Fig. 4: Relevance of the G1 duration gradient.
From: Stem cell regulators drive a G1 duration gradient during plant root development
a, G1 duration is regulated at different stages of LR development. For quantification, the LRPs of seven-day-old PlaCCI seedlings were classified by size and divided into two halves: the distal half (solid blue circles) towards the apex of the LRPs and the proximal half (empty circles) towards the base of the LRPs. The data points correspond to the G1 duration of individual cells quantified from different recorded videos (up to 21 h long using confocal microscopy), and the median is represented. The number of cells recorded is indicated for each LRP size class below each data distribution inside the graph, all collected from nine LRPs of three roots. Statistical significance was determined using non-parametric Mann–Whitney rank sum tests (two sided): NS, not significant (P > 0.05); ****P < 0.0001. Representative images of the LRPs analysed at different developmental stages are shown below the graph. Scale bar, 40 µm. b, KRP5 protein level is also regulated at different stages of LR development. LRPs were classified by size, as in a. Quantification of KRP5–GFP signal was carried out in the distal and proximal halves of the LRPs, as described in a. The data points correspond to the KRP5–GFP signal intensity of individual cells, and the median is represented. The number of cells recorded are indicated for each LRP size class below each data distribution inside the graph. The number of LRPs scored for each size class was n = 6 for 0–50, n = 7 for 51–70, n = 6 for 71–90, n = 4 for 91–110 and n = 7 for >111 from five roots. Statistical significance was determined using Mann–Whitney rank sum tests (two sided): NS, P > 0.05; ****P < 0.0001. Representative images of LRPs analysed at different developmental stages are shown below the graph. Bright-field images of the same LRPs shown are included to facilitate visualization of the LRPs (highlighted with dashed yellow lines). Scale bar, 40 µm. c, Plants with a G1 duration gradient show a more robust response to DNA-damaging treatments. The left plot on each side shows the root growth kinetics of plants transferred at four days post sowing to an MSS medium (as described in Methods) in the absence (control) or presence of zeocin (2.5 µg ml−1) of the wild type and the indicated mutants. The right plot on each side shows the quantification of root size measured at the end of the experiment (seven days after treatment). The colour code is as indicated in the left plots. The data points correspond to individual roots. The root sample sizes were as follows: in the control treatment, n = 9 for the wild type, n = 10 for krp5-1, n = 8 for krp1,2,3,4,5,7 and n = 5 for rRBr/rbr1; in the zeocin treatment, n = 11 for the wild type, n = 15 for krp5-1, n = 13 for krp1,2,3,4,5,7 and n = 6 for rRBr/rbr1. Statistical significance was determined using one-way analysis of variance followed by two-sided Tukey’s multiple comparison tests (NS, P > 0.05; ****P < 0.0001).
