Non-target-site resistance to ALS inhibitors in Myosotona quaticum L.

【摘要】：Water chickweed(Myosoton aquaticum L.),a widely spread broadleaf weed,has become increasingly troublesome to control in China wheat fields.Many water chickweed populations were characterized as resistant to ALS inhibitors due to target-site ALS mutations.In this study,an initial tribenuron resistance confirmation test identified a resistant population(HN10).However,ALS gene analysis indicated there were no known ALS inhibitor resistance endowing mutations in resistant individuals.A subpopulation(MR1) was generated in terms of its mechanisms of resistance and response to other herbicides.Whole-plant dose response experiments showed that MR1 had a low-level of resistance to tribenuron.DNA sequencing assays indicated no known ALS resistance mutations in R plants.ALS in vitro activity assays revealed no differences in enzyme sensitivity between S and R populations.while the use of malathion in combination with tribenuron caused MR1 to behave like the S population.The low-level,malathion-reversible resistance,together with a sensitive ALS,strongly suggested that non-target-site enhanced metabolism is the mechanism of resistance.