Resistance to Acetohydroxyacid Synthase-Inhibiting Herbicides

Abstract

Nucleotide sequences are disclosed that may be used to impart herbicide resistance to green plants. The sources of novel herbicide resistance were originally isolated in mutant rice plants. The sequences impart pre-emergence resistance, post-emergence resistance, or both pre-emergence resistance and post-emergence resistance to multiple herbicides. To date, resistance has been demonstrated against at least the following herbicides: imazethapyr, imazapic, imazapyr, imazamox, sulfometuron methyl, imazaquin, chlorimuron ethyl, metsulfuron methyl, rimsulfuron, thifensulfuron methyl, pyrithiobac sodium, tribenuron methyl, and nicosulfuron. Green plants transformed with these sequences are resistant to these herbicides and to derivatives of these herbicides, and to at least some of the other herbicides that normally inhibit acetohydroxyacid synthase (AHAS), particularly imidazolinone and sulfonylurea herbicides.

What is claimed: 
     
         1 . An isolated, recombinant, mutagenized, or synthetic polynucleotide encoding an acetohydroxyacid synthase (AHAS) polypeptide, wherein the sequence of the encoded AHAS polypeptide has about 95% or greater sequence identity with SEQ ID NO:19, and wherein said polynucleotide is operatively linked to a heterologous promoter. 
     
     
         2 . The polynucleotide of  claim 1 , wherein said polynucleotide has about 95% or greater sequence identity with SEQ ID NO:18. 
     
     
         3 . A host cell comprising the polynucleotide of  claim 1 . 
     
     
         4 . A method for producing a plant having tolerance to a herbicide, said method comprising transforming plant cells with the polynucleotide of  claim 1 , wherein the plants cells are capable of regenerating a plant. 
     
     
         5 . A plant produced by the method of  claim 4 , wherein cells of said plant express the encoded AHAS polypeptide. 
     
     
         6 . A method for producing a herbicide-tolerant plant, said method comprising crossing or back-crossing the plant of  claim 5  with other germplasm to produce a progeny plant, wherein cells of said progeny plant express the encoded AHAS polypeptide. 
     
     
         7 . A plant produced by the method of  claim 6 , wherein cells of said herbicide-tolerant plant express the encoded AHAS polypeptide. 
     
     
         8 . A method for controlling weeds in the vicinity of the plant of  claim 5 , said method comprising applying a herbicide in the vicinity of the plant, at a level of the herbicide that would normally inhibit the growth of a wild-type plant of the same species, wherein the herbicide normally inhibits acetohydroxyacid synthase. 
     
     
         9 . The method of  claim 8 , wherein the herbicide comprises a herbicidally effective imidazolinone. 
     
     
         10 . The method of  claim 8 , wherein the herbicide is selected from the group consisting of imazethapyr, imazapic, imazapyr, imazamox, and imazaquin. 
     
     
         11 . The polynucleotide of  claim 1 , wherein the sequence of the encoded AHAS polypeptide comprises SEQ ID NO:19. 
     
     
         12 . The polynucleotide of  claim 11 , wherein the sequence of said polynucleotide is not SEQ ID NO:18. 
     
     
         13 . A rice plant, wherein the cells of said rice plant comprise the polynucleotide of  claim 11 . 
     
     
         14 . A seed of the rice plant of  claim 13 , or a seed capable of producing said rice plant, wherein cells of said seed comprise said polynucleotide. 
     
     
         15 . A method for controlling weeds in the vicinity of the plant of  claim 13 , said method comprising applying a herbicide in the vicinity of the plant, at a level of the herbicide that would normally inhibit the growth of a wild-type plant of the same species, wherein the herbicide normally inhibits acetohydroxyacid synthase. 
     
     
         16 . The method of  claim 15 , wherein the herbicide comprises a herbicidally effective imidazolinone. 
     
     
         17 . The method of  claim 15 , wherein the herbicide is selected from the group consisting of imazethapyr, imazapic, imazapyr, imazamox, and imazaquin. 
     
     
         18 . A rice plant, wherein the cells of said rice plant comprise the polynucleotide of  claim 1 . 
     
     
         19 . A herbicide-resistant rice plant, wherein said rice plant expresses an acetohydroxyacid synthase in which the amino acid is asparagine at the position equivalent to amino acid position 627 of SEQ ID NO:19. 
     
     
         20 . An isolated, recombinant, mutagenized, or synthetic rice acetohydroxyacid synthase (AHAS) polypeptide having:
 (a) about 95% or greater sequence identity with SEQ ID NO:19, wherein said AHAS polypeptide has an asparagine at the position equivalent to amino acid position 627 of SEQ ID NO:19; or   (b) about 95% or greater sequence identity with SEQ ID NO:25, wherein said AHAS polypeptide has a glutamic acid at the position equivalent to amino acid position 628 of SEQ ID NO:25.