Figure 1.

Phenotypic characterization of arg1 seedlings (28). (A) Average hypocotyl tip angles from the horizontal of dark-grown 4-day-old wild-type (WS) and arg1–1 and arg1–2 mutant seedlings, 0 and 72 hours after rotating the plates by 90°. The two series of measurements were done on separate plates and involved 96 and 112 plants, respectively. SDs are shown by thin lines on the top of each bar. A legend to A–D is provided in F. (B) The kinetics of root bending on gravistimulation. Seedlings (4 days old) were reoriented 90° at time zero. Root-tip angles from the horizontal were measured over time, and average angles along with SD (vertical bars) were calculated (n = 57–78). (C) The kinetics of hypocotyl bending on exposure to a horizontal light source. Seedlings (4 days old) were exposed to a horizontal light source at time zero. Hypocotyl tip angles from the vertical were measured over time, and average angles along with SDs (vertical bars) were calculated (n = 23 and 30). (D) The effect of 2,4-D on average root growth of wild-type WS and of mutant arg1–1 and rgr1 (auxin-resistant control; ref. 17) seedlings. Seedlings (4 days old) were placed on media containing the indicated concentrations of 2,4-D (x axis) at time zero. Average root growth rates (mm per 12 hours) along with SDs (vertical bars) were calculated and plotted (n = 12–19). (E) arg1–1 and arg1–2 seedlings accumulate starch in their statocytes like wild type. Wild-type WS (Center) and arg1–1 (Left) and arg1–2 (Right) mutant seedlings (7 days old) were stained with IKI and analyzed under a light microscope equipped with Nomarski optics (×20).