Figure 4.

Induction of etr1-1 expression from p1002 and p1003 in tomato determines the level of sensitivity to exogenous ethylene. Seeds from line 2-18 (containing p1002), line 3-16 (containing p1003), or the wild type (WT) were germinated in the dark in air for 2 d in vermiculite containing the concentration of DBAH indicated and then grown in either air or 10 μL L⁻¹ ethylene as indicated for an additional 10 d. Two representative seedlings are shown for each line. Quantitative measurements for hypocotyl and root lengths with sd are shown in the histograms to the right of each panel. Ten to 20 seedlings were used for each measurement. The P values represent the statistical significance between each starred bar relative to the 0-μm DBAH control in the presence of 10 μL L⁻¹ ethylene: * P < 0.001, ** P < 0.005, *** P < 0.05.