Novel targets for herbicides and transgenic plants resistant to said herbicides

Abstract

The invention concerns novel enzymes having an arogenate dehydrogenase activity, in particular arogenate dehydrogenase enzymes of plants, and the genes encoding said enzymes. The inventive arogenate dehydrogenase enzymes catalyze the last stage of the metabolic pathway of tyrosine biosynthesis, and constitute, as such, potential targets of herbicides. Hence the invention also concerns a method for identifying herbicide compounds targeting said enzymes, said herbicide compounds preventing tyrosine biosynthesis by being fixed on said enzymes. The invention further concerns transgenic plants tolerant to herbicide compounds targeting an enzyme involved in the tyrosine biosynthesis pathway, in particular an enzyme involved in the transformation of L-tyrosine prephenate, in particular an arogenate dehydrogenase enzyme. Said plants become tolerant by expression in their tissues of a prephenate dehydrogenase enzyme, said enzyme being insensitive to said herbicide compounds and enabling the plant to synthetize tyrosine despite being treated with said herbicide compounds.

1 - 36 . (canceled) 
     
     
         37 . A plant tolerant with respect to a herbicidal compound having as a target an enzyme involved in one of the metabolic steps for conversion of prephenate to L-tyrosine, characterized in that it contains a gene encoding a prephenate dehydrogenase enzyme and expresses said enzyme in its tissues. 
     
     
         38 . The plant as claimed in  claim 37 , characterized in that it is tolerant with respect to a herbicidal compound having as a target an arogenate dehydrogenase enzyme. 
     
     
         39 . (canceled) 
     
     
         40 . The plant as claimed in  claim 37 , characterized in that it is tolerant with respect to a herbicidal compound having as a target a prephenate aminotransferase enzyme. 
     
     
         41 . The tolerant plant as claimed in  claim 37 , characterized in that the gene encoding a prephenate dehydrogenase enzyme is a yeast gene. 
     
     
         42 . The tolerant plant as claimed in  claim 41 , characterized in that the gene encoding a prephenate dehydrogenase enzyme originates from a yeast of the  Saccharomyces  genus. 
     
     
         43 . The tolerant plant as claimed in  claim 42 , characterized in that the gene encoding a prephenate dehydrogenase enzyme is represented by the sequence identifier SEQ ID NO: 14. 
     
     
         44 . The tolerant plant as claimed in  claim 37 , characterized in that the gene encoding a prephenate dehydrogenase enzyme originates from a bacterium. 
     
     
         45 . The tolerant plant as claimed in  claim 44 , characterized in that the gene encoding a prephenate dehydrogenase enzyme originates from a bacterium of the  Bacillus  genus. 
     
     
         46 . The tolerant plant as claimed in  claim 45 , characterized in that the gene encoding a prephenate dehydrogenase enzyme is represented by the sequence identifier SEQ ID NO: 16. 
     
     
         47 . The tolerant plant as claimed in  claim 44 , characterized in that the gene encoding a prephenate dehydrogenase enzyme originates from a bacterium of the  Escherichia  genus. 
     
     
         48 . The tolerant plant as claimed in  claim 47 , characterized in that the gene encoding a prephenate dehydrogenase enzyme is represented by the sequence identifier SEQ ID NO: 18. 
     
     
         49 . The tolerant plant as claimed in  claim 44 , characterized in that the gene encoding a prephenate dehydrogenase enzyme originates from a bacterium of the  Erwinia  genus. 
     
     
         50 . The tolerant plant as claimed in  claim 49 , characterized in that the gene encoding a prephenate dehydrogenase enzyme is represented by the sequence identifier SEQ ID NO: 20. 
     
     
         51 . A method for producing plants tolerant with respect to herbidical compounds having as a target an enzyme involved in one of the metabolic steps for conversion of prephenate to L-tyrosine, comprising transforming a plant with a gene encoding a prephenate dehydrogenase enzyme in such a way that the transformed plant expresses said gene encoding a prephenate dehydrogenase in its tissues. 
     
     
         52 . The method as claimed in  claim 51 , characterized in that it applies to the production of plants tolerant with respect to herbicidal compounds having as a target the arogenate dehydrogenase enzyme. 
     
     
         53 . The method as claimed in  claim 51 , characterized in that it applies to the production of plants tolerant with respect to herbicidal compounds having as a target the prephenate aminotransferase enzyme. 
     
     
         54 . The method as claimed in  claim 51 , characterized in that the prephenate dehydrogenase enzyme originates from a yeast. 
     
     
         55 . The method as claimed in  claim 51 , characterized in that the prephenate dehydrogenase enzyme originates from a fungus. 
     
     
         56 . The method as claimed in  claim 51 , characterized in that the prephenate dehydrogenase enzyme originates from a bacterium. 
     
     
         57 . The tolerant plant as claimed in  claim 37 , characterized in that it further contains, in addition to a chimeric gene comprising, functionally linked to one another, at least: (a) one promoter which is functional in a host organism; (b) a polynucleotide encoding an enzyme having arogenate dehydrogenase activity; and (c) a terminator element which is functional in a host organism, and at least one other gene containing a polynucleotide encoding a protein of interest with respect to a herbicidal compound having as a target an enzyme involved in one of the metabolic steps for conversion of prephenate to L-tyrosine.