Abstract:Gene trap is a system that allows gene activity to be monitored by creating gene fusions with a reporter gene. Gene traps provide a powerful tool for isolating genes and determining gene functions. Reporter genes can be used to construct three basic types of gene traps: enhancer trap, promoter trap and gene trap. In an enhancer trap, the reporter gene is fused to a minimal promoter that is unable to drive reporter gene expression alone but can be activated by neighboring enhancer elements. Promoter traps and gene traps contain a promoterless report gene, so that reporter gene expression can occur only when the reporter gene inserts within a transcribed chromosomal gene, creating a transcriptional fusion. In this review, we describe how gene traps were developed, how to construct gene trap system, how gene traps were adopted to isolate genes and determine gene functions, what is the present status about applications of gene traps on plant molecular biology and why gene traps are likely to play an increasing important role in the future.