Fourteen-day-old DWF4::GUS transgenic seedlings were cultured for 1 day in liquid MS medium containing IAA and one of either three anti-auxins (PEO-IAA, BH-IAA or PCIB) or two PAT inhibitors (TIBA or NPA) at the indicated doses. GUS activity was analyzed biochemically (A) and histochemically (B). In the graphs, the GUS activity (the mean ± SD) of a representative result among three independent measurements is shown as a value relative to that of the untreated control. The photographs represent the shoots (a–f) and roots (g–l) of transgenic Arabidopsis. The magnification is same in all the photographs, and the bar indicates 1.0 mm (a). PCIB, 2-(p-chlorophenoxy)-2-methylpropionic acid; PEO-IAA, α-(phenylethyl-2-one)-IAA; BH-IAA, α-tert-butoxycarbonylaminohexyl-IAA; TIBA, 2,3,5-triiodobenzoic acid; NPA, N-1-naphthylphthalamic acid.