Fig. 3: The trade-off between regeneration of callus and root is determined by the availability of water.

a, Root or callus regeneration in Arabidopsis leaf petioles with wound sites either touching or non-touching on media with different agar concentrations, or on parafilm with or without water (10 days after wounding). The dashed line marks the wound site. A, agar; P, parafilm; W, water. b, Root or callus regeneration in Arabidopsis leaf petioles placed on parafilm–agar sandwich set-ups: parafilm–petiole–agar or parafilm–petiole–parafilm–agar (10 days after wounding). Insets show the leaf (dashed red line) in the set-up. c, The regeneration frequency in Arabidopsis leaf petioles under varying water availability (n = 39, 40, 40, 40, 39, 39, 40, 40 and 28 (left to right) independent explants; mean). d, The regeneration frequency in Arabidopsis leaf petioles under sandwich set-ups (n = 20 independent explants per condition; mean). Underlining indicates the order of layers. e, The regeneration frequency in tomato cotyledon petioles under different agar conditions (n = 22 independent explants per condition; mean). f, Regeneration in tomato cotyledon petioles on 0.75% or 3% agar, 10 days after wounding. The dashed line marks the wound site. g,h, Images (g) and regeneration frequency (h) in tomato stems during air layering with wet or dry soil (n = 18 independent explants per condition; mean). Wound sites are marked by a rectangle (0 days) and green arrowheads (8 days wet soil) and calli are marked by a white arrowhead. i, The average number of regenerated roots per tomato cotyledon explant on auxin-containing (0.5 mg l⁻¹ indole-3-acetic acid, IAA) RIM with varying agar concentrations (n = 19, 18, 19, 18, 19 and 17 (left to right) independent explants; letters indicate significant differences (P ≤ 0.05), Kruskal–Wallis with pairwise Wilcoxon; box plot shows median (central line), mean (cross), first and third quartiles (top and bottom edges), and minimum and maximum values excluding outliers (whiskers)). j, The transcriptional dynamics of genes associated with callus and root regeneration in Arabidopsis. Scale bars, 500 µm (a and b), 1 mm (f) and 5 mm (g).