Fig 7. YUC8/REIN7-mediated auxin biosynthesis is required for ethylene-inhibited root growth in etiolated seedlings.

(A) DR5-GUS expression in root. Seedlings of 3-d-old etiolated transgenic lines containing DR5-GUS in the wild type or the rein7-1 background were treated with or without 10 ppm ethylene for 8 h before GUS activity was assayed. Bar = 10mm. (B) Root tip and elongation zone in (A). ‘RT’ represents root tip, ‘EZ’ represents elongation zone. Bar = 100 μm. (C) qPCR analysis of auxin-response gene expression in response to ethylene. Dark-grown 3-d-old wild-type seedlings were treated with 10 ppm ethylene for 3 h. The RNAs from roots were isolated for qPCR. (D) IAA levels in 3-d-old wild-type and rein7 etiolated seedlings in the absence or presence of 10 ppm ethylene. (E) Rescue of the reduced ethylene sensitivity of rein7-1 root by IAA. The wild-type and rein7-1 seedlings were grown in the dark for 3 d in the absence or presence of 10 ppm ethylene, with or without supplementation of 10 nM IAA. Bar = 10 mm. (F) Quantification of root inhibition in (D). Each column is the average of 20–30 seedlings. The data are shown as the mean ± SD of three biological replicates. * and ** indicate significant differences between the compared two samples at P < 0.05 and P < 0.01, respectively.