ETO1 suppresses auxin-induced ethylene production in tomato. A. Six-day-old etiolated seedlings of T2 homozygous lines, 14-1-H2 (ETO1 +/+) and 14-1-H4 (ETO1 -/-) were treated with 2,4-D (in 1% ethanol) at the final concentration of 100 μM for 1 d. Ethylene concentration in the headspace was measured by a gas chromatograph. Means ± SE (n = 8) are indicated. B, Induction of LE-ACS3 by 2,4-D. Total RNA (10 μg) from etiolated seedlings (ETO1 +/+ or -/-) with or without 2,4-D treatment was probed with LE-ACS3. Four individuals were used for each treatment. Arrowhead indicates the functional unspliced transcript size .