Effects of a plurality of mutations to improve herbicide resistance/tolerance in rice

Abstract

Rice is described that is tolerant/resistant to AHAS/ALS inhibitors because of a plurality of mutations that act synergistically in providing resistance/tolerance to the herbicide. Tolerance/resistance is due to presence of combined mutations in the rice leading to amino acid substitutions (A205V and G654E) in the AHAS/ALS enzyme. Use of the rice for weed control and methods of producing tolerant/resistant rice are also disclosed.

We claim: 
     
         1 . A monocot plant tolerant/resistant to AHAS/ALS inhibitors at levels significantly higher than those tolerated by plants without mutations in the amino acid sequence of the AHAS enzyme, and wherein the tolerance/resistance is associated with a plurality of nucleic acid sequence mutations leading to combined amino acid substitutions A205V and G654E in the AHAS/ALS enzyme, and wherein there is synergism in tolerance/resistance to the inhibitors associated with the combined substitutions. 
     
     
         2 . The monocot plant of  claim 1  is a rice plant. 
     
     
         3 . The rice plant of  claim 2  selected from plants produced by representative seeds deposited as ATCC accession numbers PTA-123859, PTA-123860 and PTA-123861, their progeny and derivatives. 
     
     
         4 . A rice plant tolerant/resistant to AHAS/ALS inhibitors, wherein the tolerance/resistance is associated with at least two nucleic acid sequences in the plant genome encoding amino acid substitutions in the AHAS/ALS enzyme, the substitutions selected from the group consisting of A205V, G654E, and combinations thereof. 
     
     
         5 . Seeds of the rice plant of  claim 2  deposited as ATCC accession numbers PTA-PTA-123859, PTA-123860 and PTA-123861. 
     
     
         6 . A method for controlling weeds in a rice field, the method comprising:
 a. having rice in the field wherein the rice is resistant to one or more AHAS/ALS inhibitors.   b. contacting the rice field with at least one of the herbicides to which the rice is resistant at levels known to kill weeds.   
     
     
         7 . The method of  claim 6 , wherein the rice is resistant to AHAS/ALS inhibiting herbicides, due to a synergistic effect caused by A205V and G654E amino acid substitutions in the enzyme. 
     
     
         8 . The method of  claim 7  wherein the plant is a rice plant. 
     
     
         9 . The AHAS/ALS inhibitors of  claim 1  comprising at least one imidazolinone herbicides. 
     
     
         10 . The imidazoline herbicide of  claim 9  selected from the group consisting of imazethapyr, imazamox, imazetopic, imazamethabenz, imazaquin, and combinations thereof. 
     
     
         11 . Progeny of the rice plant of  claim 1 . 
     
     
         12 . A method to produce a rice plant resistant to treatment with AHAS/ALS inhibitors at levels suitable for weed control, the method comprising combining a rice genome including a nucleic acid that effects a substitution of A205(179)V in the amino acid sequence of the AHAS/ALS enzyme, with a rice genome including a nucleic acid that encodes for a substitution of G654(628)E in the amino acid sequence of the AHAS/ALS enzyme.