Supplemental Information A Molecular Framework of Light-Controlled Phytohormone Action in Arabidopsis

Plant Materials and Growth Conditions The wild-type (WT) Arabidopsis seedlings used in this study is Columbia-0 ecotype. All ethylene mutants [1, 2], PIF3OX [3], iE/qm [4] , pif1 pif3 pif4 pif5 and pif3-3 [5] were lab stocked. pif1 (SALK_131872C) [6], pif3 (SALK_081927C) [2], pif3-1 (SALK_030753) [7], pif4 (SALK_140393C), pif5 (SALK_087012C) [8], erf1 (CS481507), erf6 (SALK_030723), erf11 (SALK_116053) mutants were acquired from ABRC and identified by PCR genotyping. Double, triple and quadruple mutants were generated by crossing and homozygous lines were genotyping confirmed. Surface-sterilized seeds were sown on MS medium with half dosage of MS salts and sucrose (2.2g/L MS salt, 0.5% sucrose, PH 5.7, and 8g/L agar) and imbibed for 3d at 4°C in dark. For ethylene treatment, plants were grown on MS medium supplemented with 10 μM ACC. Germination was induced by 6h of irradiation with white light at 22°C before transferring to different growth conditions. Light-grown seedlings were grown under fluorescence white light (about 130μmol m -2 s -1 ) with a 12h light/12h dark photoperiod unless indicated. Dark-grown seedlings were exposed to 5-min far-red light (about 10μmol/m 2 /s) as previous described before transferring to dark condition [5]. ACC and β-estradiol treatments were conducted as described in previous studies [1, 4]. Hypocotyl lengths were surveyed from the intersection of cotyledon to root by ImageJ software and more than 20 seedlings were measured for each set of experiments.