Fig. 1: CPK1 is required for RH growth in Arabidopsis.

4-5 day-old seedlings growing in Petri dishes were used for RH phenotype analysis. A set of optical section images of the RHZ of the seedlings with a 22.5 µm sectioning step and a sectioning speed of 5 steps/sec were captured under a stereo microscope at room temperature (25 ± 1 °C), and the set of images were automatically and immediately merged into a 2-D picture for each Petri dish. The 2-D pictures were used for RH phenotype analysis. For the time-lapse analysis of RH elongation rate and growth time, the optical sectioning was performed every min for 300 min for each dish, and the merged 2-D photos were used to analyze the RH elongation rate and time. a, b Typical 2-D photos derived from optical sectioning images of the RHZ of seedlings (a) and individual RHs showing the typical RH shapes (b). c–g Statistical analyses of RH length (c), RH branching rates (d), RH density (e), RH elongation rate (f), and RH elongation time (g). Scale bars, 0.2 mm in (a), and 10 μm in (b). c–e The numbers of biologically independent roots with approximate 50 RHs per root examined in this study are 11, 14, 10, 15, 11, 11, 14, 12, 17, and 12 for RH length (c), 12, 14, 11, 10, 10, 11, 10, 13, 15, and 12 for RH branching (d), and 10, 10, 11, 13, 10, 12, 13, 12, 13, and 9 for RH density (e), for the 10 Arabidopsis lines as shown from left to right in each panel. f, g n = 20 roots for both WT and cpk1-1. Samples with different letters are significantly different with P < 0.05 (one-way ANOVA) in (c–e), and P < 0.01 (two-tailed Student’s t-test) in (f, g). Data are presented as means ± SEM. Source data are provided as a Source Data file.