STO is regulated by environmental factors and phytohormones.

(A) The diurnal expression pattern of STO under both LD (16 h light/8 h dark) and SD (8 h light/16 h dark) conditions in eight-day-old seedlings. (B) The diurnal expression pattern of STO in eight-day-old seedlings of Col, sto-1 and STO-OE in LD. (C) The effect of vernalization on STO expression. Seedlings were either warm-treated (22°C, 2 d, in SD), cold-treated (4°C, 4 weeks, in SD) or cold-treated (4°C, 4 weeks, in SD) and then warm-treated (22°C, 2 d, in SD). (D) The effect of BR on STO expression. Seedlings were treated with BL (100 nM) for either 3 h or 4 d. All experiments were performed with two (A–B) or three (C–D) independent replicates, UBQ10 used as a control. White and black bars represent the light and dark periods, respectively. * means p