Phe, and Gly336Cys, provided that when the mutation is Gly336His, the amino acid at position 334 with reference to the amino acid sequence of the Pseudomonas HPPD of SEQ ID NO:2 is Gly.
2 . The mutated HPPD according to claim 1 , characterized in that the mutated HPPD contains a second mutation.
3 . The mutated HPPD according to claim 2 , characterized in that the second mutated amino acid is selected from the selected amino acids: Pro215, Gly298, Gly332, Phe333, Gly334 and Asn337, with reference to the Pseudomonas HPPD sequence of SEQ ID NO:2.
4 . A nucleic acid sequence which encodes a mutated HPPD according to claim 1 .
5 . A chimeric gene which comprises a coding sequence as well as heterologous regulatory element in the 5′ and optionally in the 3′ positions, which are able to function in a host organism, characterized in that the coding sequence contains at least a nucleic acid sequence according to claim 4 .
6 . The chimeric gene according to claim 5 characterized in that it contains in the 5′ position of the nucleic acid sequence which encodes a mutated HPPD, a nucleic acid sequence which encodes a plant transit peptide, with this sequence being arranged between the promoter region and the sequence encoding the mutated HPPD so as to permit expression of a transit peptide/mutated HPPD fusion protein.
7 . A transit peptide/mutated HPPD fusion protein, with the mutated HPPD being defined according to claim 1 .
8 . A cloning and/or expression vector for transforming a host organism, characterized in that it contains at least one chimeric gene according to claim 5 .
9 . A plant cell, characterized in that it contains at least a nucleic acid sequence according to claim 4 .
10 . The plant cell according to claim 9 characterized in that it contains, in addition, a gene that is functional in plants allowing overexpression of a PDH (prephenate dehydrogenase) enzyme.
11 . A transformed plant, characterized in that it contains a transformed plant cell according to claim 9 .
12 . A transformed seed, characterized in that it contains a transformed plant cell according to claim 9 .
13 . A method for obtaining a plant resistant to a HPDD inhibitor, characterized in that the plant is transformed with a chimeric gene according to claim 5 .
14 . A method for obtaining a plant resistant to a HPDD inhibitor according to claim 13 , characterized in that the plant is further transformed, simultaneously or successively, with a second gene functional in this plant allowing overexpression of a PDH (prephenate dehydrogenase) enzyme.
15 . A method for controlling weeds in an area or a field which contains transformed seeds according to claim 12 , which method comprises applying, to the said area of the field, a dose of a HPPD inhibitor herbicide which is toxic for the said weeds, without significantly affecting said seeds.
16 . A method for obtaining oil or meal comprising growing a transformed plant according to claim 11 , optionally treating such plant with an HPPD inhibitor herbicide, harvesting the grains and milling the grains to make meal and optionally extract the oil.
17 . The method according to claim 13 , in which the HPPD inhibitor is a triketone HPPD inhibitor.
18 . The method according to claim 17 , in which the HPPD inhibitor is selected from tembotrione, mesotrione, and sulcotrione.
19 . The mutated HPPD according to claim 1 , characterized in that the mutation on the amino acid glycine in position 336 is Gly336His.
20 . The mutated HPPD according to claim 1 , characterized in that the mutation on the amino acid glycine in position 336 is Gly336Met.
21 . The mutated HPPD according to claim 1 , characterized in that the mutation on the amino acid glycine in position 336 is Gly336Phe.
22 . The mutated HPPD according to claim 1 , characterized in that the mutation on the amino acid glycine in position 336 is Gly336Cys.