Light-induced expression of the chimeric chalcone synthase-NPTII gene in tobacco cells

Abstract

A chimeric gene was constructed containing the light-inducible chalcone synthase (chs) promoter from Antirrhinum majus, the neomycin phosphotransferase structural sequence from Tn5 as a reporter gene (NPTII) and the termination region from chs gene 1 from Petroselinum hortense. This gene was introduced into tobacco plants with the help of Ti plasmid-derived plant vectors and NPTII expression was measured. Analysis of the chs promoter sequence indicated the position of several possible regulatory regions. These were deleted to test their influence on the expression of the chs-NPTII gene. The different chimeric genes were all shown to be active after transfer to tobacco with the exception of one, in which the entire 5' upstream sequence from -1200 to -39 was deleted. The transcription of a chimeric gene with a 1.2-kbp 5' upstream promoter sequence was shown to be light inducible in tobacco plants. The analysis of various deletions of this 5' upstream sequence indicates that a number of sequence motifs have a quantitative effect on gene expression. One of these sequence motifs (-564 to -661) contains a direct repeat of 47 bp and the sequence GTGGTTAG which corresponds to the consensus core sequences observed in animal gene enhancer sequences. Deletion of a fragment containing this direct repeat resulted in a reduction of NPTII expression by a factor of 5.