| abstract |
HPPD polypeptides and plants containing them are described that show full tolerance against one or more HPPD inhibitor herbicides belonging to various chemical classes. A set of mutant HPPD polypeptides are designed that do not have or only have a significantly reduced affinity to the HPPD inhibitor herbicides and, at the same time, the dissociation rate of the HPPD inhibitors of the mutant HPPD polypeptide increases to such an extent that HPPD inhibitors no longer act as slow binding or slow and strong binding inhibitors, but instead become completely reversible inhibitors. In particular, isolated polynucleotides encoding mutant HPPD polypeptides that grant tolerance to HPPD inhibitor herbicides belonging to different chemical classes are provided. Additionally, amino acid sequences corresponding to the polynucleotides are provided. Claim 1: A recombinant nucleic acid molecule encoding a 4-hydroxyphenylpyruvate dioxygenase (HPPD) polypeptide consisting of an amino acid sequence comprising (a) an alanine at the amino acid position corresponding to amino acid position 268 of the SEQ ID No. 1, (b) a proline at the amino acid position corresponding to amino acid position 335 of SEQ ID No. 1, (c) a histidine or aspartic acid at the position corresponding to amino acid position 336 of SEQ ID No. 1 and (d) a serine at the position corresponding to amino acid position 337 of SEQ ID No. 1 and where such HPPD polypeptide is tolerant of one or more HPPD inhibitor herbicides. |