BBX31 up-regulates HY5 transcript levels under UV-B light in a UVR8-dependent manner. A and B, Relative transcript levels of HY5 in 35S:BBX31#1 and bbx31-1 lines in WL (long day, 16 h/8 h; A) and after 1 h of UV-B irradiation (1.4 W m−2) treatment (B). C, Relative transcript levels of HY5 in uvr8-6 and uvr8-6/35S:BBX31 lines in WL (long day, 16 h/8 h) and after 1 h of UV-B irradiation (1.4 W m−2) treatment. Asterisks indicate statistically significant differences (***, P < 0.001) as determined by Student’s t test; ns, nonsignificant. Error bars represent sd of at least two replicates.