Fig. 2.

IAA export from excised shoot tips as a function of the shoot tip weight for (A) 10-day-old, (B) 12-day-old, and (C) 16-day-old 2-B and 1-B pea seedlings. A schematic of the experimental set-up is shown on the left. (D, left side) Age dependence of IAA export activity from 2-B and 1-B shoot tips with a standard weight of 45 mg. (D, right side) IAA transport from intact 2-B and 0-B de-rooted seedlings collected for 2 h into distilled water or 0.5 mM EDTA, pH 7.05 (150 µl per plant). Plants were prepared as in Fig. 1 and diffusible IAA from each excised shoot tip was collected into 120–150 µl of distilled water for 2 h. Diffusates from six shoot tips with similar weight (≤5 mg) were combined for ELISA. In (A–C), the data were analyzed using linear regression (SigmaPlot 11 for Windows 7); in (D, left side), values were interpolated by linear regression of existing data points in (A–C) ±SE. In (D, right side), data are expressed as the mean ±SE of three samples pooled from five shoot diffusates. In (D), asterisks indicate statistically significant differences compared with 2-B plants: *P<0.05; **P<0.01, ***P<0.001.