Figure 3.

Auxin signaling and transport inhibitors repress PISA-induced hypocotyl phenotypes and PISA promotes basipetal auxin transport in the hypocotyl. A, The hypocotyl length of Arabidopsis wild-type and axr1-3 mutant seedlings cultured for 7 d with chemicals. Relative hypocotyl length is shown as the percentage of that in mock-treated plants (100%). The actual length (millimeter) of mock-treated hypocotyls are indicated (n = 40–48). B, Seedlings cultured for 7 d with PISA and auxin transport inhibitor, TIBA. C, Hypocotyl length in seedlings cultured with or without TIBA and PISA. Relative hypocotyl length is shown as the percentage of that in mock-treated plants (100%). The actual length (millimeter) of mock-treated hypocotyls is indicated as box-and-whisker plots (n = 40–45). Statistical significance assessed by Welch’s two-sample t test. Asterisks indicate significant differences (**P < 0.05, *P < 0.01). D, Seedlings of wild type, arf7 arf19, and slr1/iaa14 mutants cultured for 7 d with or without PISA. The values in parentheses represents the concentration of chemicals (micromolar). Bar = 5 mm. E, Rootward transport of radiolabeled ³H-IAA in decapitated hypocotyls. NPA, an auxin transport inhibitor, was used as the negative control. (*P < 0.01, n = 9).