Authors: XiaoQi Zhang Stephen B Powles
Publish Date: 2005/08/23
Volume: 223, Issue: 3, Pages: 550-557
Abstract
AcetylCoA carboxylase ACCase EC6412 is an essential enzyme in fatty acid biosynthesis and in world agriculture commercial herbicides target this enzyme in plant species In nearly all grass species the plastidic ACCase is strongly inhibited by commercial ACCase inhibiting herbicides aryloxyphenoxypropionate APP and cyclohexanedione CHD herbicide chemicals Many ACCase herbicide resistant biotypes populations of L rigidum have evolved especially in Australia In many cases resistance to ACCase inhibiting herbicides is due to a resistant ACCase enzyme Two ACCase herbicide resistant L rigidum biotypes were studied to identify the molecular basis of ACCase inhibiting herbicide resistance The carboxyltransferase CT domain of the plastidic ACCase gene was amplified by PCR and sequenced Amino acid substitutions in the CT domain were identified by comparison of sequences from resistant and susceptible plants The amino acid residues Gln102 CAG codon and Ile127 ATA codon were substituted with a Glu residue GAG codon and Leu residue TTA codon respectively in both resistant biotypes Amino acid positions 102 and 127 within the fragment sequenced from L rigidum corresponded to amino acid residues 1756 and 1781 respectively in the A myosuroides full ACCase sequence Allelespecific PCR results further confirmed the mutations linked with resistance in these populations The IletoLeu substitution at position 1781 has been identified in other resistant grass species as endowing resistance to APP and CHD herbicides The GlntoGlu substitution at position 1756 has not previously been reported and its role in herbicide resistance remains to be established
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