ALS Gene Mutations in Apera Spica-Venti Confer Broad-Range Resistance to Herbicides

Abstract

ALSGene Mutations inApera Spica-VentiConfer Broad-Range Resistance to HerbicidesSeveral biotypes of wind bentgrass in Poland have been identified as being resistant to acetolactate synthase (ALS) inhibitors. We screened these weeds with chlorsulfuron and performed a whole-plant bioassay with a range of doses based on these four herbicides: chlorsulfuron, sulfosulfuron, propoxycarbazone-sodium and mesosulfuron-methyl + iodosulfuron-methyl-sodium mixture. Ten biotypes, diverse in their levels of resistance, were submitted for molecular tests. PCR amplification and sequencing of als domains demonstrated numerous single nucleotide polymorphisms. Nine biotypes showed non-synonymous substitutions in codon Pro197, changing it to Ser or Thr. Mutation in Pro197conferred a high level of resistance to the tested herbicides. Analysis of four biotypes also revealed a substitution in the Ala122codon, changing it to Val. In one biotype this substitution was not accompanied by Pro197mutation and this biotype was resistant to chlorsulfuron and mesosulfuron + iodosulfuron, but not to sulfosulfuron or propoxycarbazone-sodium. Correspondence between mutations and levels of resistan ce to ALS inhibitors may support management of resistant weeds with the existing palette of herbicides.