Genetic Transformation of Elite Turf-type Cultivars of Tall Fescue

Biotechnology approaches can supplement conventional breeding efforts for turfgrass improvement. The objective of this study was to develop reliable transformation and selection schemes for elite turf-type tall fescue cultivars. Transgenic tall fescue (Festuca arundinacea Schreb.) plants were obtained by microprojectile bombardment of embryogenic suspension cells of two elite turf-type cultivars, ‘Coronado’ and ‘Virtue’. Two selection systems were successfully used in the transformation. A bialaphos-based selection used plasmid pAHC25 that contains phosphinothricin acetyltransferase (bar) and β-glucuronidase (GUS) genes both driven by the maize ubi1 promoter. A two-step solid medium selection with increasing bialaphos concentration was used to obtain resistant callus. Alternatively, a hygromycin B (hyg B)-based selection strategy was employed using plasmid pAcH1 containing a hygromycin phosphotransferase (hph) gene driven by the rice Act 1 gene promoter. A three-step liquid medium or a two-step solid medium selection was used to obtain resistant callus. Additional selection in the rooting medium eliminated escapes. Expression of the bar and GUS genes was demonstrated by resistance to the herbicide ‘Finale’ and by GUS activity assays, respectively. The transgenic nature of the resistant plants was confirmed by Southern hybridization analysis. Department of Crop Science, North Carolina State Univ., Raleigh, NC 27695-7620. *Corresponding author: [email protected]