Bioluminescence spectra of click beetle luciferases in higher plant cells

Reporter genes are often used to monitor gene expression in various organisms. To investigate the use of a dual-color luciferase reporter assay (DCRA) for monitoring expression of multiple genes in higher plants, we characterized the bioluminescence and the spectra of click beetle luciferases in planta. The DCRA consists of click beetle green luciferase (CBG68luc) and click beetle red luciferase (CBRluc). The green and the red bioluminescence from CBG68luc and CBRluc, respectively, are suitable for nondestructive in vivo assays because luminescence signals can be monitored selectively using optical filters. Using transgenic plants and a transient expression system, we introduced and expressed CBG68luc and CBRluc reporter genes in plant cells and obtained luminescence spectra by spectrometry. The spectral patterns from the transgenic plant cells were similar to those from E. coli transformed with the same reporter genes. Although plant tissues contain pigments and autofluorescent materials, our data suggest that the presence of these do not interfere with gene expression monitoring by DCRA, which is therefore applicable to monitoring the regulation of gene expression in plants.