Characterisation of iodo- plus mesosulfuron resistance in an Alopecurus myosuroides Huds. Population from the Czech Republic

Abstract

The intensification of Alopecurus myosuroides Huds. (black-grass) is becoming a major problem due to its growing resistance to a broad spectrum of acetolactate synthase (ALS)-inhibiting herbicides. Hence, the present study was conducted to evaluate the resistance level of a black-grass population to iodosulfuron plus mesosulfuron and to identify the underlying resistance mechanism. Dose-response studies revealed that the resistance population is 22 times less sensitive to iodosulfuron plus mesosulfuron than the susceptible population. The probable resistance mechanism identified was the target-site substitution of proline (Pro) by threonine (Thr) at the 197th position of the ALS enzyme. Furthermore, whole plant response bioassay experiments demonstrated that this population is also resistant to pinoxaden, chlorotoluron, diflufenican plus pendimethalin plus chlorotoluron, fenoxaprop and flufenacet plus diflufenican. In summary, the current findings recommend using alternative herbicides in integrated weed management to interrupt the possible evolution of herbicide resistance in these species.

Keywords

• als-inhibitors resistance
• weed control
• molecular mechanisms
• pro197 mutations
• target-site resistance