Hypocotyl Measurements

For hypocotyl elongation assays, surface-sterilized seeds were sown on 0.5× MS media containing 1.0% (w/v) Suc, 0.7% (w/v) agar and 100 nM GR24^4DO, GR24^ent-5DS, or GR24^4DO plus GR24^ent-5DS (100 nM of each chemical). The seeds were stratified in the dark at 4°C for 72 h, exposed to white light from a fluorescence tube (∼60 to 80 μE m⁻² s⁻¹) for 3 h at 21°C, transferred to dark for 21 h, and then exposed to continuous red light (∼20 to 30 μE m⁻² s⁻¹) for 4 d at 21°C as previously described (Stanga et al., 2013). The lengths of the hypocotyls were measured using ImageJ (http://rsbweb.nih.gov/ij/).