With the full sequence of the rice genome becoming progressively available to the international scientific community, assigning a function for each gene is clearly the next challenge. Production of a large number of knock out lines by insertion mutagenesis is one tool to be developed to achieve this task. Several insertion elements such as Ac/Ds, Tos 17 or T-DNA have recently been evaluated for rice functional genomic studies (ref. 1 to 4). Our project is to generate a large number of T-DNA insertion lines of rice cv. Nipponbare by the end of 2003. Our strategy is to identify all the flanking sequences of each T-DNA line (FST) to allow in silico reverse genetic analysis. At first, the T-DNA carry a gusA gene enhancer trap system to follow in vivo gene expression by GUS assay. This poster will summarize the status of the work. Histochemical assays conducted on vegetative and reproductive organs of more than 2,000 enhancer trap fines allowed detection of GUS-specific activity in different organs. First analysis on 2500 FSTs indicate that the average size of the FST is 245 bp in length. Using blast N search, we have found that the distribution of the assigned FST along the different chromosomes is well correlated to the amount of sequences available for each chromosome. These primary results indicate that T-DNA insertions are randomly distributed along the rice genome. As an example, we will present a map of the T-DNA insertion on the nearly completed sequence of the rice chromosome 1. All the data will be inserted in the future in a public database OryzaTagLine.