Luciferase and GUS expression over time. Protoplasts were prepared from 2-week-old kitaake plants and transformed as described (Methods). Luciferase (Top) or GUS (Bottom) activity was measured at 0, 4, 8, 14, 20, and 24 h post transformation. At each time point, cells were lysed by vortexing for one minute in lysis buffer (Methods) and frozen at -20°C until the experiment was complete. After the final time point, reporter gene activity was measured for all samples as described in Methods. Error bars represent 3 replicates at every time point.