The University of Cambridge-Génoplante collaboration to generate enhancer trap lines expressing gal4 and gfp in specific cell types

In the framework of a BBSRC, UK and Génoplante, France -funded collaboration between the University of Cambridge and Cirad we have generated a set of 13,000 enhancer trap rice lines expressing gal4 and gfp in specific cells or tissues as part of the insertion library, as mentioned above. The GAL4:GFP enhancer trapping system is based on the random insertion of a gene encoding a transcriptional activator from yeast, gal4, into the genome often close to an endogenous enhancer element (Figure 6). In the same construct, the upstream activation sequence (UAS) for GAL4 is placed upstream of gfp, thus activating expression of gfp when gal4 is activated. In many transformants, the expression of gal4, and thus gfp, occurs in discrete cell types, often defined in both a spatial and temporal manner.

This approach, first developed in Drosophila (Brand and Perrimon 1993, reviewed in Duffy, 2002) has proved powerful in Arabidopsis(see MRC Laboratory of Molecular Biology and http://enhancertraps.bio.upenn.edu/ in allowing specific cell types to be marked, and because an exogenous transcription factor is being 'trapped', it has allowed the trans-activation and mis-expression of proteins on a cellular basis (Figure 6). Aside from gene discovery resulting from detection of GFP activity, this system will provide for the first time a powerful tool for the future targeted expression of transgenes in an important monocotyledonous crop Figure 7. A File Maker Pro database has been first constituted to gather both as pictorial and textual information, the collection of GFP patterns. These data  are now integrated in the Oryza Tag Line database.

(For more information see Johnson et al. 2005, Plant J, 41 779-789)