Fig. 5: Cytokinin signalling through root CEPDs inhibits primary root growth.

a Representative images and (b) relative primary root growth for No-0, cepr1-1, and the cepd1,2 double mutant seedlings 3 days after transfer to medium with or without tZ (10 nM) (n = 11–24 plants). Horizontal bars in (a) indicate the length of the primary root on the day of transfer (i.e. 6 days growth). Root growth post transfer expressed as a percentage of seedlings grown on solvent control (DMSO) for each respective genotype. c tZ sensitivity of reciprocal hypocotyl grafts between No-0 and cepd1,2. Primary root growth 3 days post transfer to tZ (5 nM) expressed as a percentage of seedlings transferred to DMSO (control) for each respective graft combination (n = 4–8 plants). d Relative primary root growth for No-0 and cepd1,2 seedlings 3 days post transfer to segmented plates for tZ treatment of roots and/or shoots. See lower panel for diagrammatic representation of the segmented agar plate set-up. Plants were grown for 6 days before transfer to segmented plates with tZ (10 nM) or solvent control (DMSO) infused in each plate segment. Plants were positioned such that roots only were in contact with the bottom segment, and shoots only were in contact with the top segment. Root growth post transfer expressed as a percentage of the DMSO control for each respective genotype (n = 13–18 plants). Letters in (b–d) show significant differences (ANOVA followed by Tukey HSD test, p < 0.05). Scale bar = 1 cm. Box plot centre line, median; box limits, upper and lower quartiles; whiskers, 1.5x interquartile range. See Supplementary Fig 7 for associated absolute root growth measurements and representative images. Exact p values and sample sizes for each treatment group are provided in the Source Data file.