Molecular basis of multiple resistance to ACCase-inhibiting and ALS-inhibiting herbicides in Lolium rigidum

• Published in: Weed research Vol. 47; no. 6; pp. 534 - 541
• Main Authors: TAN, M-K, PRESTON, C, WANG, G-X
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.12.2007; Blackwell Publishing Ltd; Blackwell Science
• Subjects: aryloxyphenoxypropionate; Biological and medical sciences; Chemical control; chlorsulfuron; cyclohexanedione; Fundamental and applied biological sciences. Psychology; gene; genes; imidazolinone; Lolium; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; point mutation resistance; ryegrass; sequence; sulfonylurea; Weeds; chlorsulfuron; sulfonylurea; Monocotyledones; Nitrogen heterocycle; Lyases; aryloxyphenoxypropionate; Lolium rigidum; Oxo-acid-lyases; Molecular parameter; point mutation resistance; Acetyl-CoA carboxylase; Gene; Gramineae; Ligases; Weed science; Multiple resistance; Angiospermae; imidazolinone; Inhibition; Organic compounds; Carbon-carbon ligases; Weed; Enzyme; cyclohexanedione; Pesticides; Enzyme inhibitor; Imidazolinone derivatives; ryegrass; Diazole; Herbicide; sequence; Carbon-carbon lyases; Point mutation; Sulfonylureas; Acetolactate synthase; Spermatophyta; Fodder crop; Nitrogen Organic compounds
• ISSN: 0043-1737; 1365-3180
• DOI: 10.1111/j.1365-3180.2007.00591.x

Herbicide resistance in Lolium rigidum is widespread across much of the agricultural land in Australia. As the incidence of herbicide resistance has increased, so has the incidence of multiple herbicide resistance. This reduces the herbicide options available for control of this weed. This study reports on the successful amplification and sequencing of the acetolactate synthase (ALS) gene of L. rigidum using primers designed from sequence information of related taxa. This enables, for the first time, the successful determination of a mutation in the ALS gene of this species that provides resistance to ALS-inhibiting herbicides. This mutation causes amino acid substitution at Trp574 (numbering standardised to Arabidopsis thaliana) to Leu which had been reported to confer a high level of resistance against all classes of ALS inhibitor herbicides. In addition, multiple resistance to ALS-inhibiting and acetyl-coenzyme A carboxylase-inhibiting herbicides is acquired through the independent accumulation of mutant alleles for the target sites. This may thus explain some of the irregular, mosaic resistance patterns that occur in this predominantly outcrossing species.