siRNA silencing over time. Protoplasts were prepared from 2-week-old kitaake plants and transformed as described (Methods). Top line: 5 μg of pLUC transformed into protoplasts as described. Bottom line: 5 μg pLUC and 3 μg of siRNA to luciferase co-transformed into protoplasts. Luciferase activity was measured after 3,6, 13 and 19 h. Each time point represents 3 replicates and standard errors are displayed.