Comparison of different assay techniques used for detecting acetyl-CoA carboxylase (ACCase) and acetolactate synthase (ALS)-inhibitors herbicide resistance in sterile wild oat (Avena sterilis L.)

Intensive use of herbicides has resulted in the occurrence of herbicide resistance. Recently, herbicide resistance has become a global issue threatening agricultural food production. ACCase and ALS-inhibitor-resistant weeds constitute more than one-third of all the reported resistance cases worldwide becoming the main constraint to wheat production in Mediterranean environments. However, different techniques have been devised to detect herbicide resistance in weeds. This study was aimed to compare the reliability and validity of quick tests [filter paper and agar-based (seed and seedling)], greenhouse (whole-plant pot) and molecular tests for detecting the resistance to acetyl-CoA carboxylase (ACCase) and acetolactate synthase (ALS)-inhibiting herbicides in sterile wild oat (Avena sterilis L.) in Adana, Turkey. In the molecular test, ACCase genes of the resistance and susceptible populations were sequenced and compared. As a result, greenhouse tests confirmed that the resistant population of A. sterilis has a high-level of resistance to clodinafop-propargyl (11.97 fold) and pyroxsulam (42.88 fold); and low resistance level to pinoxaden (2.1 fold) and mesosulfuron-methyl+iodosulfuron-methyl-sodium (1.08 fold). The levels of resistance obtained from quick tests were less than 5-folds in all herbicides. Six mutation points "Serine (Ser), Glycine (Gly), Threonine (Thr), Valine (Val), Glutamine (Gln) and Phenylalanine (Phe)" were detected in the ACCase gene. In conclusion, the agar-based tests provided feasible, accurate, rapid and cost-effective herbicide resistance confirmations which need less space than a greenhouse and filter paper tests. The molecular test confirmed the target-site resistance in the resistant population. The study reports these mutations for the first time in A. sterilis in Turkey.