Experiments with gene-trap vectors containing the firefly luciferase (LUC) reporter genes were carried out with the aim of analyzing functions of the Arabidopsis genome. Studies with protein fusion-type trap vectors as well as an internal ribosome entry site (IRES)-assisted non-fusion-type vector revealed that both types of vectors were suitable for gene trapping in Arabidopsis, although there were some differences in trapping efficiencies. The established trap lines were subjected to analyses for light responses, demonstrating the powerful and unique applications of a LUC-trapping system. A systematic survey of the insertion sites of the T-DNAs in LUC-expressing lines revealed 12-41% gene-trapping efficiencies depending on the vector. We demonstrate that the LUC-trapping system provides a unique system with which to monitor temporal expression of plant genes.