Figure 5.

Stage-Specific Inhibitory Effects of ABI4 on LR Development.

(A) and (B) LRs were counted in roots of 12-d-old seedlings in each of four developmental stages (De Smet et al., 2003): Stage A, initials with up to two layers of cells; stage B, three or more layers of cells just prior to emergence; stage C, immediately after emergence but <0.5 mm long; stage D, LRs longer than 0.5 mm.

(A) Effects of ABI4 overexpression on LR number: wild-type plants (black bars), 4C-S5 plants transformed with empty vector (white bars), or three lines of ABI4 overexpressors (gray bars) were germinated on 0.5× MS plates with (transgenic plants) or without (wild type) 2 μM Dex.

(B) Effects on LR number in abi4 mutants: the wild type, abi4-1, abi4-102, and abi4-103 mutants were germinated on 0.5× MS plates.

(C) Initial growth rates of LRs of abi4 mutants. The lengths of the first two visible LRs of 1-week-old vertically grown seedlings were measured. The added lengths at 24 and 48 h are presented. The data represent the mean ± se of n = 3 independent experiments each containing 20 plants per treatment. Bars with different letters represent statistically different values by Tukey’s HSD post-hoc test (P ≤ 0.05).