Figure 2.
Decreasing Competence of Restorative Divisions Correlates with PLT Activity
(A) Tile scan of a root 24 h after ablation of cortex and epidermis. While ablation of cortex cells (red asterisk) induced periclinal cell divisions in endodermis (red arrows), ablation of epidermis (green asterisk) did not induce periclinal division in cortex, which lost the competence to divide. In contrast, ablation of epidermis closer to the quiescent center induced the periclinal cortex cell divisions. Marked ablated cells moved from meristem into elongation zone during growth.
(B) Number of periclinal divisions decreases with distance from QC as measured in various cell types after 16 h depending on distance from the QC at the time of ablation (μm). Total number of ablations: n = 15–50 for every 10 μm (70–250 μm).
(C) Number of periclinal divisions in cortex and endodermis cells depending on the distance from the QC at the time of ablation is increased after PLT2 induction as measured in WT and 35S::PLT2-GR (treated with 5 μM DEX 1 h prior ablation) 12 h after ablation. Roots with ectopic oblique divisions were excluded from the quantifications. Number of ablations per data point: n = 3–26.
(D) Overexpression of PLT2 starting 1 h before ablation triggered periclinal and oblique divisions in inner adjacent cells. Cortex cells are already partly elongated. Ablation was performed at 282 μm from the QC.
(E) Number of periclinal divisions after ablation in plt1, plt2 single, and plt1plt2 double mutants in different cell layers at random distance from the QC after 12 h. Data are represented as weighted mean (bar) and individual experiments (dots, area indicates sample size). Asterisks correspond to p values from conditional logistic regression (CLR); plt1 (cortex): 0.000538, plt2 (endodermis): 0.0231, plt1plt2 (epidermis): 9.99E−07.
(F) Periclinal division was not induced in epidermis in the plt1plt2 double mutant 12 h after ablation.
Red asterisks: sites of ablation. Roots were stained with PI.