Fig. 1: Cell-type-specific expression of YUC1 and TAA1 impedes root growth and reveals rapid auxin movement.

a TAAs- and YUCs-Trp-dependent IAA biosynthesis pathway. b Schematic diagram of the cell-type-specific promoter XVE vector. Upon estradiol treatment, the XVE fusion protein transcriptionally activates expression of YUC1 and TAA1 in specific cell types. The sequence encoding the 2 A self-cleaving peptide sequence is located between YUC1 and TAA1. c Root elongation of seedlings expressing cell-type-specific YUC1-TAA1 (YUC1-2A-TAA1) vectors. Seeds were sown on MS, and seedlings were transferred on day 4 to plates containing 5 μM estradiol. Root length was scored after 7 days and normalized to root length of control plants (no estradiol treatment) at the same age (Supplementary Fig. 1). Shown are means (±SE), n ≥ 15 plants (Ctr, pWER, pSCR, and pWOX5 = 15, pSHR = 18, pAPL = 19), ****P < 0.0001 by two-tailed t test. d Expression patterns of GFP produced from cell-type-specific promoters in 5 day-old seedlings at 24 h after estradiol induction (5 μM). pWOX5 is pWOX5:mCHERRY. GFP or mCHERRY are not part of the YUC1-2A-TAA1 construct. Scale bar = 100 μm. Propidium iodide staining is shown in red. e Representative images of seedlings that express cell-type-specific YUC1-TAA1 at 1 week (1 w) after estradiol treatment (5 μM). Only the upper part of the root is shown. The roots are not shown as a whole. Scale bar = 2 mm. f–g DR5:VENUS response following cell-type-specific auxin production. Plants were treated on day 5 with estradiol (5 μM) for f 6 h and g 24 h. White arrows indicate DR5:VENUS activation in epidermal-elongating cells of pWOX5:XVE:YUC1-TAA1. Green: DR5:VENUS signal; red: propidium iodide dye marking cell walls. Scale bar = 100 μm. The experiments were independently repeated three times.