Effects of different concentrations of IAA and PCIB on primary root elongation. Five-day-old seedlings grown vertically were transferred to fresh medium containing IAA and/or PCIB at different concentrations and cultured vertically for another 5 d. A and B, Dose response of PCIB in the presence (white circle) or absence (black circle) of 0.1 μm IAA (n = 40; A), and dose response of IAA in the presence (white diamond) or absence (black diamond) of 5 μm PCIB (n = 20; B). The average of elongated length with se during 5 d of incubation was presented. Absence of bars indicates error less than size of symbol. The same data were plotted as a percentage of root elongation and shown in the upper right corner. C, Relative root elongation in the auxin-related mutants (n > 30). Mean values (cm) ± se in the absence of PCIB for 100% root growth were 3.54 ± 0.07 (Col-0), 4.82 ± 0.12 (axr1-3), 3.44 ± 0.08 (axr2-1), 3.38 ± 0.01 (tir1-1), 3.89 ± 0.11 (aux1-7), 4.11 ± 0.11 (aux1-22), 3.34 ± 0.11 (eir1-1), and 3.73 ± 0.12 (ein2-1).