Fig 4. The ctl1 mutant shows auxin-related phenotypic changes.

(A) Representative images of the apical hooks of the wild type (WT), ctl1, and the ctl1 complementation line (ctl1C) at 36, 60, and 84 hours after germination in the dark. (B) Kinetic analysis of apical hook angles of etiolated seedlings of WT, ctl1, and ctl1C during apical hook development. Data are mean ± SD of 4 replicate experiments. (C) Representative images of phototropic growth of WT, ctl1, and ctl1C seedlings. After being vertically grown on half-strength Murashige and Skoog (MS) medium in the dark for 2 days, the seedlings were exposed to unilateral light for 2 days before the photographs were taken. (D) Quantitation of the phenotypes shown in panel C. The bending angles of the hypocotyls towards the horizontal direction were measured using the ImageJ software. The percentages of seedlings in each of 3 categories (<20°, 20–40°, and >40°) were calculated. WT, n = 116; ctl1, n = 119; and ctl1C, n = 119. (E) Growth phenotype of 10-day-old WT and ctl1 mutant plants grown on half-strength MS medium containing 0, 0.1, or 0.3 μM 1-naphthylacetic acid (NAA). Bars = 1 cm. (F) The ctl1 mutant shows reduced NAA sensitivity. Relative root length (%) indicates shortening of the primary roots as a result of NAA in the medium. Data are mean ± SD. Three independent experiments were performed. n = 6 for each experiment. The raw data for panels B, D, and F can be found in S1 Data.