Figure 2.

1-Aminocyclopropane-1-carboxylic acid (ACC) reduces root initiation in Col, but not in ethylene-insensitive mutants. Seedlings were grown on control media for 5 days and were then transferred to 1 μm ACC or the indicated concentration, or 10 μm silver nitrate, for five additional days.

(a) Lateral root phenotypes are shown with a scale bar of 5 mm. (b and c) The effects of a range of ACC concentrations on the number of lateral roots or the root length were determined, with the average and SE of 30 seedlings reported here

(d) The average number of lateral roots and SE of 30 Col seedlings for each treatment are shown with significant differences (P < 0.01) compared with untreated seedlings, indicated by the letter ‘a’, or with and without silver treatment, indicated by ‘b’, and silver treatment with or without ACC, indicated by ‘c’

(e) The number of lateral root early primordia, emerged lateral roots, and the combined totals were determined by CYCB1;1:GUS expression. The average and SE of 20 seedlings are reported, and significant differences between treatments and within stages were determined by a Student’s t-test, P< 0.001.