Abstract: Quorum sensing is a term to describe bacterial communications, coordination of population behaviors and regulation of gene expressions depending on population density. Marine luminous bacterium Vibrio fischeri utilizes this mechanism to synthesize signal molecules N-Acyl homoserine lactones（AHLs）which serve as co-inducers with a transcriptional activator protein（LuxR）to regulate the expression of a set of target genes in an extremely high level. Based on the hypothesis that chloroplasts of higher plants were derived from cyanobacteria in ancient times and that the transcriptional and translational mechanisms of chloroplasts are highly similar to that of prokaryotes, we constructed that chloroplast transformation vector of the reporter gene GFP under the control of LuxR-dependent activation of the lux operon. The construct was then transformed into Escherichia coli. When no signal molecule of AHLs was added to the colonies, no GFP expression was detected. However, when AHLs were added, GFP expression was strong enough to be detected by naked eyes under ultraviolet lamp, demonstrating that the combination of the GFP gene and the lux operon is an ideal chemical inducible gene expression system which can then be used for studies of gene function in Escherichia coli.

Key words: Quorum sensing, LuxR gene, AHLs, Chemical inducible gene expression, Chloroplast transformation vector