Figure 3

PAT Interruption in the primary stem releases buds from dormancy.

(a) Scheme of plant wounded above the upper bud. Red arrows represent auxin (IAA) flow; red arrow crossed with black X represents disabled auxin flow. Green arrow represents bud outgrowth. Weakening stem auxin flow facilitated auxin export from the upper bud and its outgrowth. The lower bud remained arrested in dormancy by auxin loaded from the upper bud. (b) Scheme of intact plant subapically treated with TIBA-ring. Arrows as depicted in a). Auxin efflux inhibitor blocks auxin flow from the apex and the upper bud becomes a new auxin source, which continues to prevent auxin transport from the lower bud. (c) Wounded plant. Black arrow points to the lateral shoot formed from the upper axillary bud, above which the stem was incised. (d) Length of axillary buds and forming shoots, where: (li) lower bud of intact plants, (ui) same plants, upper bud, (liTs) lower bud of intact plants subapically treated with TIBA-ring, (uiTs) same treatment, upper bud. Statistically significant differences (identified by Student’s t-test) α = 0.05* and α = 0.01**. Error bars represent standard deviations (n = 60). (e) Relative expression of PsDRM1 gene in the lower and upper axillary bud of intact plants subapically treated with TIBA-ring. Statistically significant differences (identified by Student’s t-test) α = 0.05* and α = 0.01**. Error bars represent standard deviations (n = 4). (f) [³H]-IAA transport from the apex in stem subapically treated with TIBA-ring was measured in two stem sections at a distance of 0–4 and 4–8 mm under the TIBA application site. Statistically significant differences (identified by Student’s t-test) α = 0.05* and α = 0.01**. Error bars represent standard deviations (n = 10). (g) PIN1 auxin efflux carrier immunoanalysis (red signal) in stem cells at TIBA-ring position exhibited no visible changes in organization. Stage 24 h after treatment. Scale bar, 100 μm.