Herbicide-resistant rice plants, polynucleotides encoding herbicide-resistant acetohydroxyacid synthase large subunit proteins, and methods of use

A viable non-transgenic rice seed, comprising:

• a mutagenized endogenous rice acetohydroxyacid synthase large subunit (AHASL1) polynucleotide having a sequence that encodes a herbicide-tolerant AHASL1 protein comprising the amino acid sequence of SEQ ID NO:2, SEQ ID NO:2 having a valine at position 179, wherein the polynucleotide is free of sited-directed mutations;
• and
• a phenotype of tolerance to 75 cc active ingredient/hectare (a.i./ha) imazapyr and 24.85 g a.i./ha imazapic as a result of the presence of the valine at position 179 of SEQ ID NO:2,
• wherein said sequence of the polynucleotide has been obtained by chemical mutagenesis using a chemical mutagen, and
• wherein said herbicide-tolerant AHASL1 protein further comprises at least one member selected from the group consisting of:
• (a) a threonine at amino acid position 96 of SEQ ID NO:2;
• (b) an alanine, threonine, histidine, leucine, arginine, isoleucine, glutamine, or serine at amino acid position 171 of SEQ ID NO:2;
• (c) a leucine at amino acid position 548 of SEQ ID NO:2;
• and
• (d) an asparagine, threonine, or phenylalanine at amino acid position 627 of SEQ ID NO:2.

A non-transgenic rice plant comprising:

• a mutagenized endogenous rice acetohydroxyacid synthase large subunit (AHASL1) polynucleotide having a sequence that encodes a herbicide-tolerant AHASL1 protein comprising the amino acid sequence of SEQ ID NO:2, SEQ ID NO:2 having a valine at position 179, wherein the polynucleotide is free of site-directed mutations;
• and
• a phenotype of tolerance to 75 cc active ingredient/hectare (a.i./ha) imazapyr and 24.85 g a.i./ha imazapic, as a result of the presence of the valine at position 179 of SEQ ID NO:2, wherein, as a result of said phenotype, said non-transgenic rice plant, if treated with 75 cc a.i./ha imazapyr and 24.85 g a.i./ha imazapic, either (a) does not exhibit any phytotoxic symptoms, or (b) is not killed or inhibited in its growth, or both (a) and (b), and
• wherein said sequence of the polynucleotide has been obtained by chemical mutagenesis using a chemical mutagen.