Updated project metadata. Among multiple factors, light plays a decisive role in the switch from heterotrophic to autotrophic growth. Under dark condition, the rapeseed hypocotyl extended quickly with an apical hook, yellow and folded cotyledon, and the glyoxysome assembling. Whereas under light, the hypocotyl extended slowly, the cotyledon unfolded and turned green. In this study, we performed proteome profiling analyses to show the differential molecular responses of Brassica napus cotyledons to light and dark and reveal metabolic adaptations in postgerminative seedling establishment. In both light and dark-grown conditions.