Weak and strong target site ALS resistance mutations in Raphanus raphanistrum: correlation between resistance at the ALS and plant level

GARCIA FEDERICO; GUNDEL PEDRO; GIL MERCEDES; VILA-AIUB MARTIN; NESTARES, GRACIELA

Harpenden, Hertfordshire

Conferencia; 8th International Meeting on Pesticide Resistance; 2019

Rothamsted Research

Despite the largely known effect of target site ALS resistance mutations in endowing plant survival under treatment of ALS inhibiting herbicides in many weeds, it remains unknown whether plants with these resistance mutations can reproduce similarly to an environment without ALS treatment. The resistance level of Raphanus raphanistrum (wild radish) with either the homozygous Ala-122-Tyr or Asp-376-Glu resistance mutations growing under chlorsulfuron treatment in a wheat crop was evaluated. The resistance level was estimated at both the plant and enzyme (ALS activity) scales. Results showed a similar level of survival in plants exhibiting either of the mutations and a positive correlation between ALS activity and fecundity under chlorsulfuron treatment. Plants with the Ala-122-Tyr mutation showed higher ALS activity and siliques mass than plants with the Asp-376-Glu mutation. Plants with the Ala-122-Tyr mutation showed no reduction in the mass of siliques produced under chlorsulfuron herbicide and wheat competition compared to the control treatment (no chlorsulfuron, no wheat). However, plants with the Asp-376-Glu mutation significantly reduced the reproductive output under herbicide and wheat competition compared to an environment with no herbicide and crop. The observed results enable to rank these ALS mutations in wild radish as ecologically strong (Ala-122-Tyr) and weak (Asp-376-Glu).