Extended Data Fig. 6: Reduction in hypoxia signalling level mediates periderm regeneration.

a, Cross sections of 14-day-old intact proPCO2:erVenus roots. b, Cross sections of 21-day-old proPCO2:erVenus roots right after or two days after the injury. Quantification of proPCO2:erVenus signal intensities in the vascular region at 0 and 2 dai. Two-tailed Welch’s t-test was used (**; P < 0.01). c, Cross sections of intact proPCO1:erVenus and proPCO2:erVenus roots and their roots 16 or 24 h after the injury. Quantification of proPCO1:erVenus and proPCO2:erVenus signal intensities in the vascular region of intact roots or at 16 and 24 h after the injury. Kruskal-Wallis test (P < 0.05) followed by two-sided Mann-Whitney U-test with the Bonferroni adjustment was used to test significant difference (different characters indicate statistically significant differences between two groups; P < 0.05). d, Cross section of wild-type root used for oxygen measurement. Inferred depth where the oxygen microsensor was placed before (yellow) and after (orange) removal of the periderm. e, Schematic drawing of the microsensor insertion site. The histological analysis suggests that the microsensor was inserted in the region around the distal phloem parenchyma cells or from the phloem-side cambium to the vascular cambium before or after the removal of the periderm, respectively. Considering that the microsensor appeared to be inserted into metabolically more active region after peeling off the periderm compared to intact root, higher oxygen level after injury indicate that the periderm prevents oxygen intrusion. f, Cross sections of 21-day-old prt6-5 roots at 4 dai grown on MS (Mock) or 10 µM ACC-supplemented MS (ACC) plates for four days after the injury. prt6 mutant phenotype was different compared to ate1-2;ate2-1 likely due to its redundant partner, BIG⁴⁷. g, The proportion of cross sections showing callus-like structure at the wound site in mock and ACC-treated 21-day-old wild-type and prt6-5 roots at 4 dai. Two-sided Fisher’s exact test was used to test significant difference between Mock- or ACC-treated prt6-5 (**; P < 0.01). h, The signals of 35S:EIN3-GFP in root tips. Three-days-old 35S:EIN3-GFP seedlings were grown on MS (Mock) or 10 µM ACC-supplemented MS (ACC) plates in ambient air or on MS (Hypoxia) or 10 µM ACC-supplemented MS (ACC + Hypoxia) plates under 5% oxygen concentration for one day. n indicates the number of examined cross sections. Fractions on the panel indicates the proportion of cross sections showing similar callus-like structure formation or root tips showing the similar expression as in the images. Venus signal intensities in a,b,f, GFP signal intensities in h and intensity of suberin staining with Fluorol yellow in f are shown according to the colour map on the right. Red in d, Basic Fuchsin. White, SR2200 (cell wall). Scale bars: 50 µm.

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