Fluorometric quantification of GUS activity. GUS enzyme activity among different transgenic groups in leaves, stems and roots. The GUS activity is expressed in μg 4-methylumblliferone min-1 mg-1 protein, and a graph drawn of the average rate of GUS activity per collection of transgenics per construct. The quantification of GUS activity for each promoter construct was replicated three times. Statistical analysis was performed using least significant difference and homogeneity of variance test by SPSS 16.0, and one way ANOVA test was used for the statically analysis. Means with different lower-case or upper-case letters were statistically different at P < 0.05 among segments and between tissues, respectively. Error bars on the graph represent SE with three replicates.