title: Genetic basis, evolutionary origin and spread of resistance to herbicides inhibiting acetolactate synthase in common groundsel (Senecio vulgaris).
abstract: BACKGROUND
  Following control failure by herbicides inhibiting acetolactate synthase (ALS) in French wheat fields and vineyards, we aimed to confirm resistance evolution and investigate the evolutionary origin and spread of resistance in the tetraploid species Senecio vulgaris (common groundsel), a widespread, highly mobile weed.
  
  
  RESULTS
  Sequencing of two ALS homeologues in S. vulgaris enabled the first identification and characterisation of ALS-based resistance in this species. Cross-resistance patterns associated with Leu-197 and Ser-197 ALS1 were established using eight herbicides. Sequencing and genotyping showed that ALS-based resistance evolved by multiple, independent appearances of mutant ALS1 and ALS2 alleles followed by spread. Spread of a mutant ALS1 allele issued from one particular appearance event was observed over 60 km. Independent resistance appearance events and easy seed dispersion are the most likely reasons for populations of S. vulgaris containing different mutant ALS alleles. Accumulation of different alleles probably due to sexual reproduction was observed in the same plant.
  
  
  CONCLUSIONS
  Mutant ALS alleles and possibly other mechanisms cause resistance to ALS inhibitors in S. vulgaris. Management strategies should aim at limiting S. vulgaris establishment and seed set. Considering the mobility of this species, control coordination at a regional level is clearly necessary if resistance spread is to be contained.
authors.affiliation: INRA, UMR1347 Agroécologie, Dijon, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Délye
authors.affiliation: INRA, UMR1347 Agroécologie, Dijon, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Causse
authors.affiliation: INRA, UMR1347 Agroécologie, Dijon, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Michel
mesh_terms: D000095:Acetolactate Synthase / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D019143:Evolution, Molecular; D005602:France; D053209:Herbicide Resistance / Q000235:genetics; D006540:Herbicides / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012674:Senecio / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D006540:Herbicides; D010940:Plant Proteins; D000095:Acetolactate Synthase
keywords: Resistance; Senecio vulgaris (common groundsel); acetolactate synthase/acetohydroxy acid synthase; appearance; herbicide; spread