Conferred Resistance to an Acetolactate Synthase-inhibiting Herbicide in Transgenic Tall Fescue (Festuca arundinacea Schreb.)

Herbicide-resistant turfgrass can be an efficient tool that will allow easier turf maintenance. Acetolactate synthase (ALS) is the first common enzyme in the biosynthetic pathways leading to the branched-chain amino acids, and amino acid substitutions in ALS have been known to confer resistance to ALS-inhibiting herbicides. A two-point mutated rice ALS gene [OsALS (dm)] has been shown to confer strong resistance to bispyribac-sodium (BS), an ALS-inhibiting herbicide. In this study, we introduced into turf-type tall fescue (Festuca arundinacea Schreb.) the OsALS (dm) gene by using Agrobacterium-mediated transformation for conferring herbicide resistance. Stable integration of the transgene was confirmed by Southern blot analysis. Transgenic and wild-type plants were sprayed on the leaves with herbicide containing BS; approximately half of the transgenic plants were unaffected by the treatment and showed resistance to the herbicide, whereas the wild-type plants died. ALS activity in the leaf tissue of transgenic-resistant plants incubated with BS was almost equivalent to that in wild-type plants without BS and was higher than in wild-type plants incubated with BS. These indicate that the transgenic-resistant plants actively produced OsALS (dm) protein under herbicide treatment. This is the first report of herbicide-resistant transgenic tall fescue after introduction of a mutated ALS gene.