Figure 3.

Dark-grown ctr1 seedlings respond to ethylene treatment. A, Dark-grown ctr1-3 seedlings grown in air or 10 μL L⁻¹ ethylene for 3.5 d. B, Hypocotyl length of the wild type (Col-0) and three different ctr1 mutant alleles grown in the dark for 3.5 d either in the presence or absence of 10 μL L⁻¹ ethylene gas. The ctr1-1 missense mutation results in an amino acid substitution of a highly conserved residue within the kinase domain. ctr1-3 carries a stop codon in the N-terminal regulatory domain. The ctr1-15 mutation has not yet been identified. Mean ± se values were determined from 25 to 30 seedlings. C, Hypocotyl diameter of the wild type (Col-0) and the three ctr1 mutant alleles treated as in B.