The hda6 mutant displays ectopic development of hair cells at the N position in the root epidermis. A, Schematic representation of hda6 point mutations. There are two sil1 mutant lines, CS1894 and CS1895, both with a point mutation 46 bp after the start codon that results in the replacement of Gly-16 by Arg. The axe1-4 mutant has a base substitution at the second intron-exon junction (1,492 bp downstream of the start codon). The short black lines indicate regions selected for quantitative reverse transcription (qRT)-PCR. B, Cross sections of root tips of Col, axe1-4, and overexpression line (top row, left to right), and Ler, sil1 (CS1894), and sil1 (CS1895; bottom row, left to right). Arrows indicate ectopically developing hair cells. Bars = 20 μm. C, Cross sections of root tips of hda6 complementation lines harboring a genomic HDA6 DNA fragment. Bars = 20 μm.