[35] Transient expression analysis in plants using firefly luciferase reporter gene

This chapter discusses the transient expression analysis in plants, using firefly luciferase reporter gene. Firefly luciferase has been widely used in many organisms to monitor gene expression. The luciferase cDNA has been successfully expressed in bacteria, yeast, dictyostelium, monocot and dicot plants, and mammalian tissue culture cells. Most applications are based on the assay of luciferase enzyme in cell extracts. It is also possible to analyze luciferase expression in vivo because the substrate luciferin will diffuse across biological membranes. This approach has allowed the identification of E. coli cultures expressing luciferase and direct video imaging of tobacco protoplasts. Transgenic tobacco plants have been constructed, in which luciferase expression has been localized and quantitated in individual organs and tissues. Thus, the firefly luciferase gene is a sensitive and versatile reporter gene. Because light is so readily detected and quantified, luciferase expression is at present among the most sensitive reporter gene activities. Additional improvements are possible, however, to increase the flexibility of luciferase assays.