Abstract
'Vital' reporters provide the opportunity to monitor gene expression in living cells. In tobacco chloroplasts, GFP has been used as an available reporter for tissue- or cell-specific gene expression. However, GFP is too stable to monitor the variance of gene expression in response to environmental signals. Here, we show that the firefly luciferase is a useful reporter for detecting fluctuations in chloroplast gene expression. We introduced the luciferase gene driven from the plastid psbA promoter and its 5'-UTR into tobacco plastid genome. The transplastomic plant accumulated the luciferase protein, up to 1-2% of total cellular proteins. Bioluminescence of the transformant was clearly detected by using a cooled CCD camera. We further demonstrate that the accumulation of luciferase protein was obviously regulated by light, likely reflecting light-dependent expression of psbA. It strongly suggests that the firefly luciferase should be the high potential reporter for chloroplast gene expression in higher plants.
