For the rapid establishment of optimal conditions for a genetic transformation system for tall fescue, several factors influencing transient gene expression were studied in protoplasts, after the reporter β-glucuronidase (GUS) gene was introduced by electroporation. In a time-course study of transient gene expression, GUS activity peaked at 24 h after electroporation. Among the different field strength conditions tested, maximum GUS activity was observed at 750 V/cm. Increases in the amount of plasmid DNA to 80 μg/ml led to increased GUS activity. GUS activities increased in linear fashion with increasing protoplast densities up to 2 x 10⁶/ml. Age of suspension cells from which protoplasts were derived influenced transient expression with maximum GUS activity obtained in 3 and 5 day old suspensions. These results show that transient expression studies can be used to optimize electroporation parameters rapidly. Results of such rapid assays can be used as a basis for further studies on stable transformation of this important turf-grass species. / Master of Science