IAAld rescues the rhd6 mutant phenotype. A, Wild-type Col-0 Arabidopsis root with normal root hair formation. B and C, Root hair formation in response to IAA (B) or IAAld (C) treatment. D, A typical rhd6 Arabidopsis mutant root showing a reduction in root hair formation. E and F, Formation of root hairs in rhd6 roots in response to IAA (E) or IAAld (F) treatment. The experiment was repeated three times with similar results. DMSO, Dimethyl sulfoxide. [See online article for color version of this figure.]