Figure 6.

Effects of PISA on IAA-induced lateral root formation and shootward IAA transport. A, Effects of PISA on the lateral root formation. Arabidopsis seedlings were cultured for 6 d with PISA. The number of lateral roots were counted and the density of lateral roots are shown as box-and-whisker plots (n = 14–16). B and C, Effects of PISA on IAA-induced lateral root formation. Five-d–old seedlings were cultured for additional 3 d with PISA in the presence of IAA. The density of lateral roots are shown as box-and-whisker plots (B, n = 14–16) and representative images are shown (C). Bar = 5 mm. D, Effects of PISA on IAA-induced DR5::GUS expression. Five-d–old DR5::GUS seedlings were incubated for 12 h in liquid GM medium with or without PISA or auxin transport inhibitors. IAA was added to the GM medium and the seedlings were further incubated for additional 6 h. The IAA-induced GUS activity was visualized by X-Gluc. Bar = 1 mm. E, Effects of PISA on shootward IAA transport. An agar block containing IAA was applied to DR5::GUS root tips (yellow ring) and the seedlings were incubated on vertical plates containing 40-μm PISA for 10 h. Arrows show the IAA-induced GUS activity. Bar = 1 mm. Statistical significance assessed by Welch’s two-sample t test. Asterisks in (A) and (B) indicate significant differences (*P < 0.01). The values in parentheses represent the concentration of chemicals (micromolar).