Functions of ETR1 HK activity for plant growth promotion under light. A, Phenotypes of the wild-type, etr1-7, and transgenic etr1-7 plants grown in the cycle of 16-h light and 8-h dark with light intensity of 75 μE m−2 s−1 (top) or 250 μE m−2 s−1 (bottom) for 21 d. B, Quantitative analysis (rosette diameter) of plant growth phenotypes under normal (75) and high (250) light intensity conditions. Values are means with sd, n = 20.