Independent Evolution of Acetolactate Synthase-inhibiting Herbicide Resistance in Weedy Sorghum Populations across Common Geographic Regions

Traditional breeding has been used to develop grain sorghum germplasm that is tolerant to acetolactate synthase (ALS)-inhibiting herbicides (Inzen Technology, DuPont). Inzen sorghum carries a double mutation in the ALS gene (Val560Ile and Trp574Leu), which confers high level of tolerance to ALS-inhibiting herbicides. Overreliance on ALS-inhibiting herbicides for weed control during the 1990s resulted in the evolution of ALS inhibitor—resistant shattercane populations in Nebraska. According to a survey conducted in 2013, ALS inhibitor—resistant weedy Sorghum populations persist in Nebraska. The objectives of this research were to determine whether the ALS mutations present in Inzen sorghum were present in the ALS inhibitor—resistant shattercane and johnsongrass populations detected in Nebraska and northern Kansas, and whether these populations evolved ALS resistance independently. Primers specific to the Val560 and Trp574 region of the ALS gene were used to screen the populations with PCR. The Trp574Leu mu...