Figure 3. Temporal expression patterns of PStSN1::GUS in Arabidopsis. Plants were collected at 1, 2, 3, 4, 5 and 6 weeks after emerging from seeds for histochemical localization of GUS activity in sequential developmental stages. Staining representative plants of transgenic harboring PStSN1::GUS construct is presented and one 35S::GUS control line (called Control 35S). After staining some leaves were detached to analyze in detail the gradual decrease in promoter activity as plants aged.