Assay of PPO protein level, enzymatic activity and browning potential in transgenic potato tuber tissues. (A) Relative PPO protein level (RPR). (B) Relative PPO activity (RPPO). (C) Relative browning potential (RBR). Each box plot presents the data from three biological and three technical replicates of the transgenic and non-transgenic (WT) potato tubers. All data are presented relative to the level of the WT. A line across the box indicates the median. The box indicates the 25th and 75th percentiles. Whiskers represent the maximum and minimum values. Different lower case letters indicate values are significantly different at P < 0.05 level; different capital letters indicate values are highly significantly different at P < 0.01 level based on Duncan’s Multiple Range Test.