The ctu2-2 mutant is affected in root development. A) The ctu2-2 mutant shows a reduction in lateral root formation compared to wild-type Columbia (WT) and the complemented ctu2-2 mutants (indicated by an asterisk; p = 0.01; n ≥ 15), determined after 8 days of growth in a vertical orientation. The complementation lines are the same as shown in Figure 2. The tRNA thiolation-defective rol5 mutant also shows a reduction, which is significantly stronger than in ctu2-2 (indicated by two asterisks; p = 0.05; n ≥ 15). Error bars represent the standard error of the mean. B) In contrast to wild-type Columbia, 7 days-old lrx1 mutant seedlings develop aberrant root hairs. This phenotype is suppressed by ctu2-2, resulting in wild type-like root hair formation in the lrx1 ctu2-2 double mutant.